Training Load Calculator

How to Use This Calculator

1. Enter your workout duration, intensity (% of FTP), and FTP to get TSS instantly.
2. Use Cycling TSS tab if you have Normalized Power from your power meter.
3. Use Running TSS (TRIMP) tab with heart rate data for run workouts.
4. Use Weekly Load tab to enter daily TSS values and see total weekly load.
5. Professional tier: enter your CTL, ATL, and today's TSS to compute TSB (form) and projected CTL/ATL after the workout.

Formula

Example

Frequently Asked Questions

• What is TSS (Training Stress Score) and how does it work? ▼
  TSS (Training Stress Score) is a single number that quantifies the training stress of a workout, accounting for both duration and intensity. It was developed by Andrew Coggan and popularized by TrainingPeaks and the book 'Training and Racing with a Power Meter.' For cycling, the formula is: TSS = (duration_seconds × NP × IF) / (FTP × 3600) × 100, where NP is Normalized Power (watts), IF is Intensity Factor (NP/FTP), and FTP is Functional Threshold Power. The normalization ensures that one hour at exactly FTP (IF = 1.0) always equals exactly 100 TSS. Easier workouts produce fewer TSS: 2 hours at 65% of FTP (Zone 2 endurance) ≈ 85 TSS, while 1 hour of threshold intervals at 95% FTP ≈ 90 TSS. The power of TSS is that it creates a single currency of training load comparable across all workout types. When accumulated over days, weeks, and months, TSS values feed the CTL (fitness), ATL (fatigue), and TSB (form) model — the quantitative framework that underlies performance management in endurance sports.
• How much TSS per week is appropriate for my fitness level? ▼
  Weekly TSS targets vary significantly by fitness level, training phase, and sport. Beginner cyclists and runners typically accumulate 100-250 TSS per week during early training — enough to build aerobic fitness without overwhelming recovery capacity. Recreational athletes training 6-10 hours per week at moderate intensity might accumulate 300-500 TSS per week. Competitive amateur athletes putting in 10-15 hours per week typically see 500-800 TSS per week during build phases. Serious amateurs and masters athletes training 15-20 hours per week might accumulate 700-1000 TSS per week. Professional cyclists in stage races can accumulate 500-1000 TSS in a single day during mountain stages, and 3000-5000 TSS over a three-week grand tour. The important metric is not the absolute weekly TSS but the rate of change — how quickly you are increasing TSS week over week. The safe ramp rate is approximately 5-8 TSS per day per week (35-56 TSS per week of increase). Increasing faster is a common cause of overuse injuries, immune suppression, and overtraining syndrome.
• What is the difference between acute and chronic training load? ▼
  Chronic Training Load (CTL) and Acute Training Load (ATL) represent two different time horizons of training stress, using exponentially weighted moving averages of daily TSS. CTL uses a 42-day time constant, meaning today's workout contributes about 2.3% of its TSS to CTL while yesterday's contributes slightly more — the effect gradually decays. CTL is your fitness measure: it reflects the cumulative training stress you have absorbed and adapted to over the past several weeks and months. A high CTL means high fitness. ATL uses a 7-day time constant, decaying much faster. ATL is your fatigue measure: it reflects the recent training stress you have not yet fully recovered from. After a hard week of training, ATL rises faster than CTL because the recent stress dominates. After a recovery week, ATL drops quickly (7-day decay) while CTL only decreases slowly (42-day decay). The difference CTL − ATL is TSB (Training Stress Balance), or form: when you are fresh relative to your fitness, TSB is positive. The key insight of the PMC (Performance Management Chart) model is that fitness (CTL) must be built through accumulated fatigue (ATL > CTL), and peak performance requires a taper phase where ATL drops while CTL remains elevated.
• Why is 'ramp rate' important and how do I avoid overtraining? ▼
  Ramp rate is the week-over-week rate of increase in CTL — how quickly you are building fitness. The standard safe guideline is a ramp rate of 5-8 CTL points per week (roughly equivalent to adding 35-56 TSS per week). Going faster increases injury risk, suppresses the immune system, and can lead to overreaching or overtraining syndrome. The physiological reason: adaptation to training stress requires recovery time. Tendons, ligaments, and bone (which cause most overuse injuries) adapt more slowly than the cardiovascular system — your heart can handle more training before tendons are fully recovered. So it is possible to feel cardiovascularly ready for more training while connective tissues are still adapting. By limiting ramp rate, you ensure all systems adapt together. Practical signs of excessive ramp rate: persistent fatigue beyond 48 hours after hard workouts, elevated resting heart rate (>5-7 bpm above normal), declining performance in workouts that should feel manageable, increased illness frequency, mood disturbances, and sleep disruption. Recovery from overtraining can take weeks to months — it is far more costly than the fitness lost from a conservative build.
• How can I use TSB (Training Stress Balance) to peak for a race? ▼
  TSB (Training Stress Balance = CTL − ATL) is your form indicator, and managing it around key races is the central skill of periodization. Fresh is not always fast: TSB must be positive but not too positive. Research and coaching experience suggest that optimal TSB for peak performance is typically between +5 and +25 for most athletes. Too negative (below −25): you are too fatigued to perform well even though fitness (CTL) may be high. Too positive (above +30): you have lost too much fitness through under-training; fitness (CTL) has declined. The tapering process involves reducing training volume (and therefore ATL) in the 1-3 weeks before a key event while maintaining intensity to preserve fitness (CTL declines slowly over 42 days). A typical taper reduces volume 40-60% while keeping 1-2 high-intensity sessions per week. For a target TSB of +15 on race day with current CTL 70, ATL 85, TSB −15: you need 2-3 weeks of reduced training for ATL to drop to approximately 55 (CTL 70 − ATL 55 = TSB +15). Elite athletes and their coaches track CTL, ATL, and TSB daily in TrainingPeaks or WKO to choreograph the exact taper needed for their A-race.

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