Measure workload with threshold, duration, and intensity inputs. See score, strain, energy, and recovery guidance instantly. Built for athletes tracking smarter sessions across training weeks.
Use direct Normalized Power when available. Otherwise, enter Average Power and Variability Index to estimate it.
Training Stress Score (TSS) is estimated with this formula:
TSS = Duration in Hours × (Intensity Factor)2 × 100
Intensity Factor (IF) = Normalized Power ÷ Functional Threshold Power
Estimated Normalized Power = Average Power × Variability Index when direct Normalized Power is not entered.
Work (kJ) = Average Power × Duration in Seconds ÷ 1000
Session RPE Load = Session RPE × Total Minutes
These formulas help estimate training strain, pacing quality, workload, and recovery needs from one workout session.
| Session | Duration | FTP (W) | NP (W) | IF | TSS | Load |
|---|---|---|---|---|---|---|
| Easy Spin | 01:00:00 | 250 | 150 | 0.60 | 36.00 | Light Load |
| Tempo Ride | 01:30:00 | 250 | 200 | 0.80 | 96.00 | Moderate Load |
| Threshold Session | 01:15:00 | 250 | 238 | 0.952 | 113.29 | Heavy Load |
| Long Endurance Ride | 03:00:00 | 250 | 175 | 0.70 | 147.00 | Heavy Load |
Training Stress Score estimates how demanding one workout was. It combines duration and intensity into a single number, helping athletes compare sessions and plan recovery more consistently.
FTP gives the calculator a personal benchmark. Without it, power data cannot be scaled to your current ability, and the stress score would lose meaning.
You can still use the calculator by entering Average Power and Variability Index. The tool estimates Normalized Power from those values automatically.
Not always. A higher score means more stress, not better fitness by itself. Productive training usually balances load, recovery, and consistency across many sessions.
Yes, but this version is power-based and fits cycling-style training best. Other sports often use pace, heart rate, or session-RPE specific load models.
Intensity Factor shows how hard the session was relative to your threshold. Values near 1.00 indicate work close to threshold intensity.
They add useful context. Power explains external load, while RPE and heart rate show how your body experienced that workload on the day.
Use CSV for training logs, analysis, or spreadsheets. Use PDF when you need a clean report for printing, coaching reviews, or athlete records.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.