Heart Rate Zones Calculator
Calculate your personalised 5 heart rate training zones for optimal cardio workouts using the Karvonen method.
How This Calculator Builds Your Zones
This tool uses the Karvonen (heart rate reserve) method, which is more personal than simple percentages of max heart rate. It works on your heart rate reserve (HRR) — the gap between your resting and maximum heart rates:
Target HR = Resting HR + (% intensity × (Max HR − Resting HR))
Because it anchors to your resting heart rate, the Karvonen method automatically adjusts as your fitness improves — a fitter heart with a lower resting rate gets correspondingly lower zone boundaries.
The Five Training Zones
| Zone | % HRR | Feels Like | Main Benefit |
|---|---|---|---|
| Zone 1 — Recovery | 50–60% | Very easy, full conversation | Active recovery, circulation |
| Zone 2 — Endurance | 60–70% | Comfortable, can talk in sentences | Fat oxidation, aerobic base, mitochondria |
| Zone 3 — Tempo | 70–80% | Working, short phrases only | Aerobic capacity, muscular endurance |
| Zone 4 — Threshold | 80–90% | Hard, a few words at most | Lactate threshold, race pace |
| Zone 5 — VO₂max | 90–100% | Maximal, unsustainable | Peak power and VO₂max |
Worked Example
A 30-year-old with a resting heart rate of 60 bpm: estimated max HR = 220 − 30 = 190, so HRR = 190 − 60 = 130. Zone 2 runs from 60 + (0.60 × 130) = 138 bpm to 60 + (0.70 × 130) = 151 bpm. Without the Karvonen correction, plain %-of-max would have given 114–133 bpm — a band so low this athlete would barely be jogging.
Getting Your Two Inputs Right
Resting heart rate: measure for 60 seconds immediately after waking, before coffee or standing up, for three mornings and average them. Wearables that track sleeping heart rate give a good equivalent.
Maximum heart rate: 220 − age is the convention but has a standard deviation of ±10–12 bpm. The Tanaka formula (208 − 0.7 × age) is slightly better for adults over 40. If you train seriously, a field test — e.g. the highest value seen at the end of an all-out 4–5 minute hill effort, done only when healthy and ideally cleared by a doctor — beats any formula.
How To Distribute Your Training
Most successful endurance programmes follow a roughly 80/20 split: about 80% of weekly training time in zones 1–2 and 20% in zones 4–5, with surprisingly little time in zone 3. Beginners almost always train their easy days too hard and their hard days too easy, ending up permanently in the "moderately tired, slowly improving" middle. If your easy runs creep above zone 2, slow down — walking breaks count.
For the full training context, see our heart rate training guide. Runners can convert zone efforts to target speeds with the running pace calculator, and you can estimate session energy cost with the calories burned calculator.
Frequently Asked Questions
Why is my heart rate high even on easy runs?
Common causes: heat, dehydration, poor sleep, caffeine, stress, or simply running too fast — most new runners' 'easy' pace is actually zone 3. Slow down until you can speak full sentences; if resting heart rate is also elevated, prioritise recovery.
Do I burn more fat in the 'fat-burning zone'?
Zone 2 burns the highest percentage of calories from fat, but higher zones burn more total calories — and total energy balance determines fat loss. Train zone 2 for aerobic adaptations and sustainability, not because it melts fat preferentially.
Are watch-measured heart rate zones accurate?
Wrist optical sensors are good at steady efforts but lag during intervals and misread during weight training or rough water. A chest strap is meaningfully more accurate for zone work. Also check what your watch uses — many default to % of max HR, not Karvonen.
My max heart rate is higher than 220 minus my age. Is that bad?
No. The formula is a population average with a spread of ±10–12 beats; healthy individuals routinely exceed it. If you've observed a higher value during hard training, use that observed maximum in the calculator instead — your zones will be more accurate.