Critical Power Calculator

Estimate your Critical Power from maximal efforts and convert the output into practical training decisions.

Effort Inputs

Enter 2-3 best maximal efforts. Use durations that are clearly separated for better model stability.

Effort 1

Effort 2

Effort 3 (optional)

Results

Run calculation to see CP interpretation and next actions.

Critical Power Calculator Guide

Estimate your sustainable high-intensity anchor from maximal efforts and use it to structure interval targets.

What Critical Power tells you

Critical Power (CP) is a practical boundary between heavy sustainable work and efforts that deplete finite above-threshold capacity quickly.

Use CP as a decision anchor for interval pacing, not as a static identity number. Re-estimate it after meaningful training blocks.

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How this estimate is calculated

This tool uses two-point or three-point effort models, depending on available maximal efforts.

Critical Power model

W=CP⋅t+W′W = CP \cdot t + W^{\prime}
P=CP+W′tP = CP + \frac{W^{\prime}}{t}

Where:

  • WWtotal work during an effort (J)
  • tteffort duration (s)
  • CPCPcritical power (W)
  • W′W^{\prime}finite above-CP work capacity (J)

The model is sensitive to effort quality. Maximal efforts should be separated in duration and truly maximal.

If two efforts generate CP around 300 W, use that as your high-end sustainable reference for long intervals.

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Interpretation

  • CP is best used as a practical training anchor, not a fixed identity metric.
  • Model quality depends on maximal effort quality and duration spread.
  • Re-estimate CP periodically under consistent testing conditions.

What to Do Next

  • Use the Zone 2 calculator to map aerobic volume below high-intensity anchors.
  • Plan high-intensity intervals near CP and budget above-CP surges using W′ awareness.
  • Retest after a training block and compare trend direction, not one-off values.

Methodology

Version v1.0
Updated 2026-04-22
Owner Cycling Regimen Editorial

  • Work-Time Model

    Uses two/three-point Critical Power modelling from maximal efforts.

  • Assumption Transparency

    Warnings are shown when effort quality may reduce stability.

  • Training Integration

    Outputs are designed for pacing and interval decision support.

    Read source
About Our Calculation Approach

Frequently Asked Questions

Can I use any two efforts to estimate CP?

Yes, but reliability improves when efforts are maximal and clearly separated in duration (for example 3 and 12 minutes).

How often should I re-estimate CP?

A practical cadence is every 6-8 weeks, or after a meaningful training phase change.

Is CP the same as FTP?

They are related but not identical. CP is model-derived from maximal efforts, while FTP is a threshold estimate from specific protocols.

Disclaimer: This calculator provides estimates based on published exercise science models. Results are not medical advice. Individual physiology, health status, and environmental conditions affect real-world outcomes. Consult a qualified healthcare provider or certified coach before making training decisions based on these outputs.