Health & Medicine · Fitness · Performance Metrics
Functional Threshold Power (FTP) Calculator
Estimate your Functional Threshold Power (FTP) from a 20-minute test, ramp test, or hour-long best power output for cycling training zones.
Calculator
Formula
P_20 is the average power in watts over a maximal 20-minute effort. The 0.95 correction factor accounts for the fact that a 20-min maximal power slightly overestimates 60-min sustainable power. P_ramp is the peak 1-minute power achieved in a ramp test, with 0.75 being the standard conversion factor. P_60 is the average power held for a full 60-minute maximal effort, which directly equals FTP.
Source: Allen & Coggan, 'Training and Racing with a Power Meter', 3rd ed. (2019); British Cycling Ramp Test protocol.
How it works
FTP is defined as the highest average power a cyclist can maintain for 60 minutes without fatiguing. Because a true 60-minute all-out test is exhausting, most riders use shorter proxy tests. The most common is the 20-minute test, where you ride as hard as possible for 20 minutes and multiply the average power by 0.95 — accounting for the slightly higher power output possible over 20 versus 60 minutes.
The ramp test, popularised by platforms such as Zwift and British Cycling, increases resistance every minute until failure. You multiply the highest 1-minute power achieved by 0.75, a conversion factor validated by British Cycling's coaching science team. If you have a verified 60-minute race or time-trial power file, that average power equals your FTP directly (×1.00).
Once FTP is established, training zones — expressed as percentages of FTP — are calculated following the seven-zone model from Allen and Coggan. These zones prescribe exact physiological stimulus: Zone 1 promotes recovery, Zone 2 builds aerobic base, Zones 3–4 target lactate threshold, and Zones 5–7 develop VO2 max and neuromuscular power.
Worked example
Scenario: A cyclist completes a 20-minute test and sustains an average of 280 W. Their body weight is 72 kg.
Step 1 — Calculate FTP: FTP = 0.95 × 280 = 266 W
Step 2 — Calculate W/kg: 266 ÷ 72 = 3.69 W/kg (Category 4 racer / solid amateur level).
Step 3 — Training Zones:
- Zone 1 (Active Recovery): up to 146 W (≤55%)
- Zone 2 (Endurance): 147–200 W (56–75%)
- Zone 3 (Tempo): 201–239 W (76–90%)
- Zone 4 (Lactate Threshold): 240–279 W (91–105%)
- Zone 5 (VO2 Max): 280–319 W (106–120%)
This rider should target Zone 2 for long base rides (3–5 h) and Zone 4 intervals (e.g., 2×20 min) to most efficiently raise their FTP.
Limitations & notes
FTP is a functional estimate, not a laboratory measurement. The 0.95 correction factor for the 20-minute test is a population average — some riders' correction is closer to 0.92 or 0.98 depending on their individual physiology and pacing strategy. A badly paced 20-minute test (going out too hard) will inflate FTP and push training zones unrealistically high. The ramp test tends to favour riders with strong anaerobic capacity. Fatigue, altitude, heat, and hydration status all affect test results. FTP should be retested every 4–8 weeks during a training block or after any significant fitness change. This calculator does not replace a sport-science laboratory VO2 max test or lactate threshold assessment.
Frequently asked questions
How often should I retest my FTP?
Most coaches recommend retesting every 4–8 weeks during a structured training block. If you complete a training block with consistent Zone 2 and threshold work, a measurable increase of 3–8% in 8 weeks is realistic for intermediate riders. Retest whenever you feel your current zones no longer reflect your fitness — efforts that used to feel hard in Zone 4 now feel easy, for example.
Is the 20-minute test or the ramp test more accurate?
Neither is universally superior. The 20-minute test is more representative of sustained power for most road cyclists, but it requires precise pacing and mental toughness. The ramp test is easier to execute and less daunting, making it popular for beginners and for indoor platforms like Zwift. Riders with a strong sprint or anaerobic capacity may find the ramp test overestimates their FTP, while pure endurance riders may find it slightly underestimates it. Use the same test format consistently so your progress comparisons are valid.
What is a good FTP for a cyclist?
FTP relative to body weight (W/kg) is the most useful benchmark. Untrained beginners typically sit around 1.5–2.5 W/kg. Recreational cyclists range from 2.5–3.5 W/kg. Category 3–4 amateur racers often hit 3.5–4.5 W/kg. Elite amateur and professional cyclists generally exceed 5.0 W/kg, with top Grand Tour climbers exceeding 6.0 W/kg. These benchmarks vary by age, sex, and training history — focus on improving your own baseline rather than comparing to others.
Can I use FTP for running or triathlon training?
FTP is a cycling-specific metric. For running, the analogous metric is Critical Speed (CS) or Functional Threshold Pace (FTPa), which is estimated from a 30-minute time trial. For swimming, Critical Swim Speed (CSS) serves the same role. Triathletes who train with power meters on the bike can use cycling FTP normally, but should use sport-specific threshold metrics for run and swim training — power zones from cycling do not transfer directly to other disciplines.
Why does my FTP drop after a hard race or training week?
Accumulated fatigue suppresses power output, so testing FTP when you are tired will give an artificially low reading. Most coaches recommend testing FTP only after a proper recovery week (reduced volume by 40–60%) so your neuromuscular and metabolic systems are fully recovered. A true drop in FTP — one that persists even after adequate rest — may signal overtraining, illness, or inadequate nutrition and sleep.
Do I need a power meter, or can I use heart rate?
A power meter is required for accurate FTP testing and power-based training zones. Heart rate is affected by factors like temperature, caffeine, hydration, and stress, making it an unreliable standalone metric for setting intensity zones. However, once you know your FTP power zones, you can observe the corresponding heart rate ranges over multiple rides and use those as secondary reference points when a power meter is unavailable (e.g., outdoor rides on borrowed bikes). Heart rate at threshold for most cyclists is approximately 88–92% of maximum heart rate.
Last updated: 2025-01-30 · Formula verified against primary sources.