Target Heart Rate Calculator

Two ways to estimate your target heart rate

Ask three fitness sites for your target heart rate and you may get three different numbers, because there are two ways to work it out and they do not agree.

The first is the percentage of maximum method, which is what most charts use. You estimate your maximum heart rate and take a slice of it. The American Heart Association publishes its zone chart this way, putting moderate activity at 50% to 70% of maximum and vigorous activity at 70% to 85%.

The second is the Karvonen method, named after the Finnish researcher who published it in 1957. It works with your heart rate reserve, which is the gap between your maximum and your resting pulse, and then adds your resting rate back at the end:

• Percentage of maximum: target = percentage x maximum heart rate
• Karvonen: target = resting heart rate + percentage x (maximum heart rate - resting heart rate)

The difference between them is not academic. On the worked example below, the two methods land 21 beats per minute apart at the same intensity, which is the difference between an easy walk and a run.

Maximum heart rate, 220 minus age and the alternatives

Both methods start with an estimated maximum, so it helps to know where that estimate comes from.

The classic figure is 220 minus your age. It came out of a 1971 review of a handful of studies, and it was never fitted as a regression line. It survived because it is easy to do in your head, not because it is precise. For any individual the estimate is usually off by 10 to 20 beats per minute, and the error grows at the extremes of age.

A 2001 analysis by Tanaka and colleagues pooled 351 studies covering more than 18,000 people and produced a different line: 208 minus 0.7 times your age. It tends to run a little lower for young adults and a little higher for older adults, and the two lines cross at about age 40, where both give 180 for a 40 year old.

Do not treat either number as measured. If you have ever seen your own heart rate at the end of a hard effort, that observed number beats any formula, and the calculator above lets you compare what each formula says.

Heart rate reserve and the Karvonen formula

Your heart rate reserve is the number of beats you have to work with. It is your maximum minus your resting rate, and the Karvonen method spends a percentage of that reserve rather than a percentage of the whole scale.

The logic is that the first beats above resting are the cheap ones. Someone whose heart sits at 50 beats per minute at rest has 130 beats of room to run at a maximum of 180, while someone resting at 70 has only 110. Spending 70% of a bigger reserve is a bigger ask than spending 70% of a smaller one.

Here is what that does in practice. Two people are both 40 years old with the same estimated maximum of 180. One rests at 70, the other at 52.

• Resting 70. Reserve is 110, so 70% of reserve plus resting is 147 bpm.
• Resting 52. Reserve is 128, so 70% of reserve plus resting is 142 bpm.

Under the plain percentage method both people get 126 bpm, because their ages match and that method ignores everything else. Under Karvonen they get different zones, which is the entire argument for using it. The reserve method is the standard in cardiac rehabilitation programs, where the difference matters.

Worked example: age 40 with a resting pulse of 70

Here is the case loaded into the calculator above, taken step by step. The person is 40 years old with a resting pulse of 70 beats per minute.

• Estimated maximum. 220 minus 40 is 180 bpm.
• Heart rate reserve. 180 minus 70 is 110 bpm.
• Moderate zone, 50% to 70%. 70 plus 55 is 125, and 70 plus 77 is 147, so the zone is 125 to 147 bpm.
• Vigorous zone, 70% to 85%. 70 plus 77 is 147, and 70 plus 93.5 is 164, so the zone is 147 to 164 bpm.

Now run the same person through the percentage of maximum method. Fifty percent of 180 is 90 and seventy percent is 126, giving a moderate zone of 90 to 126 bpm. Eighty five percent is 153.

The two moderate zones do not overlap. The reserve method says 125 to 147 and the simple method says 90 to 126, and the only beat they share is around 125. If you train at 126 because a chart told you to, the reserve method says you are just starting to work.

The gap between them is 21 beats per minute at 70% intensity, and it is not a coincidence. The difference works out to 30% of your resting heart rate at that intensity, so a resting pulse of 70 produces a 21 beat gap, and a resting pulse of 60 produces an 18 beat gap.

The five training zones in beats per minute

Most training plans divide the range into five zones. The usual cut points are expressed as a percentage of heart rate reserve, and the table below converts them into beats for our 40 year old with a resting pulse of 70.

Two things about zones catch people out. The first is that the zone boundaries are estimates on top of an estimate, so treat them as a dial rather than a switch. The second is that zone 2 is where most of the training volume belongs, and most people who think they are training in zone 2 are in zone 3, because they are going harder than the breathing test allows.

How much the two methods disagree by age

How much do the choices matter? Enough to change a training plan, and the differences are largest where you would not expect them.

The gap column is flat at 21 beats, and that is the cleanest way to understand the two methods. At 70% intensity the reserve method always sits 30% of your resting pulse above the simple method, whatever your age. The choice of maximum formula moves the number by less: the classic and Tanaka lines agree exactly at 40 and differ by 9 beats at age 70.

So the method you pick matters more than the formula you pick. If you are going to use one number, use the reserve method with a resting pulse you measured yourself, because it uses two real facts about you instead of one.

Medicines and conditions that change your heart rate

Heart rate zones assume a normal heart responding to exercise in a normal way. A long list of ordinary medicines and conditions breaks that assumption, and the list is longer than most people expect.

If you take a beta blocker, the most common situation here, the standard formulas will tell you to work harder than you should, because your real maximum is lower than the formula thinks. Some cardiology clinics run a graded exercise test and give you a personal target instead. That number beats anything this page can produce.

Stop and get help if exercise brings chest pain, dizziness, unusual shortness of breath or a heart rate that will not come back down. This page is an educational estimate, not medical advice, and it does not replace a conversation with your own doctor.

How to measure your pulse and use the zones

The number is only as good as the two inputs you feed it, and both are easy to measure at home.

Resting heart rate. Take it first thing in the morning, before coffee and before you get out of bed. Sit or lie quietly for five minutes, then count your pulse for 60 seconds, or count for 30 seconds and double it. Do it three mornings in a row and use the lowest, because one bad night of sleep will lift the reading. A typical adult rests between 60 and 80 beats per minute, and trained endurance athletes often sit in the 40s or 50s.

Heart rate during exercise. Counting by hand is awkward in motion, so either stop and count for 10 seconds then multiply by six, or use a chest strap or an optical watch. Chest straps track changes faster, which matters for intervals.

The talk test. It is free and it needs no equipment. At moderate intensity you can talk in full sentences but not sing. At vigorous intensity you can say only a few words at a time. The talk test lands close to the zones for most people, and it still works if you take a medicine that blunts heart rate.

The American Heart Association target heart rate chart gives the simple method's zones by age, and the CDC adult activity guidelines set the weekly target at 150 minutes of moderate activity or 75 minutes of vigorous activity, plus two sessions of muscle strengthening. Use the calculator to find the beats, then use the talk test to check them.