# Cycling Power to Weight Calculator

> Work out your cycling power-to-weight ratio in W/kg and W/lb, and the power or body weight needed to reach a target W/kg.

Category: Health & fitness · Applies to: Worldwide · Last updated: 2026-10-29
Interactive calculator: https://calculators.geekmidst.com/calculators/cycling-power-to-weight-calculator

Power-to-weight is your sustained power in watts divided by your body weight in kilograms. It is the number that matters most when the road goes uphill.

Also called: Watts per kilo calculator, W/kg calculator.

## Inputs
- Power (unit W; default 250)
- Body weight (default 70)
- Weight in (options: kg, lb; default kg)
- Target power-to-weight (unit W/kg; default 4)

## Results
- Power-to-weight
- Watts per pound
- Power needed for the target at this weight
- Weight for the target at this power (in your unit)

## Formula

```
W/kg = Power ÷ Body mass (kg);  Power for target = Target × Mass;  Mass for target = Power ÷ Target
```

Where:
- Power: sustained output in watts
- Mass: rider body mass (1 lb = 0.45359237 kg)

## Worked example
1. 250 W ÷ 70 kg = 3.57 W/kg.
2. 4 W/kg at 70 kg needs 4 × 70 = 280 W.
3. At 250 W, 4 W/kg would mean 250 ÷ 4 = 62.5 kg.

**Result:** A 70 kg rider holding 250 W produces 3.57 W/kg; reaching 4 W/kg takes another 30 W.

## What the result means

W/kg compares riders of different sizes on climbs. On flat roads absolute watts and aerodynamics matter more, so a heavier rider with lower W/kg can still be faster.

## Assumptions and limits
- Body weight only; the bike’s weight is not included.
- Power is a sustained figure from the same kind of test each time.
- Losing weight to raise W/kg can also cost power; any weight-loss plan should be discussed with a qualified professional.

## Questions

### Should I include the bike in the weight?

Convention is body weight only. Total system weight matters for climbing-speed estimates, which need a separate physics model.

### Which power figure should I use?

Use the same duration each time, for example your FTP or best 20-minute power, so that comparisons are fair.

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Source: GM¹X CalcVerse — https://calculators.geekmidst.com/calculators/cycling-power-to-weight-calculator