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Target Heart Rate Calculator

Calculate your ideal heart rate zones for fat burning, endurance training, cardio fitness, and peak athletic performance.

Karvonen · Tanaka · 5-zone training modelLast updated 2026-05-15

Educational estimate. Consult a doctor before starting vigorous exercise — especially if you have cardiovascular risk factors or are over 40 and previously sedentary.

years

Used to estimate your maximum heart rate.

Optional
bpm

Measure first thing in the morning, lying still. Used for the Karvonen formula.

What this tool computes

Your maximum heart rate, heart rate reserve, and five training zones (Recovery → VO₂ Max). Pick a goal and we recommend the exact bpm range you should hold during the workout — using the Karvonen formula by default.

Enter your age (or tested max HR) and pick a goal to see your personalised target heart rate zones.

What Is Target Heart Rate?

Target heart rate (THR) is the beats-per-minute window your heart should hold during a workout to achieve a specific training effect. Hold it too low and the session is too easy to drive adaptation; push past it and you move into a different energy system than the one you wanted to train. The American College of Sports Medicine, American Heart Association and every modern endurance coach use heart rate zones to write training plans for runners, cyclists, triathletes and general fitness clients.

The math is simple: estimate your maximum heart rate, then take a percentage range of it (or, more precisely, your heart rate reserve). The art is matching that percentage to your goal — fat-loss athletes, Zone 2 endurance trainees and HIIT performance athletes all sit in very different zones.

Heart Rate Zones Explained

The 5-zone model is the standard used by Polar, Garmin, Wahoo, Apple Fitness, and elite coaches like Stephen Seiler. Each zone corresponds to a different physiological adaptation.

Zone 1 · Recovery

50–60% · Active recovery

Very easy effort. Improves blood flow, accelerates recovery and builds the aerobic base for beginners.

Zone 2 · Fat Burn

60–70% · Fat-burn & aerobic base

Conversational pace. Maximises fat oxidation, builds mitochondrial density and is the cornerstone of endurance training.

Zone 3 · Aerobic

70–80% · Aerobic fitness

Moderately hard. Pushes lactate threshold up, improves stroke volume and cardiovascular efficiency.

Zone 4 · Anaerobic

80–90% · Lactate threshold

Hard. Lactate begins to accumulate. Trains the body to clear lactate and sustain race-pace efforts.

Zone 5 · VO₂ Max

90–100% · Peak performance

Maximum effort. Short intervals only. Develops VO₂ max, top-end speed and neuromuscular power.

Zone 2 Training Benefits

Zone 2 — that comfortable, conversational pace at 60–70% of max HR — has become the most-discussed training intensity in modern endurance literature, thanks to physiologists like Iñigo San Millán and the rise of the "Norwegian method". The evidence is clear that the bulk of an endurance athlete's weekly volume should sit here.

What Zone 2 builds

  • • Mitochondrial density (more cellular energy factories)
  • • Capillary network around slow-twitch muscle fibres
  • • Fat oxidation capacity — fat used per minute
  • • Stroke volume and cardiac output
  • • Lactate clearance and metabolic flexibility

How to do it right

  • • Hold heart rate in your Zone 2 bpm window
  • • Sessions should be 45–90 minutes long
  • • You should be able to speak full sentences
  • • 3–5 sessions per week, low impact (bike, swim, easy run)
  • • Resist the urge to push — most people train Zone 2 too hard

Fat Burn vs Cardio Zone — What Actually Matters

Gym treadmills label Zone 2 as the "fat burn zone" and Zone 3 as the "cardio zone". There is real physiology behind those labels — at lower intensity, a higher share of fuel comes from fat — but the marketing oversimplifies it. For fat-loss specifically, what matters is total calories burned over the week, not the share of those calories that came from fat in any single session. A 60-minute Zone 2 walk burns more total energy (and more fat) than a 20-minute Zone 4 interval session, even though the interval session burns a smaller share of fat.

The practical takeaway: pick the intensity you can sustain consistently. For most adults that's Zone 2 plus some Zone 3. Add Zone 4–5 work once a week for the cardiac and metabolic benefits, but don't make it the whole programme.

How Athletes Use Heart Rate Training

Runners — the 80/20 rule

Elite distance runners spend ~80% of weekly minutes in Zone 1–2 and the remaining ~20% in Zone 4–5. Most age-group runners do the opposite, which is why their fitness plateaus.

Cyclists — power meets pulse

Cyclists use heart rate alongside a power meter. Heart rate validates the work — a steady FTP test at constant watts should also produce a steady HR; HR drift signals fatigue.

HIIT athletes — the 30-second test

Quality HIIT intervals push you well into Zone 5 (90%+ of max). If you can't reach Zone 5 in 30 seconds, the interval is too easy. If you can't recover to Zone 2 between reps, the rest is too short.

Zone 2 trainees — the talk test

If you can speak in full sentences but not sing comfortably, you're in Zone 2. If you can only manage 3-word phrases, you're in Zone 3. The talk test correlates well with heart rate but never lies about effort.

Triathletes — sport-specific maxes

Max HR differs by sport. Run max is typically 5–15 bpm higher than bike max, and bike max higher than swim max. Test each modality separately for accurate sport-specific zones.

Recovery athletes — heart rate variability

HRV (the variation between consecutive beats) is a sensitive early warning for under-recovery. A drop in morning HRV alongside elevated resting HR is the cue to take an easy day.

Disclaimer: This calculator provides estimated heart rate training zones and is not medical advice. Age-based max heart rate formulas carry roughly ±10–15 bpm of error for any individual. Consult a physician before starting a new exercise programme — especially if you are over 40 and previously sedentary, are pregnant, or have a history of cardiovascular disease, hypertension, diabetes or are taking heart-rate altering medications such as beta-blockers.

Frequently Asked Questions

Target heart rate is the beats-per-minute window you should aim for during exercise to drive a specific training adaptation. It's expressed as a percentage of your maximum heart rate (or your heart rate reserve, using the Karvonen formula), and it's how coaches, sports scientists and fitness watches all prescribe cardio intensity.

Zone 2 is steady-state aerobic exercise at roughly 60–70% of your maximum heart rate — easy enough that you can hold a full conversation. It is the cornerstone of modern endurance training because it builds mitochondria, capillary density and fat-oxidation capacity without accumulating fatigue. Elite endurance athletes spend up to 80% of their weekly volume in Zone 2.

The Tanaka, Monahan & Seals (2001) formula — HRmax = 208 − (0.7 × age) — is the most accurate population-level estimate in the published literature. It has a smaller standard error than the classic 220 − age formula, especially for adults over 40. For a precise individual value, only a supervised graded exercise test can replace age-based estimates.

It's a reasonable rough estimate but it overestimates max HR in younger adults and underestimates it in older ones. The original Haskell & Fox formula was never intended as a precision tool — it was derived from a small sample for population-level studies. Tanaka (208 − 0.7·age) and Nes (211 − 0.64·age) are more accurate modern replacements.

The highest share of energy comes from fat at low intensity — roughly Zone 1 to lower Zone 2 (about 55–70% of max HR). However, total fat calories burned per session are highest at moderate Zone 2 to Zone 3 because total energy output is much higher. For fat loss, the deciding factor is total weekly calorie burn, not the in-session fuel mix.

Briefly approaching or hitting your estimated maximum during all-out efforts is normal and not dangerous for healthy adults. Warning signs are dizziness, chest pain, irregular rhythm, extreme breathlessness disproportionate to the effort, or persistently exceeding your estimated max by 15+ bpm. Stop and consult a physician if any of these occur, especially if you have cardiovascular risk factors.

The Karvonen formula uses heart rate reserve (HRR = max HR − resting HR) to set targets: target HR = (HRR × intensity%) + resting HR. It produces more personalised zones than a flat %HRmax because it accounts for your resting fitness — a 60-year-old elite cyclist and a 60-year-old beginner can have the same max HR but very different resting HR, and Karvonen reflects that.

The gold standard is a graded exercise (stress) test under medical supervision. A field test alternative is a maximal 3–4 minute hill effort, fully warmed up, with all-out final 60 seconds — the peak number on a chest-strap monitor is a reasonable proxy. Wrist-based optical sensors are less reliable at very high intensities; use a chest strap for max-effort testing.

Devices use different defaults. Polar, Garmin and Wahoo offer toggles between %HRmax, %HRR (Karvonen) and lactate-threshold-based zones. Apple Watch defaults to %HRR. The bpm output can differ by 5–15 bpm depending on the method and the device's default max HR estimate. Configure your watch with the same max HR and method as this calculator to match.

Yes — at roughly 60–70% of max HR, fat is the dominant fuel source. But total fat oxidation depends on session length more than intensity. A 60-minute Zone 2 ride burns more total fat than a 30-minute Zone 4 effort, even though the Zone 4 session burns more total calories. For fat loss outcomes, weekly volume of Zone 2 work tends to beat short, harder sessions.

Yes. Beta-blockers can reduce max HR by 20–50 bpm depending on dose. Other medications — calcium-channel blockers, certain antidepressants, thyroid drugs — can also affect resting or peak HR. If you take any heart-rate-altering medication, ask your physician for a medication-adjusted max HR estimate or rely on perceived exertion (Borg RPE) instead.

Pregnant individuals should follow ACOG (American College of Obstetricians and Gynecologists) guidance, which favours rating-of-perceived-exertion over fixed heart rate targets because resting and exercise HR change throughout pregnancy. This calculator is not designed for pregnancy-specific intensity prescription — consult your obstetrician or a perinatal exercise specialist for an individualised plan.

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