Heart Rate Zones Calculator

How runners use this tool

This tool turns age, resting heart rate, and optional max heart rate into practical training zones you can use for easy runs, steady work, tempo, and intervals.

1. Enter age and resting heart rate, then add tested maximum heart rate if you know it.
2. Review the zone table rather than focusing on one number, because training usually works in ranges.
3. Match easy runs, steady runs, tempo work, and interval sessions to the appropriate zone band.

How to use the result

• Treat age-based max heart rate as a starting point and refine the zones with real training data over time.
• Use the lower half of aerobic zones for recovery and long easy days instead of drifting into moderate effort too often.
• If heart rate is unusually high due to heat, fatigue, dehydration, or illness, reduce the session target rather than forcing the planned number.

Formula and assumptions

Karvonen method: target heart rate = resting heart rate + (max heart rate − resting heart rate) × intensity.

• Estimated maximum heart rate can be off by a meaningful margin for individual runners.
• Heart rate lags during short intervals and is influenced by heat, stress, caffeine, and terrain.

Worked examples

• Beginner: Age 35, resting HR 60 → Zone 2 band for easy runs. Stops easy days from drifting too hard.
• Race prep: Known max HR + resting HR → Personalized aerobic/tempo bands. Helps structure race block workouts by intent.
• Advanced: Heat-stressed workout day → Use lower end of target range. Keeps load productive when HR is elevated by conditions.

Common questions