NumberTally Target Heart Rate Calculator
Find your training zones with the Karvonen formula. Enter your age and resting heart rate to see all five intensity zones — or switch to the Tanaka max-heart-rate formula in Advanced options and compare both.
Measure first thing in the morning, before getting up.
Advanced options
Tanaka fits measured data better, especially past age 40. Compare both in the box below.
What the Karvonen formula does
Karvonen personalizes intensity using your heart rate reserve (HRR) — the gap between your max and resting heart rates. Target = (HRmax − RHR) × intensity + RHR. Two people with the same max but different resting rates get different targets, which is the point: a lower resting rate means a bigger reserve and higher training targets at the same percentage.
The classic 220 − age estimate is simple but crude; the Tanaka formula (208 − 0.7 × age) tracks lab-measured maximums more closely, particularly for older adults. For a 30-year-old the difference is small (190 vs 187), but it widens with age.
What each zone feels like
Recovery (50%) feels easy — you could hold a full conversation. Fat burn (60%) is a brisk effort where fat contributes a larger share of fuel. Cardio (70%) is the classic aerobic zone: breathing hard but sustainable. Peak (80%) is uncomfortable — short sentences only. Red line (90%+) is an all-out effort you can hold for a minute or two. Most weekly training belongs in the first three zones.
Frequently Asked Questions
How do I measure my resting heart rate?
Take it first thing in the morning before getting out of bed, ideally averaged over 3–5 days. Count beats for 60 seconds with fingers on your wrist or neck — or read it off a wearable's morning report. Caffeine, stress, and illness all raise it temporarily.
Is 220 minus age accurate?
It's a population average with a typical error of ±10–12 bpm for individuals. The Tanaka formula (208 − 0.7 × age) fits measured maximums better on average. For the most accurate zones, use a lab-measured or field-tested max instead of any formula — switch formulas in Advanced options to see how much it matters for you.
What is heart rate reserve?
Your max heart rate minus your resting heart rate — the full range your heart can work across. Karvonen scales intensity within this reserve rather than as a flat percentage of max, which personalizes the zones to your fitness level.
Which zone burns the most fat?
The "fat burn" label on the 60% zone refers to the share of calories from fat, which is highest at lower intensities — but total calories burned per minute rises with intensity. For fat loss, total energy expenditure and diet matter far more than which zone you train in.
Is it dangerous to exceed my max heart rate?
Formula-based maximums are estimates, so briefly exceeding the number is common and usually harmless in healthy people. But chest pain, dizziness, or unusual shortness of breath are stop signals — talk to a healthcare professional before hard training if you have any heart concerns.
Estimates only — not medical advice. Consult a healthcare professional before intense exercise.