Critical Power (CP) & W' Calculator - Anaerobic Battery Modeling
Determine your fatigue-free aerobic floor and calculate how many seconds you can survive above threshold before your W' battery depletes.
How to Use Critical Power & W' in 3 Simple Steps
Step 1: Upload
Drag & drop your .FIT, .GPX, or .TCX activity file. All processing is 100% private in your browser.
Step 2: Process
FitCrop inspects telemetry streams, removes anomalies, recalibrates metrics, or fixes binary checksums.
Step 3: Export
Download your clean Strava, Garmin, and Zwift compatible file with 1 click. Zero server wait.
Frequently Asked Questions
What is the difference between Critical Power (CP) and FTP?
FTP is estimated 1-hour power, while CP is the mathematical asymptote of the hyperbolic power-duration curve. CP represents the true physiological boundary between steady-state and non-steady-state fatigue.
What is W' (W-Prime) in cycling?
W' is the finite amount of work (measured in kilojoules) you can perform above your Critical Power before muscular exhaustion forces you to slow down.