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Running & Fitness

Heart Rate Zone Calculator

Find your 5 training zones using modern HR-max formulas. Optionally use HR Reserve (Karvonen) for fitness-adjusted ranges.

First thing in morning, lying down.
Karvonen accounts for resting HR, giving zones better matched to your fitness.

Your numbers

187bpm
Estimated HR-max
HR-max (estimate)
187 bpm
Resting HR
60 bpm
HR Reserve (HRR)
HR-max − resting HR
127 bpm
Most accurate way to find HR-max: a max-effort field test (after warm-up, run/cycle as hard as you can sustain for 4–5 min, finish with a sprint). Formulas estimate within ±10–15 bpm.
Training zones (% of HR-max)
Zone 1 — Recovery
Very light. Active recovery, warm-up, cool-down.
94–112
bpm · 50–60%
Zone 2 — Endurance
Conversational pace. Aerobic base building. 80% of training time should be here.
112–131
bpm · 60–70%
Zone 3 — Aerobic
Comfortably hard. Improves aerobic capacity. The "gray zone" — easy to overdo.
131–150
bpm · 70–80%
Zone 4 — Threshold
Hard. Lactate threshold. 20–60 min reps build sustainable speed.
150–168
bpm · 80–90%
Zone 5 — VO2max
Very hard. 3–8 min intervals. Builds peak aerobic capacity. Use sparingly.
168–187
bpm · 90–100%

What are heart rate zones?

Training zones divide effort into bands based on heart rate — usually 3, 5, or 7 zones depending on the model. The 5-zone model is the most common: from very easy recovery to all-out VO2max work. Different zones drive different physiological adaptations. Smart training spends specific amounts of time in each zone, not random hard-easy mixes.

HR-max formulas: which to use

  • Tanaka (2001): 208 − 0.7 × age. The modern best-fit average. Standard deviation ~10 bpm.
  • Haskell (1971): 220 − age. Famous, classic, less accurate. Underestimates for older adults, overestimates for younger.
  • Gulati (2010): 206 − 0.88 × age. Derived specifically from a women-only sample. More accurate for women than Tanaka.
  • Field-tested HR-max: most accurate. A supervised graded exercise test or all-out field interval session.

All formulas have ±10–15 bpm individual variation. If your zones feel systematically off (e.g., Zone 2 feels harder than “easy” should), your real HR-max is probably different from the formula.

Karvonen vs % HR-max

Two ways to calculate zones:

  • % HR-max: Zone X = X% × HR-max. Simple, but doesn't adjust for individual fitness. A fit person and unfit person of the same age get the same zones.
  • Karvonen / HR Reserve: Zone X = resting HR + X% × (HR-max − resting). Adjusts to fitness — a fit person with a low resting HR gets a wider band of useful zones.

For most amateur athletes, Karvonen gives more useful zone targets. The differences shrink as resting HR rises (i.e., for less-fit individuals, the two methods converge).

The 5 zones, in detail

Zone 1: Recovery (50–60%)

Very easy. Active recovery rides/runs, warm-ups, cool-downs. Should feel laughably easy. Many people skip this zone entirely — but it's where you build aerobic base without accumulating fatigue.

Zone 2: Endurance (60–70%)

Conversational pace. The bread-and-butter of endurance training. Most of your weekly volume should be here. Builds mitochondrial density, fat oxidation, and aerobic capacity. If you can hold a conversation, you're probably in this zone.

Zone 3: Aerobic / Tempo (70–80%)

Comfortably hard. The infamous “gray zone.” Useful in moderation (steady-state efforts, tempo runs), but easy to spend too much time here without getting the benefits of either easy training or true high-intensity work.

Zone 4: Threshold (80–90%)

Hard. Right at lactate threshold — the pace you can hold for ~1 hour all-out. Improves your ability to clear lactate and run at sustained high speeds. Tempo workouts and threshold intervals (10–20 min reps) live here.

Zone 5: VO2max (90–100%)

Very hard, can only sustain 3–8 minutes per rep. Builds peak aerobic capacity. Used in interval workouts (4 × 4 min, 5 × 3 min, etc.). Don't do this every day — it requires recovery. 1–2 sessions per week max.

Polarized training: 80/10/10

Endurance research consistently finds that elite athletes spend ~80% of their training time in Zones 1–2 (easy), ~10% in Zone 4 (threshold), and ~10% in Zone 5 (VO2max). They spend almost no time in Zone 3 — it's too easy to drive high-intensity adaptations and too hard to allow real recovery for the next quality session.

Most amateur runners do the opposite: too much Zone 3, not enough easy, not enough hard. The fix: discipline yourself to truly run easy on easy days, even if it means walking up hills, even if it feels embarrassingly slow. The fitness gains come from the contrast.

When HR is unreliable

  • First 10 minutes of a workout — HR lags behind effort. Use perceived effort early.
  • Heat and humidity — HR runs 5–15 bpm higher at the same pace. Don't panic.
  • Caffeine — can elevate HR by 5–10 bpm without changing effort.
  • Dehydration — raises HR for the same workload (“cardiac drift”).
  • Illness, lack of sleep — HR rises. If your warmup HR is >5 bpm above normal, consider a recovery day.
  • Wrist-based optical sensors — often inaccurate during high-intensity intervals. Chest straps are more reliable.

Pair this with our Pace Calculator for running workouts and the TDEE Calculator to match daily calorie intake to training volume.

Frequently Asked Questions

How accurate is "220 − age" for HR-max?▾
It's a rough estimate with a standard deviation of ~10–12 bpm. The Tanaka formula (208 − 0.7 × age) is more accurate on average — published in 2001 from a meta-analysis of HR-max studies. For women, Gulati (206 − 0.88 × age) is the most accurate. The most accurate way is a supervised field or lab test.
How do I find my HR-max via field test?▾
After 10–15 min easy warm-up, run hard for 4 minutes (sustainable at lactate threshold), recover 2 minutes easy, then run all-out for 4 more minutes finishing with a 30-second sprint. Your peak HR during the test is close to your true HR-max. Repeat occasionally — HR-max declines slowly with age.
What's HR Reserve (Karvonen) and why use it?▾
HR Reserve = HR-max − resting HR. The Karvonen method calculates zones as percentages of HRR added to resting HR, rather than percentages of HR-max alone. This adjusts zones to your fitness — a fit athlete with low resting HR gets more useful zone bands than the simple % HR-max method gives them.
How much time should I spend in each zone?▾
For most endurance training: ~80% in Zone 1–2 (easy/aerobic), ~10% in Zone 4 (threshold), ~10% in Zone 5 (VO2max intervals). Avoid spending too much time in Zone 3 ("gray zone") — it's too hard to be truly easy and too easy to drive max-effort adaptations. This 80/10/10 distribution is sometimes called "polarized" training.
Why is my HR higher running than cycling at the same effort?▾
Different muscles, different heat dissipation, different posture. Cycling HR is typically 5–15 bpm lower than running at equivalent perceived effort because cycling uses less muscle mass. Some athletes maintain sport-specific HR-max values. If you train both, test for each.

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Running pace + race splits
TDEE Calculator
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Daily hydration