FTP (Functional Threshold Power) is the highest average power in watts you can sustain for roughly an hour on the bike. It's the single most important number in cycling — most training programs, power zones, and race pacing decisions are built around it.

How is FTP estimated from a 20-minute test?

The standard protocol: warm up, then ride all-out for 20 minutes. Your FTP is approximately 95% of your 20-minute average power. The 5% discount accounts for the fact that you can push harder for 20 minutes than you could for a full hour.

What is watts per kilogram (W/kg)?

W/kg is your FTP divided by your bodyweight in kilograms. It's the key metric for climbing and relative performance. A 70 kg rider with 280W FTP has the same W/kg as a 90 kg rider with 360W — they'll climb at similar speeds despite very different power numbers.

What W/kg is considered good?

For men: 2.0-3.0 is a recreational rider, 3.0-4.0 is a solid amateur, 4.0-4.5 is cat 3/4 racer territory, 4.5-5.5 is cat 1/2, and 5.5+ approaches pro. For women subtract roughly 0.5 W/kg at each tier. These are FTP-based; sprint and 5-min W/kg show different distributions.

How often should I retest FTP?

Every 4-8 weeks if you're training consistently. More often during fast adaptation phases (new to training, returning from layoff), less often when plateaued. Many riders also use a ramp test or 8-minute test, which correlate well with the 20-minute method.

Does FTP change with bodyweight?

Your absolute FTP (watts) mostly reflects training state. Your W/kg also responds to bodyweight changes — losing fat raises W/kg without requiring more fitness. For climbers, W/kg improvements often come faster from losing 2-3 kg of body fat than from adding 20 watts of power.

FTP & Watts per Kilogram Calculator

Estimate your Functional Threshold Power from a cycling test, see your W/kg, and get training power zones.

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FTP and Watts per Kilogram Explained

FTP is the maximum power output you can sustain for about 60 minutes without going into oxygen debt. It sits at your lactate threshold — the intensity where blood lactate begins accumulating faster than your body can clear it. Everything below is sustainable; everything above has a countdown.

Watts per kilogram (W/kg) is what matters for climbing and for comparing riders of different sizes. Gravity doesn't care how many watts you push — it cares how many watts per kilogram of body mass you can move up the hill.

W/kg Classification (Male)

W/kgClassification

Under 2.5Novice / Untrained

2.5 – 3.25Cat 5 / Recreational

3.25 – 4.0Cat 3-4 / Good

4.0 – 4.75Cat 2 / Very Good

4.75 – 5.5Cat 1 / Elite Amateur

5.5+Professional

Running a 20-Minute Test

Warm up 20 minutes with a few short hard efforts
5-minute all-out effort to burn off top-end energy
10 minutes easy spinning
20 minutes as hard as you can sustain evenly
Cool down; record your 20-min average power

FTP = 20-min avg × 0.95. If you pace it poorly and fade, the estimate will be low.

FTP & Watts per Kilogram Calculator

FTP and Watts per Kilogram Explained

W/kg Classification (Male)

Running a 20-Minute Test

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