Which method should I use?

Karvonen if you know your resting rate, since it accounts for fitness. Either way the zones inherit the error in your maximum, which is the larger uncertainty.

Why does my zone 2 feel too hard?

Usually because the estimated maximum is too high for you. If easy running puts you in zone 3, the estimate is more likely wrong than your effort.

Health & Fitnessfitness

Heart Rate Zone Calculator

Training zones by the Karvonen and percentage-of-maximum methods. Karvonen uses heart rate reserve, so it accounts for resting rate and gives higher zone boundaries for a fitter person.

Also called: training zone calculator, karvonen formula.

Zone 2, easy aerobic

132 to 144 bpm

Zone 1 120 to 132 bpm, zone 2 132 to 144 bpm, zone 3 144 to 157 bpm, zone 4 157 to 169 bpm, zone 5 169 to 181 bpm. Based on a maximum of 181.4 and a resting rate of 58, giving a reserve of 123.4 beats. Karvonen works from heart rate reserve, so your resting rate shifts every zone boundary.

Zone 1, recovery

120 to 132 bpm

Zone 3, tempo

144 to 157 bpm

Zone 4, threshold

157 to 169 bpm

Zone 5, maximal

169 to 181 bpm

Maximum used

181.4

Heart rate reserve

123.4

On the two methods

Karvonen works from heart rate reserve, so your resting rate shifts every zone boundary.

How this is calculated

For reference only. Verify against your clinical protocol before acting on this number.

Method and background

This is what the calculation gives for the numbers you entered. It is an estimate, not advice, and it knows nothing about your situation beyond those numbers. Rules for United States change on a published schedule; the effective date is shown on every rule-based tool.

How this is calculated

The percentage method takes a share of maximum heart rate directly. Karvonen works from heart rate reserve, the gap between resting and maximum, then adds resting back. The difference is not academic: for someone with a resting rate of 50 the two methods differ by ten beats or more in the middle zones. Since the underlying maximum is itself an estimate with about ten beats of error, zones are a guide rather than a prescription, and effort based on breathing or a talk test is often more reliable.

the Karvonen method works from heart rate reserve, so a fit person with a low resting rate gets different zones

p: Percentage of reserve

Worked examples

Each of these is asserted on every build. If a change to the engine ever moved one of these answers, the build would fail before the page could print it.

Karvonen zones for a 38 year old

Age: 38
Resting heart rate: 58
Maximum heart rate, if measured: 0
Zone method: Karvonen, heart rate reserve

Zone 2, easy aerobic132 to 144 bpm

208 - 0.7 x 38, less a resting 58

Open this example

the percentage method ignores resting rate

Age: 38
Resting heart rate: 58
Maximum heart rate, if measured: 0
Zone method: Percentage of maximum

Zone 2, easy aerobic109 to 127 bpm

boundary: 60 to 70 percent of 181.4

Open this example

Method and limits

What it assumes

Five-zone model. Three-zone and seven-zone models are also in use.

What it deliberately does not model

The maximum is usually an estimate with about ten beats of error, which spans more than a zone.
Heart rate lags effort, drifts upward in heat and rises with dehydration.
Zone models differ between coaching systems, so a zone number is not portable.

Formula version 1.0.0 · definition 1.0.0 · United States · Report a problem with this calculator

Frequently asked questions

Which method should I use?: Karvonen if you know your resting rate, since it accounts for fitness. Either way the zones inherit the error in your maximum, which is the larger uncertainty.
Why does my zone 2 feel too hard?: Usually because the estimated maximum is too high for you. If easy running puts you in zone 3, the estimate is more likely wrong than your effort.