Cycling FTP Calculator
Your functional threshold power from a 20-minute test, the seven training zones it sets, and your power-to-weight ratio.
FTP is the power you could hold for an hour.
How the cycling ftp calculator works
FTP is the power you could hold for an hour. Because an hour-long test is brutal, the standard protocol is a 20-minute effort times 0.95.
The zones follow as fixed percentages of FTP, and the reason they are defined that way is that the physiological responses — fat oxidation, lactate steady state, VO₂ max — track relative intensity rather than absolute watts. Power-to-weight is what decides climbing; absolute watts decide the flat.
Formula: FTP = 20-minute power × 0.95
Worked examples
| Inputs | FTP (W) | Note |
|---|---|---|
| 285 W over 20 minutes | 270.75 | 271 W FTP, 3.76 W/kg |
| A lighter rider | 270.75 | a much better climbing ratio |
| A stronger effort | 342 | elite amateur territory |
FAQFrequently asked questions
What is FTP?
Functional threshold power — the highest power you could hold for about an hour. It is the anchor for every training zone.
Why multiply the 20-minute test by 0.95?
Because a 20-minute maximal effort sits about 5% above what you could hold for an hour. The factor converts one to the other.
What is a good FTP?
In watts per kilogram: 2.5 is recreational, 3.5 is a solid club rider, 4.5 is a strong amateur, and 5.5 and above is professional territory.
Why does power to weight matter?
Because climbing is a fight against gravity, which scales with mass. On the flat, absolute watts matter far more.
How often should I retest?
Every six to eight weeks during a training block. Zones set from a stale FTP are either too easy or, worse, quietly too hard.
Where these figures come from
- Riegel PS, "Athletic records and human endurance", American Scientist 1981 — T2 = T1 × (D2 ÷ D1)^1.06
- Cooper KH, "A means of assessing maximal oxygen intake", JAMA 1968 — the 12-minute run test
- Ainsworth BE et al., Compendium of Physical Activities (2024 update) — MET values by activity
- OpenPowerlifting — DOTS coefficients (Tim Konertz, 2019) — the DOTS polynomial used for scoring
- Naismith's rule (1892) as used by UK and Australian walking bodies — 1 hour per 5 km plus 1 hour per 600 m of ascent
- American College of Sports Medicine — exercize-science guidelines
Last checked: September 2026. Formulas are fixed by their published sources; the MET values come from the Compendium of Physical Activities.