Critical Power Calculator

How to calculate Critical Power?

Critical Power (CP) identifies the boundary between heavy and severe exercise intensities using a linear model of work over time.

Formula: CP = (W2 - W1) / (t2 - t1) where W is Joules and t is seconds.

Using the Critical Power calculator: an example

Example: An athlete completes a 3-minute test at 400W and a 12-minute test at 320W.

Step-by-step calculation:

1. Convert durations to seconds (180s and 720s)
2. Calculate total work (72kJ and 230.4kJ)
3. Apply the formula to find CP (293W) and W' (19.2kJ)

Frequently Asked Questions

What does W' (W-prime) mean?

W-prime represents your finite anaerobic energy reserve available for work performed above your Critical Power.

How often should I test?

Athletes typically re-test every 8-12 weeks or after a dedicated training block to update their training zones.

Why use two tests?

Two tests of different durations allow the model to separate your aerobic contribution (CP) from your anaerobic capacity (W').