Tennis String Tension Calculator (kg ↔ lbs)
The conversion uses the exact definition 1 lb = 0.45359237 kg (NIST Handbook 44, Appendix C).
Common conversions
| lbs | kg | lbs | kg |
|---|---|---|---|
| 40 | 18.1 | 52 | 23.6 |
| 44 | 20.0 | 54 | 24.5 |
| 46 | 20.9 | 55 | 24.9 |
| 48 | 21.8 | 56 | 25.4 |
| 50 | 22.7 | 58 | 26.3 |
| 51 | 23.1 | 60 | 27.2 |
More tools: tennis and padel calculators.
What tension changes do
- Lower tension: the string bed deflects more, giving more power, a larger effective sweet spot and more comfort, but less control.
- Higher tension: less deflection, so more control and a flatter trajectory, but less power and more shock.
- String type matters: stiff polyester feels firmer than multifilament at the same number. That’s why many players string poly lower. See our strings guide.
Frequently asked questions
How many kg is 50 lbs string tension?
22.68 kg (1 lb = 0.45359237 kg).
Should I string lower or higher?
Lower tension gives more power and comfort. Higher tension gives more control. Stay inside the range printed on your racket, and move in small steps so you can feel the difference.
Does padel have string tension?
No. Padel rackets have no strings. Core hardness (EVA or foam) and face material do the equivalent job. See our guide to EVA vs foam padel rackets.
Sources
- NIST Handbook 44 (2026), Appendix C — General Tables of Units of Measurement — 1 avoirdupois pound = 0.45359237 kg