Cycling Power-to-Weight CalculatorFree online fitness & health calculator — instant results, no sign-up
Calculate sustained cycling watts per kilogram of rider body weight.
For general information only. This is not medical advice, diagnosis, dosing guidance or a treatment recommendation. Talk to a doctor or other qualified health professional about your health, pregnancy, or diet.
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About the Cycling Power-to-Weight Calculator
The Cycling Power-to-Weight Calculator divides sustained cycling power by rider body weight to report watts per kilogram (W/kg). It helps you compare power relative to body mass, a useful measure for climbing performance when efforts have comparable durations. With sustained power of 250 W and body weight of 75 kg, the result is 3.33 W/kg.
- Sustained power (W)
- The cycling power you can maintain over a chosen effort duration, entered in watts (W), with a default of 250 W.
- Body weight (kg)
- Your rider body mass, excluding the bicycle and equipment, entered in kilograms (kg), with a default of 75 kg.
Formula and method
R = P / m; with the default inputs, R = 250 W / 75 kg = 3.33 W/kg, rounded to two decimal places.
- RCycling power-to-weight ratio in watts per kilogram (W/kg).
- PSustained cycling power in watts (W).
- mRider body mass in kilograms (kg), which must be greater than zero.
Divide sustained power by rider body weight, then round the resulting watts-per-kilogram value to two decimal places for display. The calculation uses rider mass only and does not adjust for effort duration, bicycle mass, or riding conditions.
Worked example
These are the calculator's starting values and the results it actually produces for them.
Inputs
- Sustained power250 W
- Body weight75 kg
Results
- Power-to-weight ratio3.33 W/kg
How to use the Cycling Power-to-Weight Calculator
- 1Choose a sustained cycling effort and note its duration so later comparisons use a consistent basis.
- 2Enter its sustained power in watts; the default is 250 W.
- 3Enter your body weight in kilograms, excluding the bicycle and equipment; the default is 75 kg.
- 4Calculate the ratio by dividing power by body weight.
- 5Read the power-to-weight result: the default inputs produce 3.33 W/kg.
Reading your result
The Power-to-weight ratio output reports sustained watts for each kilogram of rider body weight. A result of 3.33 W/kg means that 250 W divided by 75 kg yields approximately 3.33 watts per kilogram. Higher values indicate more power relative to rider mass, but comparisons are meaningful only when effort duration and measurement methods are comparable. This output is not a speed prediction or a fitness-category rating.
Limitations
The calculator assumes the power value accurately represents a sustained effort and that body weight is measured correctly. It does not determine how long you can sustain that power or establish functional threshold power (FTP). Rider-only W/kg excludes bicycle and equipment mass, while actual cycling performance also depends on gradient, aerodynamics, wind, rolling resistance, altitude, and riding technique. Power-meter accuracy and calibration can affect the result. A higher ratio achieved through weight loss is not necessarily a sign of better health or improved performance, especially if fueling or sustainable power suffers.
Common questions
Should I enter FTP or power from another sustained effort?+
You can enter FTP if you want FTP-based W/kg, or use sustained power from another defined effort. Label the duration or testing method when tracking results, and avoid comparing a short-effort ratio directly with a threshold-based ratio.
Should my bicycle's weight be included in Body weight (kg)?+
No. This calculator uses rider body weight only. Bicycle and equipment mass matter for real-world climbing, but including them would produce a system-mass ratio rather than the rider-body-weight ratio this tool reports.
Does 3.33 W/kg tell me how fast I will ride?+
No. The default result of 3.33 W/kg describes 250 W relative to a rider weight of 75 kg. Speed also depends on terrain, total moving mass, aerodynamic drag, wind, and rolling resistance.
Can I compare my W/kg result with another cyclist's?+
Yes, if both results use rider-only weight and power measured over comparable durations with reasonably consistent equipment and testing methods. W/kg is particularly useful for climbing comparisons; on flatter roads, absolute power and aerodynamics often matter more.
Does the calculator save my information?+
Calculations run in your browser. While signed in, inputs and results are automatically recorded in account history; saving a result creates a separate saved record.
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Results are estimates for informational purposes and are not financial, medical or legal advice.