What this calculator does
Training zones divide the range between your resting and maximum heart rate into bands, each associated with different physiological adaptations. Low zones build aerobic base and aid recovery; high zones develop threshold and peak capacity.
This calculator uses the Karvonen method, which works from heart rate reserve, the gap between resting and maximum, rather than a plain percentage of maximum. It produces more individualised zones, because it accounts for the fact that a well-conditioned athlete with a low resting heart rate has a wider working range.
The formula
Maximum heart rate is estimated with the Tanaka equation, 208 − 0.7 × age, which fits population data better than the older 220 − age. Each zone boundary is then a percentage of the reserve added back onto the resting rate.
| Term | Meaning |
|---|---|
| HRmax | Estimated maximum heart rate: 208 − 0.7 × age. |
| HRrest | Resting heart rate, best measured on waking. |
| Reserve | HRmax − HRrest, the usable working range. |
| Zone | A band of intensity defined as a percentage of reserve. |
The inputs explained
| Field | What to enter |
|---|---|
| Age (years) | Your age in years. |
| Resting heart rate (bpm) | Resting heart rate in beats per minute, ideally measured lying down shortly after waking, before getting up. |
When to use it
Structuring endurance training
Most endurance programmes place the bulk of volume in zones 1 and 2, with a smaller proportion of hard work in zones 4 and 5. The common error is spending too much time in the moderate middle, which is tiring without being especially productive.
Keeping easy days genuinely easy
Zone 2 usually feels slower than expected. Holding to it is what allows the hard sessions to be genuinely hard, and it is the most frequently ignored part of a training plan.
Tracking fitness over time
A falling resting heart rate generally indicates improving aerobic fitness. Recalculating the zones every few months keeps them matched to your current condition.
Setting interval targets
Zones 4 and 5 define threshold and maximal work. Use them as upper bounds for interval sessions rather than targets to sit in continuously.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
Training zones at different ages
Zones for a resting heart rate of 60 bpm across a range of ages.
| Age | Maximum heart rate | Zone 2 · endurance (60-70%) | Zone 4 · threshold (80-90%) |
|---|---|---|---|
| 20 years | 194 bpm | 140 – 154 bpm | 167 – 181 bpm |
| 30 years | 187 bpm | 136 – 149 bpm | 162 – 174 bpm |
| 40 years | 180 bpm | 132 – 144 bpm | 156 – 168 bpm |
| 50 years | 173 bpm | 128 – 139 bpm | 150 – 162 bpm |
| 60 years | 166 bpm | 124 – 134 bpm | 145 – 155 bpm |
| 70 years | 159 bpm | 119 – 129 bpm | 139 – 149 bpm |
How resting heart rate shifts the zones
The same age with different resting heart rates, showing why the Karvonen method individualises better than a plain percentage of maximum.
| Resting heart rate | Zone 1 · recovery (50-60%) | Zone 2 · endurance (60-70%) | Zone 4 · threshold (80-90%) |
|---|---|---|---|
| 45 bpm | 116 – 130 bpm | 130 – 144 bpm | 159 – 173 bpm |
| 50 bpm | 119 – 132 bpm | 132 – 146 bpm | 160 – 173 bpm |
| 55 bpm | 121 – 134 bpm | 134 – 147 bpm | 161 – 174 bpm |
| 60 bpm | 124 – 136 bpm | 136 – 149 bpm | 162 – 174 bpm |
| 70 bpm | 129 – 140 bpm | 140 – 152 bpm | 164 – 175 bpm |
| 80 bpm | 134 – 144 bpm | 144 – 155 bpm | 166 – 176 bpm |
Questions
Why not use 220 minus age?
The 220 − age rule was never derived from rigorous research and has a large standard error. The Tanaka equation used here, 208 − 0.7 × age, fits the population data considerably better, though individual variation remains wide either way.
How do I find my true maximum heart rate?
Only through a maximal effort test, ideally supervised. Any age-based formula is an estimate with substantial individual variation. If you have a cardiac condition or are new to intense exercise, speak to a doctor before attempting maximal efforts.
What is the difference between Karvonen and percentage of maximum?
Percentage of maximum takes a straight fraction of HRmax. Karvonen works from the reserve above your resting rate, which produces zones better matched to individual fitness: particularly for well-conditioned people with low resting rates.
When should I measure resting heart rate?
Lying down shortly after waking, before getting up or consuming caffeine. Averaging across several mornings gives a more stable figure than any single reading.
How much time should I spend in each zone?
Many endurance programmes use roughly 80 per cent of training time in the easy zones and 20 per cent hard. The right distribution depends on your goals, training history and available time.
For aerobic fitness testing, see the VO₂ max calculator. For session energy cost, use calories burned.