Training load calculator
rTSS calculator
Enter your pace and duration below to calculate the running training stress score (rTSS) for this run.
rTSS (running Training Stress Score) measures how hard a run was relative to your threshold pace, on the same scale as power-based TSS: 100 equals one hour at threshold.
- Intensity Factor (IF) = threshold pace / average pace
- rTSS = duration in hours × IF² × 100
A 45-minute run at 5:00/km with a threshold pace of 4:30/km gives an IF of 0.90 and an rTSS of 61.
Shape Calendar
Plan runs by load, not by guesswork.
Type “5×1km at threshold” and Shape builds the workout, predicts its load, and syncs it to your Garmin, Apple Watch or Wahoo.