Badminton String Tension kg to lb: A Conversion Guide

Last checked: August 2026 · Written by the Badminton House player-led team.

The fastest formula is kgf × 2.20462262185 ≈ lbf. For example, 12 kgf converts to 26.5 lbf to one decimal place. If the full result is rounded once to a whole pound, it becomes 26 lbf. Those are two ways of displaying the same conversion, not two tension recommendations.

This guide stays focused on unit labels, lookup values and rounding. For the distinction between a machine setting and other string-bed measurements, read what badminton string-tension numbers mean. If you are trying to choose a tension rather than convert an existing request, use our badminton string-tension guide and consult your stringer.

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What do kg, kgf and lbf mean in badminton stringing?

Kilograms measure mass, while kilogram-force and pound-force measure force. A stringing machine may display “kg” and “lbs” as compact labels, but the tension setting is understood as kgf or lbf. Writing the force labels on a job note removes ambiguity without changing the requested setting.

The distinction begins with the unit definitions. The International Bureau of Weights and Measures defines the kilogram, symbol kg, as the SI unit of mass. By contrast, the NIST force conversion table lists kilogram-force and pound-force as force units.

Under those standard definitions, 1 kgf equals exactly 9.80665 newtons and 1 lbf equals exactly 4.4482216152605 newtons. Their ratio gives approximately 2.20462262185 lbf per kgf. In the reverse direction, 1 lbf equals exactly 0.45359237 kgf.

The shorthand is visible on real stringing equipment. The Yonex Precision 8.0 specifications present the machine’s force-setting range using “lbs” and “kg.” That display convention does not make kg a force unit. It shows why players and stringers commonly encounter the shorter labels.

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What is the 8–15 kgf badminton string-tension conversion table?

Using the NIST force definitions, the table converts each integer setting from 8 through 15 kgf into lbf. The middle column rounds each full calculation to one decimal place; the last rounds each unrounded value directly to a whole pound. Neither column recommends a tension.

The 12 kgf row illustrates why the two rounded columns should be calculated separately. Its full conversion is approximately 26.45547 lbf. That becomes 26.5 to one decimal place, while rounding the full value directly to a whole pound gives 26. Under a half-up rule, rounding the displayed 26.5 again would produce 27, so calculate the whole-pound value directly from the unrounded 26.45547 result.

Read the table horizontally as a unit translation. Do not read higher rows as upgrades, lower rows as beginner settings or any part of the span as a universal safe range. Before using a converted value, defer to the tension marking for the exact racket and to the stringer assessing the job.

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How should you convert and round a stringing request?

Calculate with the full conversion factor, then round the result once to the increment the actual stringing machine can set. Record the original request beside the rounded conversion so the stringer can verify the unit translation and the final settable value.

The factors come from the exact force definitions documented in the NIST Guide to the SI footnotes. Keep all available digits during the calculation so the final rounded result reflects the original request rather than an already shortened intermediate number.

1. Confirm the starting unit. Establish that a request written as “kg” means kgf and that a pound request means lbf.
2. Use the full factor. Multiply kgf by approximately 2.20462262185, or multiply lbf by exactly 0.45359237.
3. Ask about the machine increment. The stringer should identify what the specific machine can set.
4. Round once. Round the full result directly to that increment and label the rounded number as lbf or kgf.

Machine increments are not universal. The Yonex Precision 8.0, for example, specifies 0.5 lb and 0.2 kg increments; another machine may use different increments. Confirm the settable increment with the stringer who will do the job.

The NIST conversion guidance supports retaining the conversion factor’s digits and rounding the final converted value. In practical terms, preserve the original request, show the calculated conversion and let the stringer confirm the final machine setting.

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How should you give the converted tension to a stringer?

Give the stringer the original value, its precise force unit and the converted result. Then confirm the exact racket’s marked advice and the machine increment. If an existing request lists mains and crosses separately, convert each value separately without inventing or recommending a difference between them.

• Keep the original: write “12 kgf requested” rather than replacing it with an unexplained pound number.
• Add the conversion: write “approximately 26.45547 lbf; 26.5 lbf to one decimal.”
• Label any rounding: identify whether the shown result is rounded to one decimal, a whole pound or the machine’s confirmed increment.
• Preserve separate instructions: when a job already provides different main and cross values, apply the same formula to each one independently.
• Check the racket and stringer: never use a converted table value to exceed the exact racket’s marking or the stringer’s stated limit.

There is no single racket range hidden inside the conversion. Yonex currently lists 20–28 lb for the Nanoflare 1000 Game and 16–20 lb for the B7000MDM. These model-specific examples differ, which is why the table cannot define a universal tension range. Neither example recommends a setting for a different racket.

If you already have a requested force, this guide gives you the clean conversion. If you still need to decide on the underlying setting, return to the racket marking, speak with your stringer and use the full string-tension guide for the separate selection question.