Heart rate zones are intensity bands built from your maximum heart rate. There are two common ways to calculate them — a simple percentage of max, and the more personalized Karvonen method. Both are explained below, with worked examples.
You can skip the math entirely: enter your age in the calculator above and your five heart rate zones are computed instantly.
Step 1: Estimate your maximum heart rate
Use an age formula such as Fox (220 − age), Tanaka (208 − 0.7 × age), or Gulati (206 − 0.88 × age). For a 40-year-old using Fox, that is 220 − 40 = 180 bpm.
Step 2a: Percentage-of-max method
Multiply your max heart rate by each zone's intensity. For Zone 2 at 60–70% of a 180 bpm max: 0.60 × 180 to 0.70 × 180 = 108–126 bpm. Repeat for each zone from 50% up to 100%.
Step 2b: Karvonen (heart rate reserve) method
This method also uses your resting heart rate, so the zones reflect your fitness. The formula is:
Target HR = ((Max HR − Resting HR) × %) + Resting HR
For a 180 bpm max and a 60 bpm resting HR at 60–70%: ((180 − 60) × 0.60) + 60 to ((180 − 60) × 0.70) + 60 = 132–144 bpm — higher than the percentage-of-max result, because it accounts for your resting heart rate.
Frequently asked questions
How do you calculate heart rate zones?
First estimate your maximum heart rate from your age, then take percentage bands of it for each zone — for example 60–70% of max for Zone 2. If you know your resting heart rate, the Karvonen (heart rate reserve) method gives a more personalized result.
What is the Karvonen formula?
The Karvonen, or heart rate reserve, formula is: Target HR = ((Max HR − Resting HR) × intensity %) + Resting HR. Because it factors in your resting heart rate, it adjusts the zones to your individual fitness rather than relying on age alone.
What is heart rate reserve?
Heart rate reserve (HRR) is the difference between your maximum heart rate and your resting heart rate. It represents the range your heart rate can move through during exercise, and it is the basis of the Karvonen method.
Percentage of max or heart rate reserve — which should I use?
Percentage of max heart rate is simplest and needs only your age. Heart rate reserve (Karvonen) is more individualized because it also uses your resting heart rate. If you know your resting HR, prefer the Karvonen method.