FTP Calculator
FTP from a hard timed effort — classic 20-min or 8-min factors. Click any i for detail.
Test
Test type
i
Test
20-minute average ×0.95 is common; 8-minute ×0.90 is an alternative. |
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20-min average power (W)
i
20-min W
Normalized or average watts for the full 20 minutes after warmup. |
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8-min average power (W)
i
8-min W
Average watts for an all-out 8-minute effort. |
How to use this calculator
- Choose 20-minute or 8-minute protocol.
- Enter average watts from that effort.
- Read estimated FTP.
- Rebuild training zones with your coach’s chart.
Results explained
Functional threshold power is roughly the highest power you can sustain about an hour. A practical estimate multiplies a maximal 20-minute average by 0.95 (or an 8-minute average by 0.90). Warmup quality, pacing, and altitude all matter — treat the number as a training anchor, not a lab VO2 measurement.
Quick reference: FTP tests
FTP ≈ 0.95 × 20-min W, or 0.90 × 8-min W.
| Item | Detail |
|---|---|
| 20-min factor | 0.95 |
| 8-min factor | 0.90 |
| Ramp tests | Different protocols — not this page |
| Zones | Often % of FTP |
Educational cycling estimate — not a coaching prescription.
How the estimate is built
FTP_20 = 0.95 × P_20; FTP_8 = 0.90 × P_8.
Example scenario
20-min average 280 W → FTP ≈ 266 W.
FAQ
Should I use normalized power?
Many coaches prefer average or NP from a clean effort — be consistent with how you built prior zones.
Indoor vs outdoor?
Both work; conditions differ. Retest in the environment you train most.
How often to retest?
Commonly every 4–8 weeks during a block, or when fitness clearly changes.
What about 60-minute tests?
A true hour effort can be used more directly; this page focuses on the shorter field tests.