Neverpedia
Training load
IF (Intensity Factor)
A workout's Normalized Power divided by your FTP — a simple measure of how hard the ride was relative to threshold.
Intensity Factor (IF) is the ratio of a ride's Normalized Power (NP) to your FTP. It is a number, usually between 0.4 and 1.1, that tells you how hard the ride was relative to your threshold.
How it is calculated
IF = NP / FTP
So an NP of 220W with a 250W FTP gives an IF of 0.88 — a sweet spot or tempo ride.
Why it matters
IF is intuitive. You do not need to know the watts to know what the ride was — just the IF.
- IF < 0.65 — recovery
- 0.65–0.75 — endurance
- 0.75–0.85 — tempo
- 0.85–0.95 — sweet spot / sub-threshold
- 0.95–1.05 — threshold
- 1.05+ — VO2 / anaerobic
IF also pairs with duration to estimate TSS — a 2-hour ride at IF 0.85 will produce roughly 145 TSS.
Common misconceptions
- IF above 1.0 for an hour is possible only if your FTP is wrong (or you had an exceptional day).
- IF is calculated from NP, not average power — short, hard ride sections push it up more than steady riding does.
Related concepts
NP, FTP, TSS.