About the Watts per Kg Calculator
Power-to-weight ratio — watts per kilogram (W/kg) — is the single best predictor of how fast a cyclist climbs. This watts per kg calculator divides your power, usually your functional threshold power (FTP), by your body weight in kilograms and places the result on an approximate ability scale from untrained to world class.
It is built for road cyclists, triathletes and indoor riders on Zwift or similar apps who want to compare themselves fairly with heavier or lighter riders, set a realistic FTP goal, or see whether gaining power or losing weight moves them up faster. You can enter weight in kilograms or pounds.
There is no official W/kg classification. The rider levels here are simplified, rounded bands in the spirit of the Coggan power profile for FTP (from Allen and Coggan’s Training and Racing with a Power Meter), with female thresholds about 15% lower. They are not Coggan’s exact table: here “World class” starts at 6.0 W/kg for men, whereas Coggan’s published range extends higher, to about 6.4 W/kg for the very best riders. Treat the level as a guide, not a race category: real categories depend on race results, and W/kg matters less on flat roads, where absolute watts and aerodynamics dominate.
With the default inputs, the power-to-weight is 3.33 W/kg. Change any value above to recalculate instantly.
How to use the watts per kg calculator
- 1Enter your FTP (or the average power of an effort you want to compare).
- 2Enter your body weight and choose kg or lb.
- 3Select sex to use the matching level bands.
- 4Optionally add bike and kit weight for a climbing (system) ratio.
- 5Check the watts or kilos needed to reach the next level.
Formula and method
Power-to-weight ratio is your power in watts divided by your body mass in kilograms; pounds are converted with 1 lb = 0.45359237 kg. The watts needed for the next level are the next threshold × your weight minus your current power, and the weight-loss alternative is your weight minus power ÷ next threshold.
The optional system W/kg adds bike and kit to the denominator, which is what actually has to be lifted up a climb. Level bands are simplified, rounded FTP benchmarks (not Coggan’s exact table): male lower bounds at 2.5, 3.2, 3.7, 4.2, 4.8, 5.4 and 6.0 W/kg; female lower bounds at 2.1, 2.7, 3.1, 3.6, 4.1, 4.6 and 5.2 W/kg (roughly 15% lower). At the top band there is no next level, so the “to next level” figures are hidden. System W/kg is shown only when you enter a bike and kit weight.
- W
- Sustained power in watts, usually FTP
- kg
- Rider body mass in kilograms
Worked examples
250 W FTP at 75 kg
250 ÷ 75 = 3.33 W/kg, a fit amateur level. Reaching 3.7 W/kg would take 3.7 × 75 = 277.5 W (27.5 W more), or weighing 250 ÷ 3.7 = 67.6 kg (7.4 kg less).
200 W at 130 lb, female rider
130 lb is 58.97 kg, so 200 W is 3.39 W/kg — in the “Good” band for women. The next band at 3.6 W/kg needs 212.3 W, about 12 W more.
320 W at 68 kg with a 9 kg bike and kit
320 ÷ 68 = 4.71 W/kg, just under the 4.8 excellent threshold. Adding 9 kg of bike and kit gives 320 ÷ 77 = 4.16 W/kg of system power on a climb.
400 W at 62 kg — top band
400 ÷ 62 = 6.45 W/kg, above the 6.0 W/kg lower bound of the top band on this scale. There is no higher level, so the watts and weight-to-next figures are hidden.
Frequently asked questions
What is a good watts per kg for cycling?+
For FTP, around 2.5–3 W/kg is typical for regular recreational riders, 3.5–4 W/kg is strong amateur racing level, above 5 W/kg is elite or professional, and the best Grand Tour climbers hold roughly 6–6.4 W/kg at threshold.
Should I use FTP or 20-minute power for W/kg?+
Use FTP for comparisons with rider levels, since the bands are based on threshold power; FTP is often estimated as 95% of 20-minute power. Short efforts like 5-minute or 1-minute power give much higher W/kg and use different benchmarks.
Is it better to gain watts or lose weight?+
Both raise W/kg. For a rider with excess body fat, losing weight can be quicker, but for already-lean riders, gaining power is safer and also helps on flat roads where absolute watts matter more than weight.
Does bike weight matter for watts per kg?+
Standard W/kg uses body weight only. On a climb, however, you lift the bike, bottles and kit too, so the system W/kg (power ÷ rider + bike) is what really sets climbing speed.
Why do women have lower W/kg thresholds?+
On average women carry more essential body fat and less muscle mass relative to body weight, so elite female FTP values are roughly 10–15% lower than male values at the same relative level.
This tool gives general estimates and is not medical advice. Talk to a doctor or qualified professional about your health, diet or training.