Cycling FTP & Power-to-Weight Calculator
Estimate your cycling FTP from a 20-minute power test and turn it into a power-to-weight ratio in watts per kilogram — the number that drives climbing and sustained efforts — then see where it lands on the W/kg scale.
How it works
Functional Threshold Power (FTP) is the highest power you can hold for roughly an hour. Rather than ride flat-out for a full hour, most cyclists run a 20-minute test and take 95% of that average power as their FTP:
- FTP: 20-minute average power × 0.95, rounded to the nearest watt.
- Power-to-weight: FTP ÷ body weight in kilograms, giving watts per kilogram (W/kg).
Enter your weight in kilograms or pounds; the calculator converts it for the W/kg figure. The category bands below are approximate and broadly men-oriented — women's bands for the same label sit a little lower.
Worked example
A rider averages 300 W over a maximal 20-minute test. FTP = 300 × 0.95 ≈ 285 W. At a body weight of 75 kg, that's 285 ÷ 75 ≈ 3.8 W/kg, which falls in the Moderate band.
Power-to-weight categories
A rough guide to power-to-weight at FTP, in watts per kilogram. These bands are approximate and men-oriented; women's bands for the same label sit a little lower, so use them as a broad reference rather than a strict standard:
| Category | Power-to-weight (W/kg) |
|---|---|
| Untrained | < 2.0 |
| Fair | 2.0 – 2.9 |
| Moderate | 3.0 – 3.9 |
| Good | 4.0 – 4.9 |
| Very good | 5.0 – 5.9 |
| Exceptional | 6.0+ |
Approximate general bands; women's category thresholds are lower than the men-oriented values shown.
Interpreting your number
Raw FTP in watts is the best single marker of your engine — track it over a training block to see fitness change. Power-to-weight (W/kg) tells you how that power translates on climbs and long sustained efforts, where carrying less weight for the same watts helps. To put the effort in context, pair this with the Heart Rate Zone Calculator and gauge aerobic fitness with the VO₂ Max Calculator.
Frequently asked questions
What is FTP in cycling?
- FTP — Functional Threshold Power — is the highest average power, in watts, that you can sustain for about an hour. It marks the boundary between sustainable aerobic effort and the fast-fatiguing zone above it, and it's the number most structured cycling training plans are built around.
Why is FTP 95% of 20-minute power?
- A true one-hour maximal effort is hard to pace and exhausting to repeat, so the common shortcut is a 20-minute test. Because you can hold more power for 20 minutes than for a full hour, FTP is estimated as 95% of your 20-minute average power to approximate the one-hour figure.
What is a good power-to-weight ratio?
- Power-to-weight at FTP (watts per kilogram) is the key climbing and endurance metric. As a rough men-oriented guide: under 2 W/kg is untrained, 3–4 is moderate to good, 4–5 is strong club-rider territory, and 5+ approaches very good to elite. Women's bands for the same label sit a little lower.
How do I do a 20-minute FTP test?
- After a thorough warm-up (often including a short hard opener), ride as hard as you can sustain evenly for 20 minutes on a flat road or trainer, recording your average power. Avoid going out too fast. Multiply that average by 0.95 to estimate FTP.
Should I use FTP per kg or raw watts?
- Both matter. Raw watts decide flat and time-trial speed where aerodynamics dominate, while watts per kilogram drives climbing and any sustained effort against gravity. Track raw FTP to see fitness changes and W/kg to compare riders or gauge climbing ability.
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Disclaimer. This is an estimate for general information only, not medical advice. A ramp test or a full one-hour effort gives a more accurate FTP than the 20-minute shortcut. Consult a qualified professional before strenuous fitness testing, especially if you have any health concerns.