Why multiply by 0.95 instead of using the 20-minute power directly?

A maximal 20-minute effort typically produces slightly higher power than an athlete can sustain for a full hour. The 0.95 factor estimates the power sustainable at lactate threshold over 60 minutes by accounting for the shorter test duration and pacing strategy.

Does the 0.95 multiplier work for everyone?

Individual physiology varies. Some cyclists find their true hour power closer to 93% or 97% of their 20-minute best. The 0.95 value represents a population average and serves as a starting point for structured training, often refined through additional testing or real-world validation.

How often can a 20-minute FTP test be performed?

Testing frequency depends on training phase and recovery capacity. Many cyclists retest every 6–12 weeks to track fitness changes, allowing adequate recovery and adaptation between assessments. More frequent testing may interfere with training adaptation.

What conditions affect the accuracy of a 20-minute test?

Wind, gradient, temperature, altitude, and recent training stress all influence power output. Controlled indoor trainer tests minimize environmental variables, while outdoor tests require consistent routes and weather. Fatigue from prior workouts or inadequate warm-up also impacts results.

Can this FTP estimate be used to set training zones?

Many training frameworks define zones as percentages of FTP. The estimate from this calculator provides a reference point; athletes often adjust zones based on perceived exertion, heart rate, and performance in key workouts. Individual responses to intensity vary.

Cycling

FTP Calculator (from 20-Min Test)

Estimate Functional Threshold Power by applying a 0.95 factor to your 20-minute test result.

Last updated: 22 April 2026

What this tool does

This calculator estimates Functional Threshold Power (FTP) by applying the standard 0.95 conversion factor to a 20-minute maximal cycling test, following the protocol introduced by Andrew Coggan and Hunter Allen. It takes a single input—average power sustained during a 20-minute all-out effort—and returns estimated FTP in watts, representing the power output an athlete can theoretically sustain for one hour. The 5% reduction accounts for the typical difference in fatigue accumulation between 20-minute and 60-minute maximal efforts, making this a widely adopted field-test alternative to a full one-hour FTP test.

Inputs

Result

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Formula Used

FTP = 0.95 \times P_{20}

P_{20}

Best 20-minute average power in watts

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How FTP Calculator (from 20-Min Test) works

This calculator derives Functional Threshold Power (FTP) from a 20-minute all-out test by applying a 0.95 multiplier to the average power output recorded during that effort. The result estimates the power an athlete can sustain for approximately one hour, expressed in watts. The tool accepts a single input—the average power held for 20 minutes—and returns the calculated FTP value.

The formula

FTP = 20-minute average power × 0.95

The 0.95 scaling factor accounts for the physiological difference between maximal 20-minute efforts and true one-hour threshold performance. This approach was popularized by Andrew Coggan and Hunter Allen in Training and Racing with a Power Meter, where the 20-minute test protocol became a practical alternative to full 60-minute FTP assessments.

Where this method is most accurate

The 0.95 multiplier assumes a well-executed maximal 20-minute effort performed in conditions similar to those in which the athlete typically trains or races. Accuracy depends on proper pacing: starting too conservatively or fading significantly in the final minutes skews the input data. The protocol works best for cyclists with a trained aerobic base and familiarity with sustained high-intensity efforts. Environmental factors—wind, gradient, temperature—that differ markedly between test and training conditions introduce variability. The method does not account for individual physiological profiles; some athletes' 20-minute power sits closer to 93% or 97% of true hour power.

What this tool does not do

This calculator performs arithmetic on user-provided test data; it does not prescribe training zones, diagnose fitness level, or recommend changes to an athlete's program. It does not validate whether the input represents a true maximal 20-minute effort, adjust for fatigue or environmental conditions, or determine readiness to race. The tool provides a single estimate based on one widely used conversion factor and does not substitute for individualized coaching or physiological testing.

Disclaimer

This tool is for educational and informational purposes only. It is not medical, training, or health advice. Consult a qualified coach, sports scientist, or healthcare provider before beginning or modifying any training program. Individual results vary based on fitness, experience, and biomechanics. Use of this calculator does not create a professional relationship.

Questions

Why multiply by 0.95 instead of using the 20-minute power directly?: A maximal 20-minute effort typically produces slightly higher power than an athlete can sustain for a full hour. The 0.95 factor estimates the power sustainable at lactate threshold over 60 minutes by accounting for the shorter test duration and pacing strategy.
Does the 0.95 multiplier work for everyone?: Individual physiology varies. Some cyclists find their true hour power closer to 93% or 97% of their 20-minute best. The 0.95 value represents a population average and serves as a starting point for structured training, often refined through additional testing or real-world validation.
How often can a 20-minute FTP test be performed?: Testing frequency depends on training phase and recovery capacity. Many cyclists retest every 6–12 weeks to track fitness changes, allowing adequate recovery and adaptation between assessments. More frequent testing may interfere with training adaptation.
What conditions affect the accuracy of a 20-minute test?: Wind, gradient, temperature, altitude, and recent training stress all influence power output. Controlled indoor trainer tests minimize environmental variables, while outdoor tests require consistent routes and weather. Fatigue from prior workouts or inadequate warm-up also impacts results.
Can this FTP estimate be used to set training zones?: Many training frameworks define zones as percentages of FTP. The estimate from this calculator provides a reference point; athletes often adjust zones based on perceived exertion, heart rate, and performance in key workouts. Individual responses to intensity vary.

Sources & Methodology

FTP = 20-minute average power × 0.95. This conversion factor, introduced by Andrew Coggan and Hunter Allen, estimates one-hour sustainable power from a shorter maximal test. The 0.95 multiplier reflects typical fatigue accumulation differences between 20-minute and 60-minute efforts.

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