Cycling FTP & Power Zone Calculator

Turn One Test Effort Into a Full Set of Training Zones

FTP (Functional Threshold Power) is the single number most structured cycling training is built around, but almost nobody actually rides a full 60-minute time trial to measure it directly. Instead, riders use a shorter proxy test — a 20-minute effort, a ramp test, or a couple of hard 8-minute efforts — and apply a correction factor to estimate it. This calculator does that conversion for whichever test you did, then breaks the result into the 7 Coggan power zones every major platform (TrainingPeaks, Zwift, WKO) uses for structured workouts.

How to use it

• Pick the test you actually did: a 20-minute effort, a ramp test, an 8-minute effort, a full 60-minute test, or just enter a known FTP directly.
• Enter the average power (or best 1-minute power for a ramp test) from that effort in watts.
• Add your body weight to also see your FTP in W/kg, along with a rough sense of where that puts you against typical rider categories.
• Use the zone table to set up structured intervals — endurance rides in Zone 2, threshold intervals in Zone 4, VO2 max efforts in Zone 5, and so on.

Real-world use cases

Setting up a new bike computer or trainer app with the correct power zones after a fresh FTP test, instead of guessing at round numbers. Checking whether a recent ramp test result lines up with a 20-minute test done a few weeks earlier, since the two use different correction factors. Planning an interval session and needing the exact wattage range for "sweet spot" or "threshold" without doing the percentage math by hand every time.

Frequently asked questions

How accurate is a 20-minute FTP test?

The 0.95 multiplier is a well-established estimate, but it assumes a genuinely maximal, evenly-paced 20-minute effort. Pacing too conservatively or fading in the last few minutes will understate your true FTP.

What's the difference between FTP from a ramp test and a 20-minute test?

A ramp test measures your best 1-minute power in the final stage before failure and applies a steeper 0.75 correction, since it reflects a shorter, harder effort rather than sustained threshold pacing. The two methods can give slightly different numbers for the same rider — that's normal, not an error.

What is a good FTP in watts per kilogram?

Roughly: under 2.0 W/kg is untrained, 2–3 is recreational, 3–4 is a fit club rider, 4–5 is a strong Category 3 racer, 5–6 is Category 1–2 level, and 6+ is professional/elite territory. These bands are approximate and vary by rider weight and discipline.

Do power zones change as my FTP improves?

Yes — zones are always a percentage of your current FTP, so retesting every 6–8 weeks (or after a training block) and updating your number keeps every zone, and every workout built around it, accurate.

Why does Zone 4 matter so much for training?

Zone 4 (91–105% of FTP) sits right around your lactate threshold, which is why "threshold intervals" in this range are one of the most common and effective ways to directly raise your FTP over time.