Heart Rate Zones Calculator
Estimate your max heart rate (Tanaka, Fox, or Gulati) and five training zones for running and cycling. Enter resting HR to switch to the Karvonen heart-rate-reserve method.
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Your estimated maximum heart rate is .... Use the table below to target a specific training zone.
| Zone | Intensity (low) | Intensity (high) | BPM (low) | BPM (high) |
|---|---|---|---|---|
What the zones are for — Zone 1 (50–60%): recovery and warm-up, very easy effort. Zone 2 (60–70%): aerobic base and endurance, the conversational long-run pace. Zone 3 (70–80%): aerobic / tempo, moderately hard sustained work. Zone 4 (80–90%): lactate threshold, hard efforts you can hold for a limited time. Zone 5 (90–100%): VO2 max, maximal short intervals.
What Heart Rate Zones Are For
Endurance training is more efficient when you spend time in the right intensity for the adaptation you want. Long slow runs build aerobic base; tempo work raises lactate threshold; intervals push VO2 max. The heart-rate zone framework — popularized by Joe Friel, Daniels, and others through the 1990s — gives a simple way to keep yourself honest: "Zone 2 means heart rate between X and Y." Use a watch, stay in the band, and the right adaptation follows.
This calculator estimates your maximum heart rate from age and (optionally) refines zones using resting heart rate through the Karvonen heart-rate-reserve method.
How It Works
Estimating Max Heart Rate
The maximum heart rate decreases with age, but the rate at which it does so is contested. Three formulas covering the realistic range:
| Formula | Equation | Notes |
|---|---|---|
| Fox 220 − age | The classic. Easy to remember; tends to overestimate younger adults and underestimate older adults. | |
| Tanaka | Better fit to a 2001 meta-analysis (n=18,712). Default for most modern coaching guides. | |
| Gulati (women) | 2010 study, women only. Yields lower max than Tanaka for the same age. |
A direct field test (a maximal-effort hill repeat or VO2-max protocol with a chest strap) beats any age formula by a significant margin. Estimates have a standard deviation of around ±10 bpm — so if you already know your true maximum from a hard race or test, select the Measured option and enter it directly rather than estimating from age.
Two Ways to Define the Zones
%HRmax (simpler): Zone bounds are a percentage of estimated max. Zone 1 = 50–60%, Zone 2 = 60–70%, etc.
Karvonen / heart-rate reserve (more individualized): Zones are a percentage of the reserve — the gap between resting and max:
Karvonen accounts for fitter people having lower resting heart rates: at the same %HR-reserve, two people of equal age but different fitness will train at different absolute heart rates, which matches their actual physiological loads better than %HRmax does.
The Five Standard Zones
| Zone | %HR-reserve | Description | Typical use |
|---|---|---|---|
| 1 | 50–60% | Recovery / active rest | Cooldowns, easy days |
| 2 | 60–70% | Aerobic base | Long slow distance |
| 3 | 70–80% | Tempo / steady | Sustained efforts, moderate workouts |
| 4 | 80–90% | Lactate threshold | 20–40 min hard efforts |
| 5 | 90–100% | VO2 max / anaerobic | 1–5 min intervals |
Practical Scenarios
1. Building an Aerobic Base
Most coaches recommend that 70–80% of weekly training time happens in Zones 1–2. Easier said than done — runners famously drift up to Zone 3 because it "feels right." Setting an alarm at the Zone 2 ceiling, then deliberately slowing to stay below it, is one of the highest-ROI training adjustments most amateurs can make.
2. Lactate Threshold Tempo
Workouts at Zone 4 — about 80–90% of HR reserve — drive the largest improvement in sustainable race pace for 5K to half-marathon distances. A common workout: 20 minutes at the Zone 3/4 boundary, twice a week.
3. Recovery Days That Actually Recover
Zone 1 is genuinely easy: heart rate well below conversational threshold. The temptation is to "still run a little hard." Resist it — the point of recovery days is to clear residual fatigue, and zone 1 keeps you honest.
Caveats
- Estimates have wide error bars. The 220 − age formula has been quoted with a standard deviation of ±10–12 bpm. Your true max could be 15+ bpm above or below the estimate.
- Karvonen requires a clean resting HR. Take it first thing in the morning, before getting out of bed, after a normal night's sleep — not after coffee, exercise, or stress. A noisy resting HR poisons the zone calculation.
- Heart rate lags effort. Especially in short intervals — by the time HR catches up to the start of a hard interval, the interval may be half over. Use HR for steady-state efforts; use power, pace, or perceived exertion for short anaerobic work.
- Drift is real. During long efforts, HR drifts upward by 5–10 bpm at constant effort due to dehydration, heat, and fatigue. A pace that started in Zone 2 may slide into Zone 3 by hour two with no actual increase in workload.
Frequently Asked Questions (FAQ)
Which max-HR formula should I use?
For most adults, Tanaka (208 − 0.7·age) is a closer fit to actual measurements than the classic Fox 220 − age. Gulati (206 − 0.88·age) is calibrated specifically for women. None of them beat a direct field test — formulas have a typical standard error of around ±10 bpm.
What is the difference between %HRmax and the Karvonen method?
%HRmax uses a percentage of your maximum heart rate directly. Karvonen uses a percentage of the heart-rate reserve (max minus resting), which accounts for fitness differences. A fitter person with a lower resting HR ends up with the same %HR-reserve target at a different absolute heart rate, which matches actual physiological load more closely.
How do I measure my resting heart rate accurately?
Take it first thing in the morning, lying in bed before getting up, after a normal night's sleep. Avoid coffee, exercise, or stress beforehand. A wearable that reports overnight low-HR is also reliable. Average several mornings rather than trusting a single reading.
Why does my heart rate drift higher during a long run at the same pace?
This is "cardiac drift." During long efforts, HR rises 5–10 bpm over an hour at constant pace because of dehydration, heat, and accumulating fatigue. The same pace becomes a higher-zone effort over time even with no other change.
Disclaimer
Heart rate zones derived from age-based formulas are estimates with a typical error of ±10 bpm or more. They are not medical advice. Anyone with cardiovascular conditions or taking medications that affect heart rate should consult a physician before using these zones for training.