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Training Load Calculator — CTL, ATL & TSB
Estimate your fitness (CTL), fatigue (ATL) and form (TSB) from training data.
How We Calculate This
Performance Management Chart
The PMC model uses exponentially weighted moving averages:
- CTL (Fitness) = 42-day exponential moving average of daily TSS
- ATL (Fatigue) = 7-day exponential moving average of daily TSS
- TSB (Form) = CTL - ATL
This calculator builds CTL and ATL by running the exponential moving average from zero over the weeks you've held your average weekly TSS, then applies today's session as the final day. Because CTL uses a 42-day window, it takes roughly six weeks at a steady load to converge — so a longer build at the same weekly TSS yields a higher CTL.
Frequently Asked Questions
Chronic Training Load (CTL) represents your fitness level as a rolling average of daily TSS over approximately 42 days. Higher CTL means greater training adaptation.
Acute Training Load (ATL) represents your recent fatigue as a rolling average of daily TSS over approximately 7 days. High ATL means you are accumulating fatigue.
Training Stress Balance (TSB) = CTL - ATL. Positive TSB means you are fresh (rested). Negative TSB means you are fatigued. Ideal race form is typically TSB of +15 to +25.
Recreational: 30-50. Club racer: 60-80. Competitive amateur: 80-110. Professional: 100-150+. Build CTL by no more than 5-7 points per week.
Related Calculators
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Calculate heart rate training zones from max or threshold HR.
Power Zone Calculator
Calculate power-based training zones from your FTP.
TSS Calculator
Calculate Training Stress Score from power and duration.
Training Stress Calculator
Calculate TSS (Training Stress Score) from power, duration, and FTP.
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Last updated: June 2026
All calculations are estimates. Always verify results and consult a professional bike fitter where appropriate.