Heart Rate Zone Calculator

Heart rate training uses your heart rate (BPM) as a guide to effort instead of pace, which can fluctuate with terrain, wind, or fatigue. Below is exactly how this calculator turns your age and heart rate into five training zones, a worked example you can check by hand, and — because this touches your health — the individual variation and safety notes that matter more here than on a pace or split calculator.

How the Calculation Works

This calculator works in two steps. First, it establishes your max heart rate: if you don't enter one yourself, it defaults to 220 minus your age. Second, it applies the Karvonen formula, which uses your heart rate reserve (HRR) — max heart rate minus resting heart rate — rather than a flat percentage of max heart rate alone:

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

One detail worth knowing: if you leave the resting heart rate field blank, this calculator treats it as 0 bpm rather than estimating one for you. Since the max heart rate field does have a formula default (220 − age) but resting heart rate does not, leaving it blank quietly turns your "Karvonen" zones into simple percentages of max heart rate instead of true heart-rate-reserve zones. For results that actually reflect the Karvonen method, measure your resting pulse — right after waking, before getting out of bed — and enter it.

Worked Example

Enter age 30 with a resting heart rate of 60 bpm and no max heart rate override. Max HR defaults to 220 − 30 = 190 bpm, so heart rate reserve (HRR) = 190 − 60 = 130 bpm. Each zone applies HRR × %Intensity + 60:

• Zone 1 (50–60%): 130 × 0.50 + 60 = 125 bpm to 130 × 0.60 + 60 = 138 bpm
• Zone 2 (60–70%): 138 bpm to 130 × 0.70 + 60 = 151 bpm
• Zone 3 (70–80%): 151 bpm to 130 × 0.80 + 60 = 164 bpm
• Zone 4 (80–90%): 164 bpm to 130 × 0.90 + 60 = 177 bpm
• Zone 5 (90–100%): 177 bpm to 130 × 1.00 + 60 = 190 bpm

Notice every zone boundary lands exactly on 60 (resting heart rate) plus a share of the 130 bpm reserve — that's the Karvonen method in action, and it's why entering a real resting heart rate rather than leaving it blank changes every number in the table above.

Understanding Your Zones

The five zones this calculator generates run from very light recovery effort (Zone 1) up to maximum effort (Zone 5), and different training plans use different zones for different purposes — easy runs and recovery days generally sit in the lower zones, harder threshold and interval work in the upper ones. Heart rate is one useful way to gauge effort, but it responds to more than just running speed — heat, hydration, sleep, caffeine, and stress can all shift your heart rate at a given pace, so it's worth reading alongside, not instead of, how a run actually feels. If you'd rather plan a run around pace than heart rate, our pace calculator and guide to running pace strategy cover that approach, and our piece on heart rate zone training for runners goes deeper into how runners typically use these five zones in a training week.

Limitations & Individual Variation

Every number this calculator produces comes from formulas, not from measuring your actual heart. The 220-minus-age default for max heart rate is a population-average estimate with well-documented individual variation — two people the exact same age can have genuinely different true max heart rates, and other formulas, like Tanaka's 208 − 0.7 × age, produce different estimates for the same age, which is itself a sign of how approximate these numbers are. If you know your real measured max heart rate, entering it directly will give you more personalized zones than the age-based default.

This tool is not medical advice, and it doesn't tell you what intensity to train at or when to push toward your maximum — that's a decision to make with your own body, experience, and, where relevant, medical guidance, not a number on a page. If you have a heart condition, or take medication that affects heart rate (including some common blood pressure medications), talk to a doctor before using formula-based heart rate zones for training, since these formulas were not built with your specific medical situation in mind.

Frequently Asked Questions

How do I calculate my max heart rate?

This calculator estimates it as 220 minus your age if you don't enter your own — for example, at age 30 that's 220 − 30 = 190 bpm. This is a population-average formula, not a measurement, so your true max heart rate could be noticeably higher or lower; a real max heart rate can only be measured directly, typically through a supervised maximal exercise test.

What is the Karvonen formula?

The Karvonen formula calculates a target heart rate using your heart rate reserve (max heart rate minus resting heart rate) instead of a flat percentage of max heart rate alone: Target HR = ((Max HR − Resting HR) × %Intensity) + Resting HR. Because it factors in your resting heart rate, it's generally considered more personalized than percent-of-max-only methods.

How accurate is the 220 minus age formula?

It's a widely used rule of thumb, but individual variation around it is well known to be substantial — two people the same age can have genuinely different real max heart rates. Other formulas exist too; Tanaka's formula (208 − 0.7 × age) produces a different estimate for the same age, which is a good illustration that these are all approximations, not precise measurements of your heart.

What is a good resting heart rate?

Resting heart rate is commonly cited as roughly 60 to 100 bpm for most healthy adults, though it varies by individual, age, medications, and other factors, and a lower resting rate is often associated with cardiovascular fitness. The most reliable way to know your own number is to measure your pulse yourself, right after waking, rather than assume a typical figure.

What happens if I leave resting heart rate blank?

This calculator treats a blank resting heart rate as 0 bpm rather than estimating one for you. That turns your Karvonen zones into simple percentages of max heart rate instead of true heart-rate-reserve zones, which can meaningfully shift the ranges — for the most accurate zones, measure and enter your actual resting heart rate.

What is Zone 2 training and why do people talk about it?

Zone 2 refers to the lower-intensity endurance zone in a 5-zone heart rate model, generally associated with building an aerobic base at a conversational effort. It's a popular topic in running training because many plans include a meaningful share of easy-effort running, though exact zone definitions and recommended proportions vary between coaches and training philosophies.

Is the 220 minus age formula accurate for everyone?

No — it's a population-average estimate, and individual max heart rate can differ from it in either direction for reasons the formula can't capture, including genetics, training history, and other factors. If you know your actual measured max heart rate, entering it directly into this calculator will produce more personalized zones than relying on the age-based default.

Should I use this calculator if I have a heart condition or take medication?

Speak with a doctor before using formula-based heart rate zones for training if you have a heart condition or take medication that affects heart rate — many common medications, including some blood pressure medications, change how your heart rate responds to exercise, which can make age-based formulas and standard zones unreliable or inappropriate for you specifically.