How the calculator works
All three methods give you five zones. They differ in the number they are anchored to.
Max heart rate
Each zone is a percentage of your maximum: zone 1 is 50–60%, zone 2 is 60–70%, zone 3 is 70–80%, zone 4 is 80–90% and zone 5 is 90% and up. It is the default on most watches. If you do not know your max, the calculator estimates it as 220 minus your age.
Heart rate reserve (Karvonen)
Your reserve is your max minus your resting heart rate. Each boundary is resting + percentage × reserve, with the same 50–60–70–80–90% steps. Because it starts from your resting heart rate, a fitter athlete with a low resting pulse gets zones that fit them better than a plain percentage of max.
Threshold heart rate (LTHR)
Your threshold heart rate is the highest heart rate you can hold for about an hour. The zones are percentages of it: under 75%, 75–85%, 85–95%, 95–105%, and above 105%. It is the method coaches prefer, because the anchor is a number you measured and it moves as you get fitter.
Heart rate zones by age
Five zones from an estimated max of 220 minus age, in beats per minute. It is a starting point: real maximums vary widely at every age.
| Age | Est. max | Zone 1 | Zone 2 | Zone 3 | Zone 4 | Zone 5 |
|---|---|---|---|---|---|---|
| 20 | 200 | 100–120 | 120–140 | 140–160 | 160–180 | 180 and up |
| 25 | 195 | 98–117 | 117–137 | 137–156 | 156–176 | 176 and up |
| 30 | 190 | 95–114 | 114–133 | 133–152 | 152–171 | 171 and up |
| 35 | 185 | 93–111 | 111–130 | 130–148 | 148–167 | 167 and up |
| 40 | 180 | 90–108 | 108–126 | 126–144 | 144–162 | 162 and up |
| 45 | 175 | 88–105 | 105–122 | 122–140 | 140–158 | 158 and up |
| 50 | 170 | 85–102 | 102–119 | 119–136 | 136–153 | 153 and up |
| 55 | 165 | 83–99 | 99–115 | 115–132 | 132–149 | 149 and up |
| 60 | 160 | 80–96 | 96–112 | 112–128 | 128–144 | 144 and up |
| 65 | 155 | 78–93 | 93–109 | 109–124 | 124–140 | 140 and up |
| 70 | 150 | 75–90 | 90–105 | 105–120 | 120–135 | 135 and up |
Why the zones on your watch look different
Watches do not agree on how many zones there are or what they are anchored to. Garmin and Polar default to five zones from a percentage of max heart rate; Coros uses six. Most let you switch the anchor to heart rate reserve or threshold heart rate, and many adjust your max or threshold automatically after a hard session. If your watch and this page disagree, check which method and which max heart rate the watch is using before you change anything.
Common questions
Which heart rate zone method is the most accurate?
Threshold heart rate is the most accurate of the three, because it is anchored to a number you measured in a hard effort and it moves as your fitness moves. Heart rate reserve comes next: it accounts for your resting heart rate, so two people with the same max get different zones. Percentage of max heart rate is the simplest and the least personal.
Is 220 minus age accurate?
It is an average, not a measurement. For any one person the real maximum is commonly 10 to 20 beats above or below it. Use it to get started, and replace it with the highest heart rate you have actually seen at the end of an all-out effort.
What is zone 2?
Zone 2 is easy aerobic effort: you can speak in full sentences and could keep going for hours. On the five-zone max heart rate model it is 60–70% of max. Most endurance plans put the majority of weekly training time here.
How do I find my threshold heart rate?
Run or ride as hard as you can sustain for 30 minutes, alone, on a flat course. Your average heart rate over the last 20 minutes is a good estimate of your threshold heart rate. Many watches also estimate it for you after a few hard sessions.
How do I find my resting heart rate?
Use the lowest reading your watch records overnight, or count your pulse for a minute just after waking, lying down, on a few mornings and take the lowest.
How does Fit PA use my zones?
Fit PA keeps max heart rate, heart rate reserve and threshold zones on your profile, shows the time you spent in each zone for every activity your watch records, and lets you set the numbers by hand. Your coach reads them when it builds and adjusts your training plan.