Heart Rate Calculator

Heart Rate Calculator — evidence-based tool to check your heart rate. Includes formula, tips, and interpretation guide.

A heart rate zones calculator divides your aerobic training range into zones (typically 5 or 7) based on your maximum heart rate (HRmax) or lactate threshold heart rate. Each zone targets a different physiological adaptation — Zone 1 builds aerobic base and promotes recovery, Zone 3 develops tempo endurance, and Zone 5 trains speed and VO2max. Training in the correct zone for each session type is the foundation of periodised endurance training.

Used by runners, cyclists, triathletes, rowers, and any endurance athlete to structure training intensity, monitor fatigue, and accelerate performance improvements.

Estimate or measure your maximum heart rate — the most common formula is 220 − age (±10–15 bpm individual variation).
For more accuracy, use a lab test, a field test (5-minute all-out effort), or a 30-minute threshold test to find your actual HRmax or lactate threshold HR.
The calculator computes 5-zone boundaries (Karvonen method optionally uses resting HR for personalisation).
Match each training session type to the appropriate zone as prescribed by your training plan.

Heart rate zone formulas

Estimated HRmax = 220 − age (±10–15 bpm — significant individual variation exists)

Karvonen formula (Heart Rate Reserve method): Target HR = HRrest + intensity% × (HRmax − HRrest)

5-Zone model (% HRmax): Z1: 50–60%, Z2: 60–70%, Z3: 70–80%, Z4: 80–90%, Z5: 90–100%

VO2max estimate: VO2max ≈ 15 × (HRmax / HRrest) — rough Uth-Sørensen-Overgaard-Pedersen formula

Your training zones explained

Purpose of each zone

Z1 (Recovery, <60% HRmax): active recovery, warm-up, cool-down. Z2 (Endurance, 60–70%): aerobic base building — the "all day" pace; most endurance volume should be here. Z3 (Tempo, 70–80%): comfortably hard, sustainable for 30–60 minutes — builds efficiency. Z4 (Threshold, 80–90%): at or near lactate threshold, sustainable for 10–30 minutes — improves threshold pace. Z5 (VO2max, >90%): intense intervals of 3–8 minutes — improves maximal aerobic capacity.

Health tips and best practices

The 220−age formula can be inaccurate by ±10–20 bpm for many individuals — field test or lab test your actual HRmax for precision training.
Heart rate lags behind effort by 30–60 seconds — use perceived exertion to control intensity at the start of intervals, then check HR.
Cardiac drift: heart rate rises over time at a constant pace during long runs — especially in heat — without an actual intensity increase.
Polarised training (80% Z1–2, 20% Z4–5) has strong research support for endurance performance — avoid spending too much time in Z3.

Elite endurance athletes typically spend 70–80% of training volume in low intensity (Z1–2), 5–10% in moderate intensity (Z3), and 15–20% in high intensity (Z4–5).
VO2max for elite male marathon runners averages 70–80 ml/kg/min; for elite women, 60–70 ml/kg/min; sedentary adults average 30–40 ml/kg/min.
A resting heart rate below 60 bpm is typical for trained endurance athletes — some elite cyclists have resting rates of 32–38 bpm.

Common mistakes to avoid

Training too much in Z3 (the "grey zone") — too hard to recover from quickly, not intense enough to drive the highest adaptations; often called "junk miles" in HR terms.
Using HRmax = 220 − age without adjustment — at age 50 this estimates HRmax at 170, but actual values commonly range from 155 to 185 bpm.
Ignoring individual variation — two athletes of the same age and fitness may have HRmax values 20+ bpm apart.

Heart rate training zones are general guidelines. Individuals with cardiovascular conditions, arrhythmias, or those taking heart rate-affecting medications (e.g. beta-blockers) should consult a cardiologist before using heart rate targets for exercise intensity. Get medical clearance before starting a high-intensity training programme.