Estimate workout load from duration, normalized power, and FTP using the standard Training Stress Score model.
min
W
W
Training Stress Score
116TSS
Intensity Factor
0.88IF
IF = normalized power ÷ FTP. TSS = duration in hours × IF² × 100.
About Cycling TSS Calculator
Estimate cycling Intensity Factor and Training Stress Score using workout duration, normalized power, and functional threshold power. Useful for checking the load of a planned or completed ride.
Calculate cycling training load from duration and relative intensity
The calculator uses workout duration, Normalized Power, and current FTP to show Intensity Factor and an estimated Training Stress Score. It is most useful for auditing one planned or completed ride against the same athlete's current threshold.
Use Normalized Power—not average power
Intensity Factor is Normalized Power divided by FTP. TSS is duration in hours multiplied by Intensity Factor squared and by 100. At NP equal to FTP, one hour therefore equals 100 TSS by definition.
Normalized Power accounts for variable effort through a separate algorithm. This calculator does not derive NP from raw power data, so copy the value from a compatible head unit or analysis platform rather than substituting average power without acknowledging the difference.
Keep FTP current
The score is highly sensitive to FTP because relative intensity is squared. An FTP set too low inflates IF and TSS; an FTP set too high suppresses both. Compare rides only after checking which FTP value and NP method were used.
Recalculate after a meaningful FTP update.
Use the same data platform when consistency matters.
Treat planned TSS as a load estimate, not a promise of a particular recovery time.
Connect load to the training decision
TSS compresses duration and relative intensity into one number; it does not describe interval structure, heat, fueling, technical stress, sleep, or individual response. Use it alongside the workout's purpose, recent load, and how the athlete actually recovered.
Frequently asked questions
Why does one hour at FTP equal 100 TSS?
At NP equal to FTP, Intensity Factor is 1.0. The formula becomes 1 hour × 1² × 100, which equals 100.
Can I enter average power instead of Normalized Power?
You can calculate a rough scenario, but it is not the stated TSS model for a variable ride. Average power may underrepresent the cost of repeated surges.
Is TSS a recovery prescription?
No. It estimates training load from duration and relative power. Recovery also depends on the athlete, workout structure, environment, nutrition, sleep, and accumulated fatigue.