Heart Rate Zone Calculator

How the Karvonen method works

The Karvonen formula uses your Heart Rate Reserve (HRR) — the difference between your max and resting heart rate — to calculate training zones:

Target HR = ((Max HR - Resting HR) × % Intensity) + Resting HR

This is more accurate than the simple “percentage of max HR” method because two rowers with the same max HR but different resting rates have very different fitness levels. The Karvonen formula accounts for this by anchoring zones to your personal reserve.

HR zones vs pace zones for rowing

Pace zones (based on your 2K split) and HR zones are complementary, not interchangeable. Pace zones tell you how fast to row; HR zones tell you how hard your body is actually working. They may not always match — fatigue, heat, caffeine, and stress all shift heart rate independent of pace.

The best approach is to use both: aim for a target split, then confirm your effort is in the right HR zone. If your HR is too high for the zone, slow down regardless of what the split says.

Calculate your pace-based zones with our rowing zone calculator and use them alongside these HR zones for the most complete picture.

How to measure your max and resting HR

Resting HR: Measure first thing in the morning before getting out of bed. Use a chest strap or pulse oximeter for accuracy. Average over 3-5 days.

Max HR: The 220-minus-age formula is a rough estimate (standard deviation of ~12 bpm). For a more accurate number, do a max effort test: warm up thoroughly, then row 3 × 1 minute at increasing effort with 1 minute rest, finishing the last interval all-out. Your peak HR in the final interval is close to your true max.