Target Heart Rate Calculator — Karvonen (heart rate reserve) method

How it works

There are two ways to turn an intensity into a target heart rate, and this page uses the more precise one. The simple way takes a percentage straight off your maximum — 70% of 190 is 133 bpm. The problem is that it ignores where your heart sits at rest: a very fit person with a resting rate of 45 and an unfit person at 80 get the same target, which can't be right.

The Karvonen, or heart-rate-reserve, method fixes that. Your heart rate reserve is the room between resting and maximum — how much your heart can speed up. The target is your resting rate plus the chosen fraction of that reserve, so it's anchored to your own baseline. Because it starts from resting rather than zero, the Karvonen target sits a bit higher than the plain percentage-of-max at moderate intensities, and the two meet at 100%. This page shows both, and lets you pick 220 − age or Tanaka's formula for the maximum.

Worked example

Mayo Clinic's own example: a 45-year-old with a resting rate of 80 bpm, at 70–85% intensity, using Tanaka's maximum.

• Maximum: 208 − 0.7 × 45 = 176.5 bpm.
• Reserve: 176.5 − 80 = 96.5 bpm.
• 70% target: 80 + 0.7 × 96.5 = 147.55, which the calculator rounds to 148 bpm.
• 85% target: 80 + 0.85 × 96.5 = 162.03, rounding to 162 bpm.

So this person's vigorous zone is about 148 to 162 bpm — the same range Mayo Clinic states for this example. Compare the default case — a 30-year-old, resting 70, at 70% — where Karvonen gives 154 bpm against a plain 70%-of-max figure of 133: the reserve method reads 21 bpm higher because it builds up from the resting rate.

Frequently asked questions

What is the Karvonen method?

A way of setting a target heart rate that accounts for your resting rate. Instead of taking a flat percentage of your maximum, it takes that percentage of your *heart rate reserve* — maximum minus resting — and adds it back to your resting rate. It's widely regarded as more individualised than the plain percentage-of-max approach, especially for fitter people whose resting rate is low.

What's heart rate reserve?

The difference between your maximum heart rate and your resting heart rate — the range your heart has to work within. A 30-year-old with a maximum of 190 and a resting rate of 70 has a reserve of 120 bpm. The bigger your reserve (often a sign of fitness, through a lower resting rate), the more the Karvonen target differs from a plain percentage of maximum.

Why is the Karvonen target higher than the percentage-of-max target?

Because it starts counting from your resting rate, not from zero. At 70% intensity, percentage-of-max gives 70% of your maximum, while Karvonen gives your resting rate plus 70% of the gap above it — which lands higher. The two only coincide at 100% intensity, where both equal your maximum.

How do I find my resting heart rate?

Count your pulse for a full minute first thing in the morning, before getting up, when you're fully at rest. For most adults it's between 60 and 100 bpm; well- trained endurance athletes can be in the 40s. Because the target depends on it, a more careful resting measurement gives a more useful number here.

Which intensity should I train at?

It depends on your goal, and it's worth building up gradually. Broadly, moderate effort (around 50–70%) builds general fitness and is sustainable for longer; vigorous effort (70–85%) improves fitness faster but is harder to hold. The comparison table shows your target across that whole span so you can pick a level and see the bpm it corresponds to.

Does this replace how I feel during exercise?

No. Heart rate is one guide; perceived effort, breathing and the ability to talk are others, and they matter because heart rate is shifted by heat, caffeine, stress, sleep and medication. If your monitor says one thing and your body clearly says another, trust your body and ease off.

Who should be cautious with these numbers?

Anyone with a heart condition, on heart-rate medication such as beta-blockers (which lower both resting and maximum rates and make the age formulas inaccurate), pregnant, or new to exercise should get individualised targets from a clinician. Stop and seek help for chest pain, dizziness or unusual breathlessness whatever the target says.