Heart Rate Zones: Max Heart Rate, the Karvonen Formula, and a Worked Example
October 21, 2026
Heart rate zones divide exercise intensity into ranges based on how hard your heart is working. Training in the right zone for the goal, whether easy aerobic base building, tempo work, or intervals, helps you get the benefit without overdoing it. The calculation starts with an estimate of your maximum heart rate (HRmax) and then applies percentages, either of the maximum itself or of your heart rate reserve.
The most common formula for HRmax is 220 minus age, which gives 180 beats per minute for a 40-year-old. Other formulas, such as Tanaka's (208 − 0.7 × age), give a similar number at this age: 180. Individual maximums vary by 10 or more beats from the formula, so treat the results as starting points.
Skip the math and get your answer instantly:
Open the Calorie Burn Calculator →Percent of Max Method
Multiply HRmax by the zone percentages. For a max of 180: Zone 1 (50 to 60%) is 90 to 108 bpm, Zone 2 (60 to 70%) is 108 to 126, Zone 3 (70 to 80%) is 126 to 144, Zone 4 (80 to 90%) is 144 to 162, and Zone 5 (90 to 100%) is 162 to 180.
This method is simple, but it ignores fitness level. Two people of the same age can have very different resting heart rates and different ranges of effort.
The Karvonen Method (Heart Rate Reserve)
Heart rate reserve (HRR) is HRmax minus resting heart rate. Target heart rate = resting HR + percentage × HRR. For a 40-year-old with a resting rate of 60: HRR = 180 − 60 = 120. Zone 2 at 60 to 70% of HRR is 60 + 72 = 132 up to 60 + 84 = 144 bpm. Zone 4 at 80 to 90% is 156 to 168.
Because it accounts for resting heart rate, the Karvonen method adjusts for fitness. A fitter person with a resting rate of 50 would have a lower starting point and a slightly different range.
| Zone | % of intensity | Percent of max (bpm) | Karvonen (bpm) | Typical purpose |
|---|---|---|---|---|
| 1 | 50-60% | 90-108 | 120-132 | Recovery, warm-up |
| 2 | 60-70% | 108-126 | 132-144 | Easy aerobic base |
| 3 | 70-80% | 126-144 | 144-156 | Moderate, tempo |
| 4 | 80-90% | 144-162 | 156-168 | Threshold, hard intervals |
| 5 | 90-100% | 162-180 | 168-180 | Max effort, short bursts |
How to Measure Your Resting Heart Rate
Take your pulse first thing in the morning before getting out of bed, for 60 seconds, for several days, and use the average. Typical adult resting heart rates range from 60 to 100 bpm, and well-trained endurance athletes may be below 50. A rising resting heart rate over several days can indicate illness, stress, or overtraining.
Wrist-worn monitors are convenient but can be inaccurate during high-intensity or irregular movement. Chest straps generally track heart rate during exercise more reliably.
Using the Zones
Much of endurance training is done in Zone 2, a pace at which you can hold a conversation. It builds aerobic capacity with moderate fatigue. Harder sessions in Zones 4 and 5 improve speed and VO₂max but need recovery. Many programs follow an 80/20 pattern, with about 80% of sessions easy and 20% hard.
Heart rate lags the effort and is affected by heat, hydration, caffeine, sleep, and altitude. Use perceived exertion alongside it: Zone 2 should feel easy, and Zone 4 should feel hard but controlled.
Limits of the Formulas
The 220 − age formula was derived from limited data and has a standard deviation of about 10 to 12 bpm. If you regularly see a heart rate above your calculated maximum, your real maximum is higher, and you should recalculate your zones from observed data. A supervised test or an all-out effort at the end of a hard session can give a better value, but should be done only if you are healthy and have cleared it with a doctor. Medications such as beta blockers lower the heart rate and alter the zones.
Frequently Asked Questions
How do I calculate my maximum heart rate?
A common estimate is 220 minus your age. Tanaka's formula, 208 − 0.7 × age, is another.
What is the Karvonen formula?
Target heart rate = resting heart rate + intensity percentage × (max heart rate − resting heart rate).
Which zone burns the most fat?
Lower zones use a higher share of fat, but higher zones burn more total calories. Overall energy balance matters more.
What heart rate is Zone 2 for a 40-year-old?
About 108 to 126 bpm by percent of max, or 132 to 144 by the Karvonen method with a resting rate of 60.
Are wrist heart rate monitors accurate?
They are good at rest and steady efforts but can be less reliable during intervals or when the strap shifts.