Target Heart Rate Zone Calculator

The Karvonen formula factors in your resting heart rate (via "heart rate reserve" = max HR − resting HR), not just your age, which gives a more personalized target zone than simply taking a flat percentage of your age-predicted max heart rate — two people the same age with very different fitness levels and resting heart rates will get meaningfully different target zones.

This tool uses the widely cited "220 − age" formula, which is a population-average estimate, not a measured value — actual max heart rate varies by as much as ±10-15 bpm between individuals of the same age, so treat these zones as a helpful estimate rather than a precise physiological limit.

Lower zones (50-70% of heart rate reserve) are associated with building an aerobic base and burning a higher percentage of fat as fuel, while higher zones (80-100%) build cardiovascular capacity and speed but are more taxing to recover from — most structured training plans mix zones based on specific goals.

Yes, especially if you have any known heart condition, are new to exercise, or are on medication that affects heart rate (like beta-blockers) — those factors can make the standard formulas inaccurate or unsafe to rely on without medical guidance.