A heart rate target turns “exercise at a moderate intensity” into a number you can check on a watch or with your fingers on your wrist. This calculator estimates your maximum heart rate, then builds a target range and five training zones using either the Karvonen heart-rate-reserve method or a simple percentage of maximum.
How to use the target heart rate calculator
- Enter your age.
- Choose how to estimate maximum heart rate: the classic 220 − age, the Tanaka or Gulati formulas, or a maximum you have measured in a supervised test.
- Pick a method. Karvonen also needs your resting heart rate.
- Set the lower and upper intensity. The default 50–85% spans moderate to vigorous exercise.
- Read your target range on the tape and the zone table below it.
Target heart rate formulas
First, estimate maximum heart rate (MHR):
The Karvonen method works with heart rate reserve (HRR), the difference between maximum and resting rates:
The percent-of-maximum method simply multiplies: Target = MHR × intensity.
Worked example
A 40-year-old with a resting heart rate of 70 bpm, using 220 − age:
MHR = 220 − 40 = 180 bpm; HRR = 180 − 70 = 110 bpm
50%: 110 × 0.50 + 70 = 125 bpm · 85%: 110 × 0.85 + 70 = 163.5 ≈ 164 bpm
During exercise, a 10-second pulse count of about 21 to 27 beats puts this person in range.
With percent of maximum instead, the same 50–85% range is 90–153 bpm. The difference is the resting rate: Karvonen assumes the first 70 beats are “free” and scales only the reserve above them.
Heart rate training zones
Coaches often split effort into five zones. The table under your result converts them to beats per minute.
| Zone | Intensity | What it feels like |
|---|---|---|
| 1 — very light | 50–60% | Easy conversation; warm-ups and recovery |
| 2 — light | 60–70% | Comfortable, steady breathing; long, easy sessions |
| 3 — moderate | 70–80% | Speaking in short sentences; aerobic endurance |
| 4 — hard | 80–90% | A few words at a time; tempo and threshold efforts |
| 5 — maximum | 90–100% | Unsustainable for more than a minute or two |
For Karvonen-based guidance, the American College of Sports Medicine describes moderate intensity as about 40–59% of heart rate reserve and vigorous as 60–89%, which the result also lists.
Which maximum heart rate formula should you use?
The 220 − age rule became popular in the early 1970s as a convenient approximation, not as the output of a careful study. In 2001 Hirofumi Tanaka and colleagues pooled 351 studies covering more than 18,000 adults and found 208 − 0.7 × age fit better, particularly for older people. Martha Gulati’s 2010 analysis of about 5,400 women produced 206 − 0.88 × age. Even the better formulas only describe averages: any individual’s true maximum can sit 10 or more beats above or below the estimate, which shifts every zone. A measured maximum from a supervised exercise test removes that uncertainty.
Checking your heart rate
Chest-strap monitors are the most accurate everyday option; wrist-based optical sensors are convenient but can lag during intervals. Without a device, count your pulse for 10 seconds and multiply by six. If numbers and feel disagree, trust the talk test: during moderate exercise you can talk but not sing.
For pacing runs once you know your zones, see the running pace calculator.
This calculator is informational only and is not medical advice. If you have heart disease, high blood pressure, take medication that affects heart rate, or are starting a new exercise program after being inactive, consult a healthcare professional first.
Frequently asked questions
What is a good target heart rate during exercise?
The American Heart Association describes moderate exercise as about 50–70% of maximum heart rate and vigorous exercise as about 70–85%. For a 40-year-old with an estimated maximum of 180 bpm, that is roughly 90–126 bpm for moderate and 126–153 bpm for vigorous effort.
What is the Karvonen formula?
It sets targets as a percentage of heart rate reserve — the gap between maximum and resting heart rate — and then adds the resting rate back: target = (max − resting) × intensity + resting. Because it accounts for fitness through the resting pulse, it gives higher targets than percent of maximum at the same intensity.
Why is 220 minus age considered inaccurate?
The 220 − age rule was never derived from a rigorous study, and real maximum heart rates scatter widely around it — a standard deviation of roughly 10 to 12 bpm. The Tanaka formula, 208 − 0.7 × age, fits large data sets better, especially after age 40, and Gulati's formula was developed specifically for women.
How do I measure my resting heart rate?
Right after waking, before getting out of bed or having caffeine, count your pulse at the wrist or neck for a full 60 seconds. Repeat on three or four mornings and average the results.
Can I use these zones if I take heart medication?
Beta blockers and several other drugs slow the heart and limit how high it can climb, so formula-based zones may be far too high. In that case, ask your clinician how to judge effort; perceived exertion or the talk test may work better.