Heart Rate Zone Calculator

Training with heart rate zones helps you match your effort to your goal, whether that is an easy recovery session, steady aerobic fitness building, or a hard interval session. This calculator estimates your maximum heart rate from your age, then breaks it down into five commonly used training zones so you can see roughly what your heart rate should be doing at each intensity.

How to use the heart rate zone calculator

Enter your age to get your estimated maximum heart rate and zones straight away. If you know your resting heart rate, ideally measured first thing in the morning, tick the box to switch to the Karvonen method, which many coaches consider a more personalised estimate since it also accounts for your current fitness level through your resting heart rate.

How the calculation works

Maximum heart rate is estimated using the standard 220 minus age formula. The simple percentage method then multiplies that figure by each zone's percentage range. The Karvonen method instead calculates your heart rate reserve, which is your maximum heart rate minus your resting heart rate, applies the zone percentage to that reserve, then adds your resting heart rate back on. This tends to give slightly higher target zones for the same percentage than the simple method, particularly for people with a low resting heart rate from regular training.

Worked example

For a 35 year old, estimated maximum heart rate is 220 − 35 = 185 bpm. Using the simple percentage method, Zone 2 (60% to 70%) works out as roughly 111 to 130 bpm. If that same person has a resting heart rate of 65 bpm and uses the Karvonen method instead, their heart rate reserve is 185 − 65 = 120 bpm, so Zone 2 becomes (120 × 0.6) + 65 = 137 bpm to (120 × 0.7) + 65 = 149 bpm, noticeably higher than the simple method suggests.

What each zone is generally used for

Zone 1 covers warm-ups and active recovery days, where the aim is to keep effort easy enough to hold a conversation. Zone 2 is widely used for building an aerobic base, often at a pace that still feels comfortable but sustained for longer periods. Zone 3 sits in a moderate, steady effort range often used for tempo work. Zone 4 pushes towards your anaerobic threshold, the point where effort starts to feel noticeably harder and less sustainable, commonly used for interval sessions. Zone 5 represents close to maximal effort, typically held only for short bursts as part of structured interval training.

Common mistakes people make

A common mistake is spending most training time in Zone 4 or 5, chasing a harder workout every session, when a large proportion of easier Zone 1 and Zone 2 training is generally recommended for building a sustainable aerobic base without excessive fatigue. Another mistake is treating the 220 minus age formula as an exact figure rather than a population estimate, when individual maximum heart rate can vary meaningfully from person to person of the same age. It is also easy to forget that factors like heat, dehydration, illness, caffeine and poor sleep can all push your heart rate higher than usual for a given effort, which is not necessarily a sign you are training harder or less fit.

Related calculators

If running is part of your training, our running pace calculator works out your pace and predicts race finish times. For strength training, our one-rep max calculator estimates your maximum lift and a percentage table for programming your sessions. To plan nutrition alongside your training, our TDEE calculator estimates your daily calorie needs, and our calories burned calculator shows the energy cost of individual sessions. For general background on healthy training, see our guide to healthy BMI for UK adults.