Target Heart Rate Calculator

How target heart rate is worked out

A target heart rate is a range of beats per minute that corresponds to a given exercise intensity. It starts from your maximum heart rate, the fastest your heart can beat during all-out effort. Measuring that takes a supervised exercise test, so it is usually estimated from age.

The American Heart Association (AHA) describes the target zone as a percentage of maximum heart rate:

• Moderate intensity: about 50% to 70% of maximum.
• Vigorous intensity: about 70% to 85% of maximum.

The CDC’s talk test describes the same two levels without a monitor: during moderate activity you can talk but not sing; during vigorous activity you can say only a few words before pausing for breath.

The AHA suggests aiming for the lower end of the zone in the first weeks of an exercise program and building up gradually. The calculator gives both ranges, the whole 50–85% zone and a table for every 5% step, with the number of beats you would count in 10 or 15 seconds when taking your pulse at the wrist or neck.

Formulas

Two common estimates of maximum heart rate (HRmax):

The second comes from Tanaka, Monahan and Seals (2001), who pooled 351 studies covering 18,712 people and confirmed the equation in a laboratory study of 514 healthy adults. They found it did not differ between men and women or with usual activity level, and that 220 − age underestimates maximum heart rate in older adults. The two formulas agree at age 40; above 40, Tanaka’s gives a higher maximum.

A target heart rate is then a percentage of the maximum:

If you enter a resting heart rate, the calculator also uses the Karvonen (heart rate reserve) method, which applies the percentage only to the beats between resting and maximum:

p

intensity as a fraction: 0.50–0.70 moderate, 0.70–0.85 vigorous

HRrest

resting heart rate in beats per minute

HRmax − HRrest

heart rate reserve

The AHA states its percentages against maximum heart rate. With the Karvonen method the same percentages give higher targets, because the resting rate is added back. Guidelines that prescribe exercise by heart rate reserve use their own percentage bands; this calculator shows the 50–85% band for both methods so you can compare them.

A pulse count converts a target to a short count: beats in 10 seconds = bpm ÷ 6, and beats in 15 seconds = bpm ÷ 4, rounded to the nearest beat.

Worked example

A 40-year-old using 220 − age:

1. Maximum heart rate: 220 − 40 = 180 bpm (Tanaka’s formula gives 208 − 28 = 180 as well).
2. Moderate: 0.50 × 180 = 90 to 0.70 × 180 = 126, so 90–126 bpm.
3. Vigorous: 0.70 × 180 = 126 to 0.85 × 180 = 153, so 126–153 bpm.
4. Pulse check: in 10 seconds, moderate is 15–21 beats (90 ÷ 6 to 126 ÷ 6) and vigorous 21–26 beats (153 ÷ 6 = 25.5, rounded to 26).

With a resting heart rate of 60 bpm, the heart rate reserve is 180 − 60 = 120 beats. The Karvonen moderate range is 60 + 0.50 × 120 = 120 to 60 + 0.70 × 120 = 144 bpm, and vigorous is 144 to 60 + 0.85 × 120 = 162 bpm.

Limits of the estimate

• Everyone differs. Both formulas describe the average for people of an age. Two people of the same age can have maximum heart rates far apart, so a range that feels far too easy or far too hard may simply not fit you. How the effort feels — whether you can still talk — is a useful cross-check.
• Medicines change heart rate. Beta blockers and some other medicines for blood pressure or heart rhythm lower the heart rate reached during exercise. If you take one, an age-based target is not reliable; ask your doctor what to use instead.
• Check before starting hard exercise. If you have a heart condition, chest pain, dizziness, or have been inactive and plan to start vigorous exercise, talk to a doctor first.
• Not for pregnancy, children or medical testing. The formulas were built from adult data and are not a substitute for a supervised exercise test.