Heart Rate Zone Calculator
Most endurance benefit comes from zone 2 — conversational pace. The common error is training everything in zone 3, which is too hard to recover from and too easy to drive much adaptation.
Maximum heart rate
185bpm
- Maximum heart rate
- 185 bpm
- Zone 1 — recovery
- 123–135 bpm
- Zone 2 — endurance
- 135–148 bpm
- Zone 3 — tempo
- 148–160 bpm
- Zone 4 — threshold
- 160–173 bpm
- Zone 5 — maximum
- 173–185 bpm
- Using the Karvonen method, which works from heart-rate reserve — the gap between resting and maximum. It gives higher targets than a plain percentage of maximum and is the better method when you know your resting rate.
- Using the age estimate of 220 less 35, which is 185. It is convenient and it is rough — individual maximums scatter by around twelve beats either side of it, so a tested figure is worth far more.
- Most endurance benefit comes from zone 2 — conversational pace, where you could hold a sentence. The common error is training everything in zone 3, which is too hard to recover from and too easy to drive adaptation.
About heart rate zones
Zones exist to solve one problem: easy sessions get run too hard and hard sessions get run too easy, and the result is a lot of training in the middle that produces less than either. Putting numbers on the intensities makes the discipline possible.
Zone 2 is where most of the volume should sit. It is conversational — you could hold a full sentence — and it feels too easy to be doing anything, which is exactly why people drift out of it. It is where aerobic base is built, and there is no shortcut past it.
How the zones are calculated matters. A plain percentage of maximum treats everyone with the same maximum identically, whatever their fitness. The Karvonen method works from heart-rate reserve — the gap between resting and maximum — which accounts for conditioning and gives noticeably higher targets. On a 185 maximum, zone 2 starts at 111 by the plain method and at 135 by Karvonen with a resting rate of 60.
The 220-minus-age estimate of maximum heart rate is convenient and rough. Individual maximums scatter by around twelve beats either side of it, which is more than a whole zone. If your zones feel consistently wrong, that estimate is the first thing to suspect — a tested figure from a hard effort or a lab test is worth far more.
What it works out
- Five zones from a maximum heart rate
- The Karvonen method when a resting rate is given
- The age estimate of maximum, if you do not know yours
The formula
Karvonen: Target = ((Max − Resting) × Intensity) + Resting
The plain method is simpler and worse: multiply the maximum by the intensity. Sixty per cent of 185 is 111.
Karvonen works from heart-rate reserve — the range your heart actually has available, which is the gap between resting and maximum. For a 185 maximum and a 60 resting rate that reserve is 125 beats. Sixty per cent of it is 75, added back to the resting rate gives 135.
The 24-beat difference is not a rounding detail. It is most of a zone, and the plain method systematically sets targets too low for anyone with a low resting heart rate — which is to say, for anyone fit.
The zones themselves are 50 to 60 per cent for recovery, 60 to 70 for endurance, 70 to 80 for tempo, 80 to 90 for threshold and 90 to 100 for maximum. The boundaries are conventions rather than physiological cliffs, and different systems draw them in slightly different places.
- Max
- Maximum heart rate. Tested beats estimated by a wide margin.
- Resting
- Measured on waking, before getting up. Falls as fitness improves.
- Reserve
- Maximum less resting — the range your heart has to work with.
- Intensity
- The percentage defining each zone boundary.
A worked example
Someone of 35 with a resting heart rate of 60, using the age estimate for maximum.
That works out to 185 bpm.
- Maximum heart rate
- 185 bpm
- Zone 1 — recovery
- 123–135 bpm
- Zone 2 — endurance
- 135–148 bpm
- Zone 3 — tempo
- 148–160 bpm
- Zone 4 — threshold
- 160–173 bpm
- Zone 5 — maximum
- 173–185 bpm
Questions
How do I calculate my heart rate zones?
From your maximum heart rate, as percentages: 50–60% recovery, 60–70% endurance, 70–80% tempo, 80–90% threshold, 90–100% maximum. If you know your resting rate, the Karvonen method uses the reserve between the two and is more accurate.
What is the Karvonen method?
Calculating zones from heart-rate reserve — the gap between resting and maximum — rather than from maximum alone. It accounts for your own conditioning and gives higher targets. On a 185 max with a 60 resting rate, zone 2 starts at 135 rather than 111.
Is 220 minus age accurate?
It is convenient and rough. Individual maximums scatter by around twelve beats either side of it, which is more than a whole zone wide. A tested maximum from a hard effort is much more useful.
What is zone 2 training?
Conversational pace — you could hold a full sentence. It is where aerobic base is built and where most training volume should sit. It feels too easy to be doing anything, which is why people drift out of it.
Why is training in zone 3 a problem?
It is hard enough to need real recovery and not hard enough to drive the adaptations that hard training does. Doing everything there is the classic middle-intensity trap: consistently tired, and improving slowly.
How do I find my resting heart rate?
Measure on waking, before getting up, for several mornings and average them. A wearable tracking overnight will do it for you. It falls as fitness improves, so it is worth rechecking every few months.
How do I find my true maximum?
A supervised lab test is the reliable route. In the field, the highest rate seen during a genuinely maximal effort — repeated hard hill efforts, say — is a reasonable proxy. It is not something to attempt untrained or unsupervised.