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Critical Power Calculator

Calculate your Critical Power (CP) and W\' to determine sustainable power output and anaerobic work capacity.

Critical Power Calculator

Estimate your critical power (CP) and anaerobic work capacity (W′) using two maximal efforts.

Understanding the Inputs

Measure efforts consistently for accurate CP estimates

  • Power 1 (watts): Average power from your shorter maximal effort (e.g., 3–5 minutes). Use calibrated power meter data.
  • Duration 1 (minutes): Duration of the first effort in minutes. Convert seconds to decimal (e.g., 4 minutes 30 seconds = 4.5).
  • Power 2 (watts): Average power from your longer maximal effort (e.g., 12–20 minutes). Keep conditions consistent with the first test.
  • Duration 2 (minutes): Duration of the second effort in minutes. Ensure it is meaningfully longer than duration 1 for accurate results.

Related Calculators

Explore additional performance analytics

Power-to-Heart Rate Efficiency

Analyse power and heart rate coupling for training readiness.

Anaerobic Capacity

Estimate high-intensity energy reserves for repeated efforts.

Maximal Aerobic Speed

Translate aerobic capacity into running training zones.

Oxygen Debt (EPOC)

Understand post-exercise oxygen needs after intense sessions.

Complete Guide: Using Critical Power in Training

Critical power (CP) helps separate sustainable aerobic output from finite anaerobic capacity (W′). Testing with two maximal efforts enables precise training zone prescription. Use CP for pacing time trials, planning interval intensity, and monitoring long-term progress. Track W′ to gauge anaerobic reserves for surges and sprint finishes. Combine consistent testing, balanced training distribution, and adequate recovery to maximise performance gains.

Frequently Asked Questions

Detailed, SEO-oriented answers

What is critical power (CP)?

Critical power (CP) is the highest power output you can sustain over a longer duration without fatigue rapidly increasing. It reflects aerobic endurance capacity and is typically determined from two or more maximal efforts.

What is W′ (W prime)?

W′ represents your finite anaerobic work capacity above CP. It is the energy reserve you can use for surges, attacks, and short high-intensity efforts before needing to recover below CP.

How do I collect data for CP testing?

Perform two or more all-out efforts at different durations (e.g., 3–5 minutes and 12–20 minutes). Record average power and duration for each effort. The calculator uses these inputs to estimate CP and W′.

Can I use more than two data points?

This calculator uses two data points for simplicity. Using three or more maximal efforts improves accuracy. For advanced analysis, consider software that supports multi-point CP modelling.

How often should I retest critical power?

Retest every 6–8 weeks or after completing a focused training block. Retesting helps update training zones and monitor adaptations in both aerobic and anaerobic systems.

What is a good CP value?

CP varies by rider size, discipline, and training background. Recreational cyclists may have CP values under 250 W, while competitive cyclists often exceed 300 W. Track progress relative to your baseline.

How can I increase my CP?

Combine endurance rides, tempo/threshold intervals, and VO₂ max efforts while progressively increasing training volume. Adequate recovery, nutrition, and strength training also support CP improvements.

How can I improve W′?

Target high-intensity interval training above CP, sprint intervals, and repeated anaerobic efforts with controlled recovery. Ensure you also build aerobic fitness to replenish W′ more efficiently.

Is CP the same as FTP?

Functional Threshold Power (FTP) is similar but not identical. FTP is typically defined as 95% of a 20-minute effort or 60-minute power. CP is derived mathematically from multiple efforts and can be slightly higher or lower than FTP depending on individual physiology.

Can I use heart rate instead of power?

Accurate CP and W′ calculations require consistent power data. Heart rate responds more slowly and is influenced by many factors, so it is not suitable for CP calculations without power measurements.

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Critical Power Calculator

Calculate your Critical Power (CP) and W\' to determine sustainable power output and anaerobic work capacity.

How to use Critical Power Calculator

Step-by-step guide to using the Critical Power Calculator:

  1. Enter your values. Input the required values in the calculator form
  2. Calculate. The calculator will automatically compute and display your results
  3. Review results. Review the calculated results and any additional information provided

Frequently asked questions

How do I use the Critical Power Calculator?

Simply enter your values in the input fields and the calculator will automatically compute the results. The Critical Power Calculator is designed to be user-friendly and provide instant calculations.

Is the Critical Power Calculator free to use?

Yes, the Critical Power Calculator is completely free to use. No registration or payment is required.

Can I use this calculator on mobile devices?

Yes, the Critical Power Calculator is fully responsive and works perfectly on mobile phones, tablets, and desktop computers.

Are the results from Critical Power Calculator accurate?

Yes, our calculators use standard formulas and are regularly tested for accuracy. However, results should be used for informational purposes and not as a substitute for professional advice.