TSS calculator

Training Stress Score puts a number on how much a ride took out of you, by combining how hard with how long. The anchor is simple: one hour at exactly your FTP is 100 TSS. Everything else is measured against that.

This is what lets a gentle three-hour ride and a savage forty-minute session sit on the same scale. Without it you are comparing a distance to a feeling, and neither tells you whether tomorrow should be hard or easy.

IF is the ride's power divided by your FTP. An hour at IF 1.0 is flat-out threshold work; IF 0.65 is conversational endurance. Rough guide:

Use normalised power if your head unit gives it. On a steady indoor workout, average power is close enough that the difference will not change any decision you make.

There is no correct number, only a correct direction: this week should not be dramatically bigger than the last few. A rough map for riders training indoors around a job:

• 200–300 a week — three or four sessions, building steadily. Where most people should be.
• 300–450 — five sessions including a long one. Needs the sleep to back it up.
• Above 450 — possible, but not on a rotating roster, and not for long.

On my own plan a normal week lands between 250 and 380, and a week with night shifts drops to about 150 — almost all of it easy. That drop is not failure. It is the reason the plan is still running.

It cannot see your sleep, your job, or the fact that you are coming down with something. Two identical 280 TSS weeks can leave you fresh or wrecked. That is why every session on this site gets a 1–5 rating written next to it afterwards: the score says what the session cost on paper, the rating says what it cost you.