Cardio
As of 2026-04-24
How Cycling Power & FTP Zone Calculator works
Methodology for the Cycling Power & FTP Zone Calculator: formulas, coefficients, data sources, assumptions, and known limitations.
Scope
Computes the seven Coggan power training zones from FTP or from a 20-minute test result.
Formula
FTP = 0.95 * power_20min. Zone_n_range = coggan_pct_range_n * FTP.
Coefficients
| Parameter | Value | Note |
|---|---|---|
| Z1 Active Recovery | < 55% FTP | |
| Z2 Endurance | 56–75% FTP | |
| Z3 Tempo | 76–90% FTP | |
| Z4 Lactate Threshold | 91–105% FTP | |
| Z5 VO2 Max | 106–120% FTP | |
| Z6 Anaerobic | 121–150% FTP | |
| Z7 Neuromuscular | > 150% FTP |
Data sources
- Allen H, Coggan A, McGregor S. Training and Racing with a Power Meter. 3rd ed. VeloPress, 2019. — Publisher page; source of the seven-zone Coggan model.
- Coggan A. Power training zones for cycling. TrainingPeaks (author reference). — Coggan's canonical public reference for the zone definitions.
- Borszcz FK, Tramontin AF, Bossi AH, Carminatti LJ, Costa VP. Functional threshold power in cyclists: validity of the concept and physiological responses. Int J Sports Med. 2018;39(10):737-742. — PMID 29801179. Validation study on the 20-min x 0.95 FTP protocol.
Assumptions
- Power meter is calibrated; 20-min test effort was honest.
Approximation range
FTP from 20-minute x 0.95 slightly over-estimates true FTP for well-trained cyclists; under-estimates for sprinters.
Limitations
- Zones drift as fitness changes — re-test FTP every 6–8 weeks.
- Indoor FTP can be 5–10% lower than outdoor FTP for the same rider.
Reproducibility
20-min power 300 W. FTP = 285 W. Z2: 0.56*285–0.75*285 = 160–214 W.
Change log
- 2026-04-24: methodology page first published.
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