Five training zones, properly calculated
Five training zones, properly calculated
The familiar formula is 220 minus age. It is easy to remember and not very accurate — the standard deviation is around 10–12 beats per minute, meaning a substantial share of people are 20 or more beats away from their estimate.
The Tanaka formula performs better across age groups and is what this calculator uses:
Max HR = 208 − (0.7 × age)
At 32, that gives about 186 bpm, compared with 188 from the older formula. The gap widens with age: at 60, Tanaka gives 166 while 220-minus-age gives 160.
The only accurate way to know your true maximum is a supervised test, and that is not appropriate for everyone. If you use a chest-strap monitor regularly, the highest reading you have seen during genuinely hard effort is often closer to reality than any formula.
Simple percentage-of-max zones ignore your resting heart rate, which means a highly conditioned person with a resting rate of 45 and an untrained person at 75 receive identical zones despite very different cardiovascular capacity.
The Karvonen method fixes this by working from heart rate reserve — the span between resting and maximum:
Target = ((Max HR − Resting HR) × intensity%) + Resting HR
This produces zones that reflect your actual conditioning. Measure resting heart rate in the morning before getting up, ideally averaged across several days.
Zone 1 (50–60%) — Recovery. Very light. Promotes blood flow and recovery between hard sessions. Should feel almost too easy.
Zone 2 (60–70%) — Aerobic base. Conversational pace, sustainable for hours. Builds mitochondrial density and fat oxidation. The majority of endurance training happens here, and most recreational athletes do far too little of it.
Zone 3 (70–80%) — Tempo. Comfortably hard; speaking becomes limited to short phrases. Improves lactate clearance and sustainable pace.
Zone 4 (80–90%) — Threshold. Hard, sustainable for perhaps 20–60 minutes. This is where lactate threshold improves, and it is the zone most associated with race-pace gains.
Zone 5 (90–100%) — VO₂ max. Very hard, sustainable in intervals of a few minutes at most. Develops maximal aerobic capacity. Demanding to recover from, so used sparingly.
A consistent finding across endurance research is that well-trained athletes spend roughly 80% of training time in zones 1–2 and 20% in zones 4–5, with relatively little in zone 3.
The reasoning is that easy work builds aerobic capacity with low recovery cost, while hard work drives high-end adaptation. Zone 3 sits awkwardly between — hard enough to require real recovery, not hard enough to produce the strongest adaptations.
The common recreational pattern is the opposite: most sessions land in zone 3 because that is what “a proper workout” feels like. The result is accumulated fatigue with modest progress. Running easy days genuinely easy is the most frequent single improvement available to amateur endurance athletes.
Heart rate is influenced by more than intensity. Heat and humidity raise it at the same effort, sometimes by 10–20 beats. Dehydration raises it. Poor sleep, illness, caffeine, stress, and altitude all shift it. There is also cardiac drift — heart rate climbing over a long steady effort even as pace stays constant.
Some medications, particularly beta blockers, lower heart rate substantially and make percentage-based zones meaningless. If you take one, ask your doctor how to gauge intensity.
For these reasons, pairing heart rate with perceived exertion is more reliable than either alone. If the number says zone 2 but the effort feels like zone 4, trust the effort.
If you have a heart condition, high blood pressure, chest pain during exertion, or have been inactive for a long period, speak to a doctor before beginning structured high-intensity training. These zones are general guidance for healthy adults and cannot account for individual cardiac risk.
Not particularly. The standard deviation is around 10-12 beats per minute, so many people differ from the estimate by 20 or more. The Tanaka formula, 208 minus 0.7 times age, performs better across age groups.
A method that calculates zones from heart rate reserve - the span between resting and maximum heart rate - rather than from maximum alone. It produces zones that reflect your actual conditioning rather than age alone.
Lower zones use a higher proportion of fat for fuel, but higher zones burn more total calories. For fat loss, total energy expenditure and diet matter far more than which zone you train in.
Endurance research consistently points to roughly 80% of training time in easy zones 1-2 and 20% in hard zones 4-5, with little in between. Most recreational athletes train too hard on easy days and too easy on hard days.