What is Normalised Power?

Normalised Power accounts for the variability of your effort. A ride with surges and recoveries has a higher metabolic cost than steady riding at the same average power.

What is Variability Index?

VI = Normalised Power / Average Power. A VI of 1.0 means perfectly steady. Criteriums may have VI of 1.3+. Road races typically 1.05-1.15.

What is Intensity Factor?

IF = NP / FTP. An IF of 1.0 means you rode at your threshold. IF above 1.05 is unsustainable for long durations.

How is TSS calculated?

TSS = (duration_seconds x NP x IF) / (FTP x 3600) x 100. A 1-hour ride at FTP gives a TSS of 100.

BikeCalcs

Normalised Power Calculator — NP from Average Power

Calculate normalised power from average power and variability index.

Average Power

Variability Index

Steady ride ~1.03, Variable ~1.10+

FTP

Duration

How We Calculate This

Normalised Power Formulas

NP = Average Power x Variability Index
Intensity Factor (IF) = NP / FTP
TSS = (seconds x NP x IF) / (FTP x 3600) x 100

Note: True NP is calculated from 30-second rolling averages of power data. This calculator provides an estimate from average power and VI.

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates. Always verify results and consult a professional bike fitter where appropriate.