HesapHanem

Training Stress Score (TSS) Calculator

Compute a ride’s Training Stress Score.

How it is calculated

The engine first computes IF = NP ÷ FTP, then TSS = (minutes × IF² × 100) ÷ 60. Duration is in minutes, and normalized power and FTP are in watts. Because IF is squared, effort counts much more than time: doubling intensity quadruples the score for the same duration. A ride of 60 minutes exactly at FTP gives 100. TSS is rounded to a whole number and the intensity factor is shown with two decimals; the unrounded IF is used inside the formula. Duration and FTP must be above zero and NP cannot be negative, otherwise the tool returns nothing. It scores one ride and does not add up days or weeks of training.

Worked example

A rider with an FTP of 250 W does a 90-minute ride with a normalized power of 215 W. Intensity factor: 215 ÷ 250 = 0.86. Squared: 0.86 × 0.86 = 0.7396. Then 90 × 0.7396 × 100 ÷ 60 = 110.9. The calculator shows a TSS of 111 and an intensity factor of 0.86. A single hour at exactly 250 W would score 100, so this longer, slightly easier ride counts as a little more load than that benchmark.

Try this example →

Common mistakes

  • Entering the duration in hours (1.5) instead of minutes (90). The score then comes out 60 times too low, here about 2.
  • Using average power instead of normalized power. For rides with many surges, average power is lower and understates the load.
  • Using an out-of-date FTP. A too-low FTP inflates IF and TSS; a too-high one deflates them.
  • Comparing TSS across riders with different FTP definitions. A 20-minute test result used directly as FTP is not the same figure as a 60-minute value.

Sources

About this calculator

Training Stress Score (TSS) is a proprietary metric created by Dr. Andrew Coggan and popularized through TrainingPeaks and power-meter-based cycling coaching, designed to quantify the overall physiological stress of a single ride in one number. It combines duration, Normalized Power (NP) — a weighted-average power output that accounts for the variability of real-world riding better than a simple average — and your FTP (Functional Threshold Power), the highest power you can sustain for roughly an hour. In the units this calculator uses, the formula is TSS = (minutes × IF² × 100) / 60, where IF (Intensity Factor) is derived as NP divided by FTP — so ride minutes, NP and FTP are the only inputs needed.

Cyclists, triathletes, and their coaches use TSS as the core building block of periodized training plans: a 1-hour ride at exactly FTP scores 100 TSS by definition, giving athletes a consistent yardstick to compare a short hard interval session against a long easy endurance ride. TSS feeds directly into longer-term load-management metrics like CTL (Chronic Training Load, or ‘fitness’) and ATL (Acute Training Load, or ‘fatigue’), which coaches track to manage the balance between building fitness and avoiding overtraining or injury.

Was this helpful?

You can pick up to 3 reactions.

Comments

  • Be the first to comment.

Popular calculators

Loan Calculator

Monthly payment, total interest and full amortization schedule.

Percentage Calculator

Percent change, percent of, and ratio calculations.

Discount Calculator

Calculate final price, savings, and discount amount.

BMI Calculator

Body mass index from height and weight (metric or imperial).

Age Calculator

Compute your exact age in years, months and days from a birth date.

Compound Interest Calculator

Calculate the final amount and interest earned with compounding.

All Calculators