Training Load Calculator

What is TSS (Training Stress Score)?

TSS (Training Stress Score) is a metric that quantifies the training load of a single workout by combining duration and intensity. It was developed by Andrew Coggan and Hunter Allen and is used in TrainingPeaks and similar platforms. A 1-hour ride at exactly FTP = 100 TSS. Values above 100 represent very hard efforts; values below 50 are recovery sessions.

What are CTL, ATL, and TSB?

CTL (Chronic Training Load) is your long-term fitness — a rolling 42-day average of daily TSS. ATL (Acute Training Load) is your recent fatigue — a rolling 7-day average. TSB (Training Stress Balance, or 'form') = CTL – ATL. Positive TSB means you are fresh; negative TSB means you are fatigued. Elite athletes often race at TSB of +5 to +25.

How much weekly TSS is sustainable?

This depends heavily on fitness level, recovery capacity, and life stress. Beginners might sustain 200–400 TSS/week; intermediate athletes 400–700; experienced athletes 700–1,000+. A general rule is to increase weekly TSS by no more than 5–10% per week, with an easier recovery week every 3–4 weeks.

What is a good weekly TSS for a beginner?

For a beginner cyclist or runner, 150–300 TSS per week is a solid starting target. This could represent 3–5 hours of moderate training. Prioritise consistency over volume — 200 TSS every week beats 400 TSS one week and 100 the next.

How does TSS compare across different sports?

TSS was originally designed for cycling (power-based). For running, rTSS can be estimated from pace and heart rate. For swimming, similar metrics exist. Cross-sport comparisons are approximate — a 100 TSS bike ride may not create the same fatigue as a 100 TSS run due to differences in muscle damage and impact forces.