Functional Threshold Power Calculator

Work out functional threshold power instantly with clear inputs, formula shown and shareable results.

About Functional Threshold Power Calculator

FTP is the power you could hold for roughly an hour, and the standard field estimate is 95% of a maximal 20 minute effort. A 260 W twenty-minute average implies a 247 W FTP, which at 72 kg is 3.43 W/kg. Every training zone is then set as a percentage of FTP, which is why the test is repeated every six to eight weeks.

Formulas

FTP from a 20 minute test

FTP = 0.95 x 20 minute average power

Power to weight

W/kg = FTP / body mass

Worked example

With the default values below, Functional Threshold Power Calculator returns Functional Threshold Power of 247. Change any input above and every figure here is recalculated in your browser.

Inputs used

Average power over a 20 minute testminimum 1 W: 260 W
Body weightminimum 1 kg: 72 kg

Results

Functional Threshold Power: 247 W
Power To Weight At Threshold: 3.431 W/kg
Top Of Endurance Zone 2: 185 W
Threshold Zone 4 Range: 235-259 W

Step by step

1Values used
2FTP from a 20 minute test
3Power to weight
4Functional Threshold Power= 247 W
5Power To Weight At Threshold= 3.431 W/kg
6Top Of Endurance Zone 2= 185 W
7Threshold Zone 4 Range= 235-259 W

Assumptions and limits

The result is derived only from the 2 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
This is an estimate from population-average equations, not a medical or diagnostic assessment. Individual results vary with genetics, training history and technique. Seek advice from a qualified coach or clinician before making significant changes to training.
This is an estimate for general information and not professional medical advice. See the full disclaimer for the limits that apply to this kind of calculator.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

This is an estimate from population-average equations, not a medical or diagnostic assessment. Individual results vary with genetics, training history and technique. Seek advice from a qualified coach or clinician before making significant changes to training.

Frequently Asked Questions

Why the 95% factor?

Because a 20 minute maximal effort draws on anaerobic capacity that cannot be sustained for an hour. The 5% reduction approximates that contribution.

What W/kg is competitive?

Around 2.5-3 W/kg for a recreational rider, 3.5-4.5 for a strong club racer, and over 5.5 for a professional at threshold.