What heart rate zones are for
Effort is easy to misjudge. The run that feels moderate is often too hard; the interval that feels brutal may not be hard enough. Your heart rate is the referee — an objective readout of how hard your body is actually working, whatever your legs claim. Zone training splits the range between resting and maximal into bands, each tied to a different adaptation: easy aerobic building in the lower zones, threshold work in the middle, top-end power at the peak.
This calculator estimates your maximum heart rate from your age, then carves out five zones. Add your resting heart rate and it switches to the Karvonen method, which produces noticeably more personalised bands — more on that below.
Estimating your max heart rate
The formula everyone knows — 220 minus age — dates from the 1970s and survives on convenience. Research since (notably Tanaka's 2001 study of thousands of subjects) suggests 208 − 0.7 × age fits better, especially past middle age: at 60, the classic formula says 160 while Tanaka says 166, and the older formula's habit of underestimating older adults is well documented. The calculator shows both.
Either way, hold the number loosely. True max heart rate varies person to person by 10–20 beats around any formula — it's genetics, not fitness. If your watch has seen you finish a hill sprint at 195 when the formula says 180, believe the watch.
The five training zones
| Zone | % of max HR | Feels like | Builds |
|---|---|---|---|
| 1 | 50–60% | Easy conversation | Recovery, base |
| 2 | 60–70% | Comfortable, sentences OK | Aerobic endurance |
| 3 | 70–80% | Working, short phrases | Aerobic power |
| 4 | 80–90% | Hard, few words | Threshold, speed |
| 5 | 90–100% | Maximal, no talking | Peak power, sprints |
The counterintuitive coaching truth: most training should happen in zones 1–2. Elite endurance athletes famously spend around 80% of their time there, saving the painful zones for a couple of focused sessions a week.
The Karvonen method: why resting heart rate improves everything
Plain percentage-of-max zones ignore something important: fitness lives at the bottom of your heart rate range, not the top. As you get fitter your resting heart rate falls while your max barely moves. Karvonen's method uses that — it takes your heart rate reserve (max minus resting) and adds percentages of it back onto your resting rate. Two 40-year-olds share a formula max of 180, but if one rests at 50 and the other at 75, their 70% targets come out 15 beats apart. That's the personalisation the plain formula throws away.
Measure resting heart rate properly: in bed, just after waking, before coffee. A week of morning readings averaged out beats any single measurement. One safety note that belongs here rather than in fine print: if you take beta-blockers or have any heart condition, formula zones don't apply to you — get zones from your doctor, not a calculator.
Frequently asked questions about heart rate zones
What is target heart rate zone training?
Training zones use a percentage of maximum heart rate to guide intensity — warm-up, fat burn, cardio, and peak effort ranges for structured workouts.
How is max heart rate estimated?
The common formula is 220 minus your age. It is a rough average — individual max heart rate can differ by 10–20 beats per minute.
Who should talk to a doctor before zone training?
People with heart disease, high blood pressure, on beta-blockers, or returning from a long break should get medical clearance first.
How do I use this target heart rate calculator?
Enter age and optional resting heart rate, then click Calculate to see max HR and training zones.
Sources and further reading
- Tanaka H et al. — Age-predicted maximal heart rate revisited (JACC, 2001)
- American Heart Association — Target heart rates chart
- CDC — Measuring physical activity intensity by heart rate
This page is for general information only and is not medical advice. Get medical clearance before intense exercise if you have heart or blood pressure conditions.