FTP Calculator — Convert 20-Min Test to FTP and W/kg
You did an FTP test and want to know your real threshold power? That is exactly what the Coggan 0.95 factor is for. With the calculator below you only need three inputs — you immediately get your FTP, your watts per kilogram and your classification in the Coggan spectrum.
The calculator supports three test methods: 20-min test (classic, most accurate), 8-min test (shorter, slightly less accurate) and ramp test (Zwift style, most comfortable). How to run the test cleanly is covered in detail in How to do an FTP test right.
How does the calculator work?
FTP (Functional Threshold Power) is the power you could theoretically hold steadily for 60 minutes. Nobody voluntarily does a 60-min all-out test, so approximations are used. The most famous comes from Andy Coggan:
Example: 285 W × 0.95 = 271 W FTP
The 0.95 factor is empirically derived — from thousands of athlete tests we know that 60-min power approximately equals 95% of 20-min power. For some athletes the factor does not fit precisely (more on that below), but it is a solid baseline.
The alternative methods
Three common test protocols:
- 20-min test (Coggan classic): FTP = 20-min power × 0.95. Considered the gold standard. Effort duration closest to true FTP duration.
- 8-min test (Carmichael): FTP = 8-min power × 0.90. Easier to execute but less accurate. Typically overestimates for VO2max-strong athletes.
- Ramp test (Zwift / TrainerRoad style): FTP = 1-min peak power × 0.75. Maximum comfort but the least accurate method. Use rather as a rough estimate.
Watts per kilogram — why W/kg matters more than absolute watts
An FTP of 300 W sounds like a lot. But whether that suffices in a race depends on your weight. 300 W at 90 kg equals 3.33 W/kg — solid amateur Cat 4 value. 300 W at 65 kg equals 4.62 W/kg — Cat 1 / Cat 2 level.
When climbing, W/kg is almost all that matters because you have to overcome your own weight. On flat terrain and at high speed, absolute watts become more important (air resistance). For most training purposes, W/kg is the more meaningful metric.
The Coggan classification
Andy Coggan created a table mapping FTP values in W/kg to performance levels. The key tiers for men and women:
| Category | W/kg (M) | W/kg (F) | Reference |
|---|---|---|---|
| World-Class | ≥ 5.65 | ≥ 5.15 | International Pro |
| Exceptional | ≥ 5.05 | ≥ 4.55 | Cat 1 / Conti Pro |
| Excellent | ≥ 4.55 | ≥ 4.10 | Cat 1 / Cat 2 |
| Very Good | ≥ 4.05 | ≥ 3.65 | Cat 2 / Cat 3 |
| Good | ≥ 3.55 | ≥ 3.20 | Cat 3 / Cat 4 |
| Moderate | ≥ 3.05 | ≥ 2.75 | Cat 4 / Cat 5 |
| Fair | ≥ 2.55 | ≥ 2.30 | Cat 5 / Amateur |
| Untrained | < 2.55 | < 2.30 | Beginner |
Important: this table is a statistical average. It does not mean you will race in a specific category — that depends on race tactics, sprint ability, endurance and many other factors.
Where the 0.95 factor does not fit
The Coggan 0.95 factor is an approximation, not a natural constant. There are two athlete types where it does not fit well:
- Very endurance-oriented athletes (ultra-triathletes, climbers): Can often hold threshold longer than 60 minutes. Their real FTP sits closer to 96–97% of 20-min power. The standard factor underestimates them.
- VO2max-strong sprinters: Have lots of anaerobic capacity, can "top up" short efforts significantly. For them, real FTP sits closer to 92–93% of 20-min power. The standard factor overestimates them.
For most amateur athletes, 0.95 is a valid estimate. If in doubt, do an additional 60-min tempo test (e.g. a tempo session or a 40-km time trial) and cross-check the values.
Typical mistakes during the FTP test
- Warm-up too short: at least 20–30 minutes progressively building, with 2–3 activation sprints. Otherwise your power output in the first test minute is too low.
- Starting too fast: the most common trap. Pacing is everything — hold the first 5 minutes 5% below target pace, then build to target power.
- Wrong power meter: pedal vs. hub vs. crank power meters can differ by 5–10%. Always use the same power meter for all tests.
- Not rested: an FTP test requires full form. At least 48 hours of recovery before the test, ideally 72.
- Wrong environment: indoor (smart trainer) is 5–15 W lower than outdoor (same power feels harder). Keep them separate, do not mix.
How to use the calculator in practice
Four use cases:
- Derive training zones: from your FTP your 5 or 7 Coggan zones follow automatically (Z2 Endurance: 56–75% FTP, Z3 Tempo: 76–90%, Z4 Threshold: 91–105%, etc.). The training zones calculator does exactly that.
- Track training progress: test every 6–8 weeks. If FTP grows, your training works. If not, recalibrate.
- Plan race strategy: on climbs, W/kg is decisive. With your current value you can roughly estimate what is possible on a given climb.
- Compare with others: the Coggan table helps realistically assess where you stand in the spectrum — without artificially flattering or beating yourself up.
Do the test not just once. First test? Write down the result and retest in 6 weeks — same protocol, same time of day, same power meter. Only the comparison shows whether your training works.
Conclusion
FTP is the most important power metric in cycling — it defines your training zones, race strategy and training progress. The calculator here gives you all relevant values from three simple inputs (test power, weight, sex): FTP, W/kg, Coggan classification.
Important: the calculated value is only as good as your test. Invest in a clean protocol (proper warm-up, good pacing, rested state) and compare regularly — then you have a reliable base for your training.
Why FTP = 20-min power × 0.95?
What is a good W/kg value for amateur athletes?
Which FTP test is most accurate?
Why do men and women tables differ?
How often should I retest my FTP?
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