SuCalc
Health & Fitness

Cycling FTP & Power Zones Calculator

Updated Aug 27, 2026 Reviewed Aug 27, 2026
Enter a known FTP or estimate it from a field test, then calculate seven cycling power zones, sweet spot power, and watts per kilogram.

Threshold and training-zone estimate

Enter FTP or a field-test result

Enter the complete 20-minute average power; the editable default uses 95%.

Keep the field-test protocol's factor; it is not universal for every rider.

Training estimate, not a physiological diagnosis
Repeat comparable tests and use the zone system required by your coach or platform. Stop exercise and seek appropriate advice for concerning symptoms.

Result

Calculation summary

Enter values to see the result

Your result, breakdown, assumptions, and warnings will appear here.

Live power-zone preview

Seven zones around threshold

Z1Z2Z3Z4Z5Z6Z7FTP
Bars show representative target watts for the current seven-zone model and update with FTP or boundary changes.
Estimated FTP = 20-minute average × adjustment
Estimated FTP
261 W
Threshold ratio
3.48 W/kg
Sweet spot
230–245 W

How to use this calculator

  1. 1Choose a known FTP, a 20-minute test, or a 30-minute field-test result.
  2. 2Enter the relevant average power and adjust the test percentage only when your protocol calls for it.
  3. 3Review FTP, watts per kilogram, sweet spot power, and all seven zones.

Formula

estimated FTP = test average power × adjustment percentage

The default 20-minute estimate uses 95%; zone limits are calculated from rounded FTP.

Calculation steps

  • Estimate or accept FTP and apply the selected rounding increment.
  • Divide FTP by body mass in kilograms.
  • Apply six ordered boundaries to create seven watt ranges and sweet spot at 88–94%.

Worked example

A 275 W 20-minute average at 95% estimates 261 W FTP, or about 3.48 W/kg at 75 kg.

Assumptions

  • Field-test conversions are protocol estimates.
  • The default zones are a general seven-zone model.
  • Testing conditions and fitness can change FTP.
  • The tool does not prescribe training or medical limits.

Sources

Frequently asked questions

Why is the 20-minute default 95%?

It is a common field-test conversion, but the individual relationship varies, so it remains editable.

What does the 30-minute option use?

Enter the protocol-defined final 20-minute average and choose its prescribed adjustment.

Why do watt ranges not overlap?

The next whole-watt lower limit advances by one watt to avoid ambiguous assignments.

Are these heart-rate zones?

No, these zones are based on cycling power and FTP.

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