Training Heart Rate Calculator - Heart Rate Zones & HRmax

Five zones, one number - your age

Your maximum heart rate drops by roughly 1 beat per year. A 25-year-old peaks at about 195 bpm. At 40, that ceiling falls to 180 bpm. Every training zone is a percentage of that ceiling, so your age alone defines the entire map. Add a resting heart rate measurement and the Karvonen method refines those zones further - especially useful if your resting pulse is unusually low (fit athlete) or high (deconditioned beginner).

How to calculate your training zones - step by step

Age - enter your age in years. The calculator uses the standard formula HRmax = 220 - age. This gives a population average - individual variation is about +/- 10 bpm. Range: 15-100 years.
Resting heart rate (optional) - measure in the morning right after waking up, lying still for 5 minutes. Count beats for 60 seconds or use a smartwatch/chest strap. Typical values: athletes 40-60 bpm, active adults 60-80 bpm, sedentary 70-100 bpm. Lower is generally better - it indicates a stronger, more efficient heart.
Calculation method - choose Simple (220 - age) for a quick estimate, or Karvonen for personalized zones. Karvonen uses Heart Rate Reserve (HRR = HRmax - RHR) and adds your resting HR back, which shifts zones upward for fit individuals and downward for beginners.
Read your zones - five zones from Zone 1 (warm-up, 50-60%) to Zone 5 (HIIT, 90-100%). Each zone shows a bpm range and its primary training purpose.

Heart rate zones reference

Zone	% of HRmax	Purpose	Duration	Feel
Zone 1	50-60%	Warm-up, recovery, cool-down	30-60 min	Very easy, full conversation
Zone 2	60-70%	Fat burning, aerobic base	45-90 min	Comfortable, can talk in sentences
Zone 3	70-80%	Aerobic endurance, tempo runs	30-60 min	Moderate effort, short phrases only
Zone 4	80-90%	Anaerobic threshold, lactate work	20-40 min	Hard, difficult to speak
Zone 5	90-100%	VO2max, HIIT, sprints	1-5 min intervals	All-out, cannot sustain

Simple vs Karvonen: how the two methods compare

Zone	Simple (age 30)	Karvonen (age 30, RHR 55)	Difference
Zone 1 (50-60%)	95-114 bpm	123-136 bpm	+28 bpm
Zone 2 (60-70%)	114-133 bpm	136-150 bpm	+17 bpm
Zone 3 (70-80%)	133-152 bpm	150-163 bpm	+11 bpm
Zone 4 (80-90%)	152-171 bpm	163-177 bpm	+6 bpm
Zone 5 (90-100%)	171-190 bpm	177-190 bpm	+6 bpm

Karvonen shifts lower zones up significantly for fit individuals (low RHR), making Zone 2 more accurately reflect actual fat-burning effort.

Practical examples

Beginner runner, age 35
HRmax: 185 bpm. Fat burning zone (Zone 2): 111-130 bpm.
Start with 30-minute runs entirely in Zone 2. If you cannot hold a conversation, slow down.

Trained cyclist, age 28, RHR 48 bpm (Karvonen)
HRmax: 192 bpm. Endurance zone (Zone 3): 149-163 bpm.
Long rides in Zone 2-3. Threshold intervals (Zone 4): 163-178 bpm for 2x20 min.

HIIT enthusiast, age 22
HRmax: 198 bpm. Zone 5 (HIIT): 178-198 bpm.
Sprint intervals: 30 sec at Zone 5, 90 sec recovery at Zone 1-2. Repeat 8-12 times.

Senior staying active, age 62
HRmax: 158 bpm. Safe cardio zone (Zone 2): 95-111 bpm.
Brisk walking or light cycling in Zone 2. Avoid Zone 5 without medical clearance.

Marathon prep, age 40, RHR 52 (Karvonen)
HRmax: 180 bpm. Marathon pace (Zone 3): 142-152 bpm.
Long runs at Zone 2 (130-142 bpm). Tempo runs at Zone 3. Threshold work at Zone 4 (152-163 bpm).

FAQ

Is the 220 - age formula accurate?

It is a population average with a standard deviation of about +/- 10-12 bpm. That means roughly 1 in 3 people have an actual HRmax more than 10 bpm away from the prediction. For a precise number, do a graded exercise test (GXT) or a field test: after a thorough warm-up, run a steep hill at maximum effort for 2-3 minutes, then check your peak HR. The Tanaka formula (208 - 0.7 x age) is slightly more accurate for older adults but the difference is small.

Why does Karvonen give higher zones for athletes?

A trained athlete with a resting HR of 45 bpm has a much larger heart rate reserve (HRmax - RHR) than a sedentary person at 80 bpm. Karvonen calculates zones as percentages of that reserve, then adds RHR back. This means a fit person's Zone 2 starts at a higher absolute bpm than a beginner's - which matches real-world effort levels more accurately. The simple method ignores fitness level entirely.

How do I measure resting heart rate correctly?

The gold standard: measure first thing in the morning, before getting out of bed, after a normal night's sleep (no alcohol the night before). Lie still for 5 minutes, then count your pulse for 60 seconds. Use a chest strap or optical HR monitor for consistency. Take the average of 3-5 consecutive mornings - single readings fluctuate due to sleep quality, stress and hydration. A smartwatch that tracks overnight HR can automate this.

Which zone burns the most fat?

Zone 2 (60-70% HRmax) uses the highest percentage of fat as fuel - about 60-70% of calories come from fat oxidation. But Zone 3-4 burns more total calories per minute, so the absolute grams of fat burned can be similar or higher despite a lower percentage. For weight loss, total calorie expenditure matters more than fat percentage. Zone 2 is still optimal for long sessions because it is sustainable for 60-90+ minutes without excessive fatigue.

Can medications affect my heart rate zones?

Yes. Beta-blockers (metoprolol, atenolol, propranolol) lower both resting and maximum heart rate by 20-30 bpm. If you take a beta-blocker, the 220 - age formula will overestimate your HRmax. Use the Karvonen method with your medicated resting HR, or better yet, do a field test to find your actual medicated HRmax. Caffeine, decongestants and stimulants temporarily raise HR. Consult your physician before high-intensity training on cardiac medication.

How often should I retest my resting heart rate?

Every 4-8 weeks during a training block. As your cardiovascular fitness improves, your resting HR will drop - sometimes by 5-15 bpm over several months of consistent training. This shift changes your Karvonen zones and can mean the difference between training in Zone 2 and Zone 3. A declining RHR is one of the best indicators that your training is working.

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