How accurate is "220 minus age"?

It's a widely used population-average estimate, not a precise individual measurement — actual max heart rate can vary by 10-15 beats or more from the estimate for a given age. A supervised max-effort test is more accurate if you need precision.

What zone should I train in most often?

For general cardiovascular fitness, most training volume commonly falls in Zones 2-3 (60-80% HRR), with occasional harder efforts in Zones 4-5 — the ideal balance depends on your specific goals and current fitness level.

When should I measure my resting heart rate?

Immediately after waking, before getting out of bed — this is when it's lowest and most stable, giving the most accurate reading for this calculator.

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Health & Fitness

Heart Rate Zone Calculator

Training zones from your age and resting heart rate.

🔒 Runs entirely in your browser — nothing here is ever uploaded

Last reviewed 2026-08-25

About the Heart Rate Zone Calculator

Calculates your estimated maximum heart rate and five training heart-rate zones using the Karvonen (heart rate reserve) formula, which accounts for your individual fitness level via your resting heart rate rather than using a flat percentage of max heart rate alone.

How to use it

Enter your Age.
Enter your Resting heart rate — measured first thing in the morning, before getting up, for the most accurate reading.
Read your estimated maximum heart rate and five training zones in the result panel.

Formula

Estimated max heart rate = 220 − age
Heart rate reserve (HRR) = max heart rate − resting heart rate
Zone target = (HRR × zone %) + resting heart rate

The Karvonen formula (Martti Karvonen, 1957) is widely considered more personalized than a flat percentage of max heart rate, since it factors in your resting heart rate as a proxy for cardiovascular fitness — two people with the same age and max heart rate but different resting heart rates get different zone targets.

Worked example

At age 35 with a 65 bpm resting heart rate, estimated max heart rate is 185 bpm, and moderate-intensity Zone 3 (70-80% heart rate reserve) falls between about 149 and 161 bpm.

Interpreting your result

"220 minus age" is a widely used estimate, not a precise measurement — actual max heart rate varies meaningfully between individuals of the same age. A supervised max-effort test gives a more accurate number if you need precision for serious training.

Recommendations

• Zone 2 (60-70% HRR) is where most "easy aerobic" or "base-building" training happens — it feels deceptively easy but builds the cardiovascular foundation harder efforts rely on.
• Resting heart rate is most accurate measured immediately after waking, before getting out of bed — it drifts higher later in the day with activity and caffeine.
• A lower resting heart rate over time (all else equal) is a reasonable sign of improving cardiovascular fitness — track it periodically alongside your training.

Frequently asked questions

A flat percentage of max heart rate ignores individual fitness differences. The Karvonen formula's use of heart rate reserve (max minus resting) means two people with the same max heart rate but different fitness levels get different, more personalized zone targets.