Free Tool

Karvonen Heart Rate Zone Calculator

Calculate training zones using the Karvonen formula (Heart Rate Reserve method). More personalized zones based on your resting heart rate.

About Karvonen (Heart Rate Reserve)

The Karvonen formula, also known as the Heart Rate Reserve (HRR) method, accounts for your resting heart rate to provide more personalized training zones. Developed by Finnish physiologist Martti Karvonen, this method is considered more accurate than simple %Max HR because it factors in your individual fitness level through resting heart rate.

Auto-Calculate from Your Data

Upload Strava, Garmin, or Intervals.icu exports to estimate your zones

Strava vs Garmin vs TrainingPeaks: Zone Differences

Different platforms calculate training zones differently. Here's what each expects:

Strava
Zone System 5-zone (% Max HR)
Algorithm % Max HR
Customizable No

Uses simple % of max HR. Zones are fixed percentages. Cannot customize.

Garmin
Zone System 5-zone (customizable)
Algorithm % Max HR or % HRR
Customizable Yes

Supports both %Max HR and %HRR (Heart Rate Reserve). Fully customizable zones.

TrainingPeaks
Zone System 5 or 7 zone
Algorithm % LTHR (Joe Friel)
Customizable Yes

Uses LTHR-based zones. Supports pace, HR, and power. Highly customizable.

Polar
Zone System 5-zone
Algorithm % Max HR or % HRR
Customizable Yes

Uses either method. Includes sport profiles with different zone settings.