Polyester / co-poly
44–54 lbs20–24.5 kg
The stiffest common construction. Start below an equivalent nylon or gut reference and prioritize comfort if you are new to poly.
Frame-range-first tool
Tennis String Tension Calculator
Enter the range printed on your racquet, choose your string construction and playing goal, and get a sensible starting range to test. Already have a setup? Use Fine-Tune mode to plan one small change for your next string job.
Frame-range firstLbs and kgRuns in your browser
Direct answer
There is no single correct tennis string tension, so this calculator produces a starting range rather than one number. It starts with the broad range for your string construction, selects a lower, balanced, or upper goal window within that range, then intersects that window with your racquet manufacturer’s recommended range. The midpoint of that final overlap gives you a neutral first test. The output is a reference tension for your next string job, not a prediction of what the finished stringbed will measure afterward. After stringing, save a fresh-string baseline and follow how that racquet changes from its own starting point.
Frame range first
Find your starting test range
Pick a mode, enter the tension range your racquet lists, and the calculator returns a starting test range inside that range. It gives you a reference tension to request from your stringer — not a measurement of an installed stringbed.
Start a New Setup
Fine-Tune My Current Setup
Runs entirely in your browser. Nothing you enter is sent to a server.
Guidance data last reviewed ·Download the guidance JSON
Nothing hidden
How the tennis string tension calculator works
Every step is arithmetic you could do on paper. There is no proprietary score, no invented base tension, and no unexplained adjustment for your frame, your level, or the weather.
- You enter your racquet’s printed range
The frame manufacturer’s recommended tension range, in lbs or kg. This is the calculator’s primary frame-specific guardrail, and the tool treats it as a hard boundary.
- You choose your string construction
Polyester, hybrid, synthetic gut, multifilament, or natural gut. Construction determines the broad starting range.
- You choose one playing goal
More comfort and easier depth, a balanced starting point, or a firmer response with more control. One goal at a time keeps the result testable.
- The tool looks up the construction range
It reads the construction’s starting range from the site’s public tension dataset, then selects the lower, middle, or upper goal window inside it. Those goal windows are String Tension AI’s own division of the construction range.
- It intersects that window with your frame range
Only tensions inside both the goal window and your racquet’s printed range survive. If nothing survives, the tool says so instead of inventing a number.
- It shows the range, the midpoint, and the working
You see the overlap in lbs and kg, a neutral first test at the midpoint, and a breakdown of every value that produced it.
Want the underlying tables instead of a calculated answer? Browse the complete tennis string tension chart, or browse every guide and tool.
The frame-specific guardrail
Start with your racquet’s recommended range
The frame manufacturer’s recommended range is the calculator’s primary frame-specific guardrail. It is printed on most racquets, usually inside the throat or on the hoop, and it is also published on the manufacturer’s specification page. It is the one range in this process that comes from the company that engineered the frame you are actually holding. String manufacturers can also publish product-specific instructions, so follow those too where they apply. If your racquet’s print has worn off, our racquet tension-range lookup lists manufacturer-published ranges for current frames, each with its source.
That is why this calculator asks for it first and treats that recommended range as a hard boundary. Published construction guidance describes strings in general; your printed range describes your racquet. When the two disagree, the frame wins. If a goal window sits entirely outside your printed range, the tool reports that there is no overlap rather than nudging you past the limit — which is exactly the case where a general-purpose recommendation would be least trustworthy.
If you cannot find the range, get it before you string rather than guessing. Check the frame, the manufacturer’s product page, or ask your stringer. The calculator will not invent a frame limit for you.
If you have not chosen a string construction yet, or want a restring window and a monthly cost alongside the range, the tennis string setup finder applies the same frame-first logic to five questions and suggests a construction to try.
The biggest single input
How string construction changes the starting point
Wilson publishes different first-time-strung ranges for different string materials, and the gap between the stiffest and the most elastic construction is six pounds at both ends. The ITF describes the same ordering in physical terms: synthetic constructions do not have natural gut’s low dynamic stiffness, and polyester and kevlar are used to increase durability.
Hybrid
46–56 lbs20.9–25.4 kg
Use the frame range as the guardrail. For polyester + nylon hybrids, Wilson recommends stringing the polyester component about 2 lbs (1 kg) lower than the nylon component. Follow product-specific guidance for other hybrid combinations.
Synthetic gut / nylon
50–60 lbs22.7–27.2 kg
A practical reference construction with moderate comfort, power, and durability.
Multifilament
50–60 lbs22.7–27.2 kg
A softer, elastic construction suited to players who prioritize comfort and accessible power.
Natural gut
50–60 lbs22.7–27.2 kg
The most elastic construction here and the strongest tension holder, but it needs protection from moisture and abrasion.
Base ranges adapted from Wilson Sporting Goods (accessed September 5, 2026). Wilson publishes a combined nylon/gut band of 50–60 lbs; String Tension AI applies that band to synthetic gut, multifilament, and natural gut. Kilograms are converted from pounds here rather than copied, so they may differ slightly from Wilson’s rounded figures.
For how each construction is built and why it holds tension differently, read tennis string types explained.
At a glance
“What tension should I use?” quick reference
If you only want the broad band for your string type, this is it. Use it where it overlaps the range printed on your racquet, and treat it as construction-level starting guidance rather than a recommendation for your specific frame.
| Construction | Broad construction guidance | What to know |
|---|---|---|
| Polyester / co-poly | 44–54 lbs20–24.5 kg | The stiffest common construction. Start below an equivalent nylon or gut reference and prioritize comfort if you are new to poly. |
| Hybrid | 46–56 lbs20.9–25.4 kg | Use the frame range as the guardrail. For polyester + nylon hybrids, Wilson recommends stringing the polyester component about 2 lbs (1 kg) lower than the nylon component. Follow product-specific guidance for other hybrid combinations. |
| Synthetic gut / nylon | 50–60 lbs22.7–27.2 kg | A practical reference construction with moderate comfort, power, and durability. |
| Multifilament | 50–60 lbs22.7–27.2 kg | A softer, elastic construction suited to players who prioritize comfort and accessible power. |
| Natural gut | 50–60 lbs22.7–27.2 kg | The most elastic construction here and the strongest tension holder, but it needs protection from moisture and abrasion. |
Using two different strings? Read the hybrid mains, crosses, and split-tension guide before choosing the two reference settings.
Direction, with honest magnitudes
Lower vs higher tension: what actually changes?
Wilson states the general rule plainly: the higher your string tension, the more control you have; the looser your tension, the more power you get. The useful detail is in how large those effects are and what they do not cover.
More power and a softer impact
- The ITF explains the mechanism: looser strings deform the ball less, so less energy is lost and exit ball velocity increases.
- The measured size is modest. The ITF reports that a 25 percent decrease in tension corresponds to about a 2 percent increase in groundstroke speed, and roughly 1 percent on a serve.
- Comfort has a mechanism too: increased dwell time spreads a smaller force over a longer period, which the ITF links to reduced shock on impact.
- Babolat associates a lower tension, and a thinner gauge, with more comfort and more power.
A firmer, more predictable launch
- The ITF gives three reasons a less stiff stringbed hurts control: the hitting surface distorts more and widens the range of exit angles, the ball deforms less so the directing contact area shrinks, and longer dwell time lets the racquet rotate further during impact.
- Wilson’s control halves are the upper half of each published band: 50–54 lbs for polyester, 52–56 lbs for hybrids, and 56–60 lbs for nylon or gut.
- Control is a measured response, not the highest safe number. Going too high can reduce comfort and easy depth.
- Spin is not on this list. The ITF reports no appreciable spin difference between low- and high-tension strings.
For the longer version of each side, read best tennis string tension for control and best tennis string tension for spin. The spin guide is the one to read before you treat any tension number as a spin lever. If comfort is your reason for going lower, string tension for arm comfort compares tension with material, gauge and frame stiffness, and labels the evidence behind each.
Precision you can defend
Why this calculator gives you a range, not one “perfect” number
A single number would be easier to read and harder to justify. There is no perfect tension, and nothing in the published evidence supports pretending otherwise.
Wilson publishes bands at every tier — the base ranges, and the power and control halves inside them. The ITF shows why a band is the honest unit: the same reference tension produces a different stringbed in a different frame, because enlarging the head lowers stringbed stiffness and widening the spacing between strings makes the face more flexible. The measured effects are also small relative to the confidence a single number implies. Wilson itself closes its guidance by acknowledging that choosing string tension is a complicated process and suggesting you ask your coach.
So the useful output is a window you can act on: a range narrow enough to be a real experiment, a midpoint to try first, and a next step if the first try is not right. Any tool that returns one optimal-sounding figure, or a 0-to-100 performance score, is asserting a precision that no source in this set supports.
No hidden coefficient
Should beginners and advanced players use different tension?
This calculator applies no skill adjustment, and the reason is in the published data itself. Wilson does publish sub-bands by playing level, and their direction reverses between constructions. For nylon, gut, and hybrids, Wilson’s level bands move down as skill goes up. For polyester, they move up. Any single rule such as “beginners string lower” would contradict Wilson for three of the five constructions here, and the opposite rule would contradict Wilson for polyester.
What level does change, in both Wilson’s and Babolat’s guidance, is the string. Wilson suggests nylon strings for beginners, hybrids as intermediate players progress, and a full polyester bed for advanced players. Babolat likewise ties level to string family and gives no tension numbers by level at all. Wilson also frames the underlying variable as swing speed rather than a label: players with slower racquet-head speeds want the strings to add power, while faster swings want the strings to supply control.
Practically: choose your construction with your level in mind, then use the frame range and the construction window to pick the number. Beginners in particular should not chase the highest number. A comfortable nylon or multifilament setup near the middle of the racquet’s printed range is usually a more useful benchmark. Build repeatable technique first, then adjust one variable at a time with a qualified stringer.
Context, not arithmetic
What about head size, pattern and gauge?
All three genuinely change how a stringbed behaves. None of them has a published pound adjustment in the sources this page uses, so the calculator offers them as context fields and states plainly that they do not change the math.
The ITF describes the mechanism in one passage: the stiffness of the stringbed is affected by the arrangement of the strings, so increasing the space between strings makes the face more flexible, and increasing string length by enlarging the head also lowers stringbed stiffness. On gauge, the ITF adds that a thinner gauge makes the string more flexible but less durable, and notes that the belief that thinner strings impart more spin has little empirical support. Babolat’s practical version points the same way: a thinner gauge or lower tension helps comfort and power, a thicker gauge or higher tension helps control and durability.
The correct conclusion is the opposite of a head-size coefficient. Because the same reference tension does not produce the same stringbed in a different frame, the honest response is to anchor on the range that frame’s maker prints, output a window rather than a point, and then measure the finished racquet. Competitor calculators that add or subtract pounds for head size are asserting a rule no primary source in this set quantifies.
The longer explanations are in the tennis string gauge guide and in string pattern and tension, which covers open and dense patterns and head size.
One variable at a time
How to fine-tune your next string job
Fine-Tune mode assumes you already have a reference tension and one thing you want to change. The point is to run an experiment you can actually learn from, which means moving in small steps and holding everything else still.
Starting from scratch
- Read your frame’s printed range.
Find it on the racquet or the manufacturer’s specification page before anything else.
- Pick the construction you will actually buy.
Construction determines the broad starting range.
- Choose one goal.
Comfort and depth, balanced, or a firmer response. Not all three.
- String at the midpoint of the overlap.
Request that number as the reference tension and write it down.
- Measure a fresh-string baseline.
Anchor the racquet’s history to its own starting point.
- Record your first-session response, then confirm it.
Repeat over another comparable session or two. Avoid judging from only a handful of hits, but do not ignore a clear comfort or control problem.
Adjusting a setup you already have
- Rule out dead strings first.
An old stringbed will hide whatever the tension change does.
- Name one symptom.
Launching too high, too firm to get depth, or a comfort problem.
- Move about 2 lb (≈0.9 kg).
Keep the same string and gauge, and stay inside the frame range.
- Compare against your baseline.
Measure the new job fresh, then judge the change over several sessions.
Move by about 2 lb (≈0.9 kg) rather than making a large jump. Large jumps make it harder to learn what actually improved, and they burn a whole string job’s worth of playing time on an ambiguous result. The 2 lb step is String Tension AI’s practical heuristic, not a number published by Wilson, Babolat, or the ITF.
Don’t tune around dead strings.
If the current stringbed is already outside its useful window, its age can confound a tension experiment. A worn setup may lose snapback, change feel, or become less predictable depending on the string construction, and it drifts away from whatever number you requested — so a 2 lb change can get credited or blamed for something the strings were doing already. Check dead tennis string symptoms first, use when to restring your tennis racquet to decide whether the current job is finished, and compare your hours against tennis string lifespan by hours. Restring the same setup, then run the experiment from a fresh baseline.
Illustrative only
Worked examples
These four examples are illustrative walkthroughs of the calculator’s arithmetic, not recommendations for your racquet. Substitute your own printed range and construction.
1. A first polyester string job
- Frame range
- 45–55 lbs (20.4–24.9 kg)
- Construction
- Polyester / co-poly, published 44–54 lbs
- Goal
- Balanced starting point
- Goal window
- 47–51 lbs
- Overlap with the frame
- 47–51 lbs (21.3–23.1 kg)
- First test
- 49 lbs (22.2 kg)
The balanced polyester window sits entirely inside this frame’s printed range, so the overlap is the goal window itself and the first test is its midpoint. This is the ordinary case: published construction range, goal window inside it, then the frame range as the boundary.
2. What happens when the ranges barely overlap?
- Frame range
- 50–60 lbs (22.7–27.2 kg)
- Construction
- Polyester / co-poly, published 44–54 lbs
- Goal
- Balanced starting point
- Goal window
- 47–51 lbs
- Overlap with the frame
- 50–51 lbs (22.7–23.1 kg)
- First test
- 50.5 lbs (22.9 kg)
The balanced polyester window sits mostly below this frame’s minimum, so the overlap is narrow and the first test lands at the bottom of the printed range. That is the guardrail working, not a fault in the result.
3. 52 lbs feels too firm
- Current reference tension
- 52 lbs (23.6 kg)
- Symptom
- Hard to get depth, response feels too firm
- Next experiment
- 50 lbs (22.7 kg)
- What stays the same
- Same string, same gauge, same stringer
One 2 lb (≈0.9 kg) step down, inside the frame range, with nothing else changed. If depth improves but the launch gets too high, the answer is somewhere between the two numbers rather than further down.
4. The strings already feel dead
- Symptom
- Inconsistent response, no snapback, unpredictable depth
- Next experiment
- None yet
- Do this instead
- Restring the same setup at the same reference tension
- Then
- Measure a fresh baseline and play a few sessions before changing anything
Changing tension on top of a worn stringbed produces an uninterpretable result. Re-establish the known setup first, then make one deliberate change from there.
Close the loop
After stringing, measure the result
The number this calculator gives you is a reference tension: the pull setting you request from your stringer for the next string job. What an acoustic app reports later is a different quantity — a modeled current-tension estimate for the installed stringbed at the moment you measure it. The machine setting and a later modeled current-tension estimate are not interchangeable, and several installation, setup, timing, and measurement variables sit between them. There is no responsible rule such as “reference tension minus X percent equals app tension” for every setup, and this page does not predict what your app will read.
What you can do is give the racquet its own starting point. Measure the finished string job while it is fresh, save that reading as the baseline for this racquet and setup, and take later readings with the same routine. A baseline changes the question from “Does my phone reproduce the number on the machine?” to “How has this racquet changed from its own fresh, repeatable starting point?” That is also the only way to find out whether the tension change you just tested actually held up over several sessions.
For the step-by-step routine, use how to measure tennis string tension. To compare a current reading with your baseline and your personal floor, use the racquet string tension checker. For how strings change between jobs, read tennis string tension loss, and for what a phone reading can and cannot support, read tennis string tension app accuracy.
Clear answers
Tennis string tension calculator FAQ
What tension should I string my racquet at?
Start from the tension range printed on your frame — that is the manufacturer’s guardrail. Then choose your string construction and your playing goal: the calculator selects a goal window inside the broader published construction range and intersects that window with your frame range. Wilson’s first-time-strung guidance is 50–60 lbs for nylon or gut, 46–56 lbs for a hybrid, and 44–54 lbs for polyester. Treat the result as a starting test range, not a prescription.
What is a good starting tension?
A defensible starting point is the midpoint of the overlap between your frame’s recommended range and the selected goal window within the broader construction range. Wilson calls 50–60 lbs for elastic materials its base recommended tension, and describes the wider choice as complicated enough to be worth discussing with a coach. Test that midpoint first, then change one variable at a time.
What tension should I use for polyester strings?
Wilson publishes 44–54 lbs (20–24.5 kg) for polyester, with 50–54 lbs as the control-oriented half. Wilson’s stated reason for stringing polyester looser is that it is a stiffer material. The ITF likewise groups polyester with the stiffer, durability-oriented constructions. Stay inside your frame’s printed range, and treat comfort as a reason to test lower rather than a promise.
Should polyester be strung lower than nylon?
Yes, according to Wilson: “Because polyester is a stiffer material, string 2lbs (1kg) looser than nylon,” with the example of polyester at 51 lbs and nylon at 53 lbs. The published base ranges differ by six pounds at both ends — 44–54 lbs for polyester against 50–60 lbs for nylon or gut. Your frame’s printed range still wins.
What tension gives more control?
Wilson states that higher tension gives more control and lower tension gives more power. The ITF explains the mechanism: a less stiff stringbed distorts more at impact, widens the range of exit angles, shrinks the contact area, and extends dwell time. Wilson’s control halves are 50–54 lbs for polyester, 52–56 for hybrids, and 56–60 for nylon or gut.
What tension gives more power?
Lower tension, within limits. Wilson says looser strings give more power, and the ITF explains that looser strings deform the ball less, so less energy is lost. The ITF also sizes the effect honestly: a 25 percent decrease in tension corresponds to about a 2 percent increase in groundstroke speed and roughly 1 percent on a serve.
Does lower tension give more spin?
Not reliably. The ITF reports “no appreciable difference in spin produced by rough or smooth, low- or high-tension strings.” Tennis Warehouse University’s own lab testing found the opposite direction, but from a 30 lb versus 60 lb contrast in a non-standard pattern. Spin depends far more on swing path, racquet-head speed, string shape, snapback, and string condition.
How much should I change tension by?
Move about 2 lb (≈0.9 kg) at a time, keep the same string and gauge, and write down what changed. Large jumps make it harder to learn what actually improved. Keep every step inside the range printed on your frame. The 2 lb step is String Tension AI’s own practical heuristic, not a number published by Wilson, Babolat, or the ITF.
Should beginners string lower than advanced players?
There is no clean rule, so the calculator applies no skill coefficient. Wilson’s own level sub-bands move down with skill for nylon, gut, and hybrids but up with skill for polyester, so any single adjustment would contradict Wilson somewhere. Wilson ties level to string choice instead. Beginners are usually better served by a comfortable setup near the middle of the frame’s printed range.
Does head size change string tension?
It changes the stringbed, not the number you should request. The ITF states that “increasing the length of the strings, by enlarging the head for example, lowers the stiffness of the stringbed,” so the same reference tension feels softer in a larger head. No source in our set quantifies a pound adjustment, so the calculator does not apply one.
Does string pattern change string tension?
It changes stringbed behavior rather than the recommended number. The ITF notes that increasing the space between strings makes the face more flexible. Tennis Warehouse University’s own testing found more string movement and more measured spin in more open patterns. Neither supports a specific pound modifier, so pattern is offered as context in the calculator and not as arithmetic.
Does string gauge change tension?
Gauge changes feel and durability rather than the published tension window. The ITF states that a thinner gauge makes the string more flexible but less durable, and that the belief thinner strings add spin has little empirical support. Babolat associates thinner gauge with comfort and thicker gauge with control and durability. Keep gauge constant while you test a tension change.
Should mains and crosses use the same tension?
Not necessarily. The only published delta in our sources is Wilson’s material rule: string the polyester component about 2 lbs (1 kg) looser than the nylon component, with an example of polyester at 51 lbs and nylon at 53 lbs. The difference follows the string, not the position. Confirm the split with your string maker and your stringer.
How do I choose tension for a hybrid?
Wilson publishes 46–56 lbs for hybrids, with 46–51 as the power half and 52–56 as the control half, then applies the 2 lb (1 kg) rule to the polyester component. Use your frame’s printed range as the guardrail, record both reference tensions separately, and change only one side at a time when you test.
Is this number the same as what a tension app measures?
No. This calculator outputs a reference tension — a stringing-machine pull setting for your next string job. A tension app produces a modeled current-tension estimate for the installed stringbed at a later moment. The two are not interchangeable, and there is no responsible rule such as “reference tension minus X percent equals app tension” for every setup.
Why does the calculator give a range instead of one number?
Because the published evidence is expressed as ranges. Wilson publishes bands, not points, at every tier. The ITF shows that the same reference tension produces a different stringbed in a different head size or pattern, and that the measured effects are small — about 2 percent more groundstroke speed for 25 percent less tension. A range is a test window you can act on.
What if I do not know my racquet’s tension range?
Find it before you string. It is normally printed inside the throat or hoop, and otherwise available from the manufacturer’s product page or your stringer. The calculator will not invent a frame limit for you. Without it you can still use the published construction range on its own, but you lose the one guardrail the frame maker actually stands behind.
Evidence and method
Sources and calculation methodology
Different parts of this page rest on different kinds of evidence. Manufacturer guidance supplies the published ranges. A governing-body technical document supplies the physics. Retailer-operated lab testing is identified as such. The windows inside each published range are this site’s own methodology, and are labelled that way wherever they appear.
- Wilson Sporting Goods publishes the first-time-strung base ranges used here: 50–60 lbs for nylon or gut, 46–56 lbs for hybrids, and 44–54 lbs for polyester. String Tension AI applies the nylon/gut band to synthetic gut, multifilament, and natural gut.
- Wilson also publishes a two-way power and control split inside each band. The control halves this page quotes — 50–54 lbs for polyester, 52–56 lbs for hybrids, and 56–60 lbs for nylon or gut — are Wilson’s own upper halves.
- Wilson’s stated rule for hybrids is to string a polyester component about 2 lbs (1 kg) looser than nylon.
- The International Tennis Federation’s strings overview supplies the stringbed-stiffness mechanisms for control, power, comfort, head size, string spacing, and gauge, plus the magnitude of the tension-to-speed effect and the finding of no appreciable tension effect on spin.
- Babolat supplies the practical direction for comfort, power, control, gauge, and restring cadence. It is cited here for those directions only. Babolat also associates a thicker gauge or a higher tension with more spin; that specific claim runs opposite to the ITF’s finding, so this page does not rely on Babolat for spin.
- Tennis Warehouse University’s own testing reports a positive tension-to-spin relationship from a 30 lb versus 60 lb contrast in a non-standard pattern. It is a retailer-operated lab, its result runs opposite to the ITF’s, and its comparison is far wider than any real starting range, so this page does not use it to recommend tension for spin.
- The three goal windows are three equal 4 lb windows spanning each published 10 lb construction range, starting at the base minimum and stepping up 3 lbs at a time, so neighbouring windows overlap by 1 lb. The upper window is the top 4 lbs of the band, which is exactly Wilson’s published control half.
- The lower and middle windows are String Tension AI’s own. The lower window is deliberately not Wilson’s power half: Wilson’s power half is the bottom 5 lbs of each band, so our lower window ends 1 lb below it. That is a consequence of using equal-width windows, not a disagreement with Wilson.
- The result is the arithmetic intersection of that window with the frame range you enter. Nothing is added or subtracted for level, head size, string pattern, or gauge.
- Kilograms are converted from pounds at 0.45359237 and rounded to one decimal place rather than copied from any source’s own rounding.
- The 2 lb (≈0.9 kg) adjustment step is a practical heuristic published by this site, not by Wilson, Babolat, or the ITF. Wilson’s own rounded wording for its hybrid rule is 2 lbs (1 kg).
- The calculator does not use a machine-learning model or a hidden AI score, and it runs entirely in your browser.
- Wilson Sporting Goods — What String Tension Should I Use in My Tennis Racket? · accessed 2026-09-05
- Babolat — How to choose your tennis string · accessed 2026-09-05
- International Tennis Federation — Rackets and Strings — Strings · accessed 2026-09-05
- Tennis Warehouse University — Spin and String Stiffness in Tennis · retailer-operated lab testing · accessed 2026-09-05
- Tennis Warehouse University — String Patterns and Spin · retailer-operated lab testing · accessed 2026-09-05
Wilson and Babolat guidance was re-verified September 5, 2026. The ITF document and both Tennis Warehouse University pages were re-checked the same day. Read more about our research and correction standards.
Stop guessing after the first string job
Save your racquet, string setup, tension history, and playing hours in String Tension AI.
Download String Tension AI Free