ZOVATOOL

Target Heart Rate Calculator

Max HR (Tanaka)
187 bpm
Max HR (Fox 220−age)
190 bpm
Max HR (Tanaka M)
186 bpm
Heart Rate Reserve
122 bpm
Karvonen method
Training Zones (Karvonen: %HRR + RHR)
Zone 1 — Recovery126–138 bpm
%HRmax: 94–112 bpm
Zone 2 — Fat burn / Endurance138–150 bpm
%HRmax: 112–131 bpm
Zone 3 — Aerobic150–163 bpm
%HRmax: 131–150 bpm
Zone 4 — Anaerobic / Threshold163–175 bpm
%HRmax: 150–168 bpm
Zone 5 — Max / VO₂175–187 bpm
%HRmax: 168–187 bpm
Formulas
Fox: HRmax = 220 − age
Tanaka: HRmax = 208 − 0.7 × age
Gulati (women): HRmax = 206 − 0.88 × age
Karvonen: Target = (HRmax − RHR) × intensity% + RHR

How to use the Target Heart Rate Calculator

  1. Enter age; select formula (Tanaka 208−0.7×age is more accurate than 220−age over 40).
  2. Enter resting heart rate (measured first thing in the morning for 1 minute).
  3. Calculator returns maximum heart rate and heart rate reserve (max − rest).
  4. Choose between %HR-max and Karvonen (%HR-reserve) — Karvonen is more personal.
  5. Read all 5 training zones — Z1 recovery, Z2 aerobic base, Z3 tempo, Z4 threshold, Z5 VO2max.
  6. Set a workout target — the zone you want to spend most time in.
  7. Read the specific bpm range for that zone.
  8. For fat burn focus: Zone 2 (60–70%) uses highest percentage from fat.
  9. For total calorie burn: Zone 4 (85–95%) burns more absolute calories.
  10. Combine with wearable to auto-alert when drifting out of zone.
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Heart rate training zones: what the numbers actually mean for fitness

Heart rate training divides effort into zones based on percentage of maximum heart rate. It's the most-used method for cardio pacing because heart rate reflects real physiological stress — unlike pace, which varies with terrain, weather and fatigue. Get your zones right and every session has a purpose; get them wrong and you spend months training the same middle-intensity 'grey zone' that improves nothing efficiently.

Estimating max heart rate is where errors start. The classic '220 − age' formula was a rough regression from 1970s data with ±10–15 bpm error. Tanaka (208 − 0.7 × age) is more accurate, especially for adults over 40. Even better: run an all-out 3–5 minute effort (uphill hard, safe conditions), take the highest reading; that's within ±3 bpm of true max. Formulas are estimates, not truth.

Karvonen's formula improves personalization: Target HR = (max HR − rest HR) × intensity% + rest HR. Uses your heart rate reserve — the difference between max and resting — as the effort scale. A fit person with low resting HR gets a lower target than 220−age would suggest, which matches the training reality better. Wearables like Polar and Garmin default to Karvonen for this reason.

The 5-zone system is what most training plans use. Zone 1 (50–60%): active recovery, warm-up, cool-down. Zone 2 (60–70%): aerobic base, mitochondrial density, fat oxidation — elite endurance athletes spend 70–80% of training here. Zone 3 (70–80%): tempo, marathon pace, 'no man's land' that many amateurs live in. Zone 4 (80–90%): lactate threshold, 10K to half marathon pace. Zone 5 (90–100%): VO2max intervals, short and painful, drives peak fitness.

The 80/20 principle — 80% of training in Zone 1–2, 20% in Zone 4–5, minimal in Zone 3 — is the pattern of world-class endurance athletes across running, cycling, cross-country skiing and rowing (Seiler et al., 2010–2020). Amateurs typically flip this: 60% grey-zone Z3, 30% easy, 10% hard. Reversing that pattern is the single biggest fitness upgrade for most recreational endurance athletes. The heart rate calculator sets the boundaries; discipline holds them.