How to Calculate Your Heart Rate Training Zones for Running

Heart rate zones tell you how hard you are working relative to your maximum capacity. Training in specific zones produces specific physiological adaptations: Zone 2 builds aerobic base, Zone 4 raises your lactate threshold, Zone 5 improves VO2max. The right zones make structured training work. Zones calculated from inaccurate data make every session feel wrong and undermine the whole purpose of training by effort.

This guide covers how to calculate zones accurately, where the age formula goes wrong, and how to actually apply zones in your training week.

The 5-zone system

Most running coaches and heart rate monitors use a 5-zone system based on percentages of maximum heart rate:

Zone	Name	% of max HR	Effort level
Zone 1	Recovery	50–60%	Very easy, conversational
Zone 2	Aerobic	60–70%	Easy, full sentences
Zone 3	Tempo	70–80%	Comfortably hard
Zone 4	Threshold	80–90%	Hard, short phrases only
Zone 5	VO2max	90–100%	Maximum, unsustainable

Some coaches use 3-zone or 7-zone systems, but the 5-zone model is the most widely adopted and what most Garmin watches display by default.

Method 1: The age formula (simple but imprecise)

The most common starting point is:

Max HR = 220 − age

For a 35-year-old runner, this gives a max HR of 185 bpm. The zone boundaries become:

• Zone 1: 93–111 bpm
• Zone 2: 111–130 bpm
• Zone 3: 130–148 bpm
• Zone 4: 148–167 bpm
• Zone 5: 167–185 bpm

The problem is that the formula has a standard deviation of around 10 to 12 beats per minute. For many people, the calculated max HR is off by 10, 15, or even 20 bpm. If your actual max HR is 170 but the formula gives you 185, your calculated Zone 2 ceiling is 130 bpm instead of the correct 119 bpm. You would be spending your easy runs in Zone 3 and not understanding why you are always tired.

The age formula is a reasonable starting point when you have no other data, but you should verify it before building a training plan around it.

Method 2: Measure your actual max HR

The most accurate zones come from a measured maximum heart rate. Three practical approaches:

Recent race data. Look at your heart rate from a hard 5K race or track session. The peak value is very close to your max HR. Most GPS watches record this in the activity summary under maximum heart rate.

The hill repeat test. After a thorough 15-minute warmup, find a hill and run up it hard for 3 minutes, giving maximum effort in the last 30 to 45 seconds. The highest reading on your device during that final effort is a reliable max HR estimate.

Laboratory VO2max test. The most precise method, requiring specialist equipment. Most runners do not need this level of accuracy, but it is available at sports science facilities and some physiology clinics.

Once you have your max HR, multiply by the zone percentages above and you have accurate zones. Our heart rate zone calculator does this calculation automatically for both the age formula and your measured max HR.

The Karvonen formula

A more sophisticated approach uses heart rate reserve: the difference between your resting heart rate and your maximum heart rate. The idea is that this usable range is more meaningful than raw max HR, because a trained runner with a resting heart rate of 45 bpm effectively has more range available than a sedentary person with the same max HR but a resting rate of 70 bpm.

Target HR = Resting HR + (% intensity × (Max HR − Resting HR))

For a runner with a max HR of 180 and a resting HR of 55:

• Heart rate reserve = 180 − 55 = 125 bpm
• Zone 2 target (65% intensity): 55 + (0.65 × 125) = 136 bpm

This typically produces higher zone targets than the simple percentage method. Many coaches prefer it for trained runners, arguing that it better reflects actual physiological effort at a given percentage of capacity.

Why your zones feel wrong

The most common complaint from runners who start training by heart rate is that Zone 2 is uncomfortably slow. This is almost always correct. True Zone 2 at 60 to 70 percent of actual max HR is slower than most runners expect. It is a comfortable, fully conversational pace where you could hold a proper conversation without any breathlessness.

For many trained runners, this is significantly slower than their normal easy run pace. This is not a flaw in the zone system. It is information about your aerobic fitness. Consistent Zone 2 training over months builds the aerobic base that makes your harder efforts feel easier.

The second common issue is that Zone 4 and Zone 5 appear unreachable. This almost always happens when the age formula has overestimated max HR. If the formula says 185 but your actual max is 170, then your "Zone 5" starts at 167 bpm. You might not reach that number even in a genuinely hard interval session, leaving you confused about whether you are working hard enough.

Both problems are solved by using your actual max HR.

Using zones in your training week

Easy and long runs: Stay in Zone 1 to 2. If your heart rate drifts above Zone 2 on flat terrain, slow down. This is the hardest discipline to maintain because the pace often feels embarrassingly slow at first.

Tempo runs: Zone 3 to 4. A comfortably hard effort you could sustain for around an hour. Classic tempo pace.

Threshold intervals: Upper Zone 4. This is lactate threshold pace, the fastest pace at which your body can clear lactic acid as fast as it is produced. Typically sustained for 10 to 20 minute blocks with short recovery.

VO2max intervals: Zone 5. Short hard efforts of 3 to 8 minutes at maximum sustainable intensity. You should not be able to string more than a few words together.

The 80/20 principle: Decades of research on elite runners consistently shows that around 80 percent of their training volume sits in Zones 1 and 2, with only 20 percent in Zones 3 to 5. Most recreational runners invert this ratio by running easy days too fast. Heart rate monitoring is the most practical way to enforce the easy end of that split.

Heart rate vs pace zones

Both have their place, and most serious runners use both.

Heart rate zones are more accurate for easy runs and hilly terrain, where pace varies with gradient but effort stays constant. Running at 5:30 per kilometre uphill is harder than 5:30 per kilometre on flat ground. Heart rate reflects this automatically.

Pace zones are more precise for structured quality sessions: tempo runs, threshold intervals, and VO2max work. These sessions involve specific physiological targets that are better expressed as pace ranges than heart rate ranges, because heart rate can drift upward during sustained hard efforts (cardiac drift) and responds more slowly to pace changes than you would like in interval work.

The practical approach most coaches recommend: use heart rate for easy runs and long runs, use pace for quality sessions.

Getting started

The most important step is measuring your actual maximum heart rate before building zones from it. A hard parkrun or track 5K effort will give you usable data. Take the highest heart rate recorded during the hard final kilometre, not the average for the whole run.

Then use our free heart rate zone calculator to calculate all five zones from that number. If you also know your resting heart rate (take it first thing in the morning before getting up), you can get Karvonen-adjusted zones at the same time.