Heart Rate Zones Calculator

What are heart rate training zones?

Heart rate training zones are percentage bands of your maximum heart rate, each targeting a different fitness outcome — from easy recovery work at 50–60% up to all-out VO2 max intervals above 90%. Training by zone keeps easy days easy and hard days hard.

How this calculator works

• Enter your age and resting heart rate — measure resting HR first thing in the morning, before you get up.
• The Karvonen method calculates zones from your heart-rate reserve (max minus resting), which personalises the numbers to your fitness level.
• Switch to max-HR-percentage for the simpler general formula, or enter a measured max HR from a lab or field test.
• Five standard zones are returned, each with a purpose — recovery, endurance, tempo, threshold, and VO2 max.

How to use the result

1. Do most of your weekly mileage in Zone 2 (60–70%). It feels too easy, and that’s the point — it builds aerobic base without frying you.
2. Save Zones 4–5 for 1–2 hard sessions a week. If every run is hard, you aren’t recovering.
3. Use Zone 1 for warm-ups, cool-downs, and the day after a hard session.
4. Recheck resting HR every few weeks — a lower resting rate widens your reserve and shifts the zones.

Karvonen vs. max-HR percentage — which is better?

Karvonen accounts for your resting heart rate, so two people of the same age get different zones based on fitness — it’s the more accurate method for trained athletes. The simple 220 − age formula is fine for beginners. Both are estimates until you measure your true max HR.

Common mistakes

• Using 220 minus age as gospel. It’s an average, not your number; real max HR can be 15+ beats off.
• Training too hard too often. Zone 4–5 every day leads to burnout and injury, not faster times.
• Mixing methods mid-training. Pick Karvonen or max-HR percent and stick with it so your zones stay comparable.

Zones govern how hard you work, but they pair with the nutrition side of training — use the TDEE calculator to set the calories that fuel those sessions, and the macro calculator to balance protein, fat, and carbs around them.