What are heart rate zones?

Heart rate zones divide your effort during exercise into 5 distinct ranges, each producing different training adaptations. Training in specific zones optimizes for specific goals: Zone 2 (60-70% of max HR) is the famous ‘fat burning’ zone but more importantly builds aerobic capacity – the foundation of endurance. Zone 3-4 (70-90%) improves cardiovascular fitness and lactate threshold. Zone 5 (90-100%) is maximum effort, used in short intervals for peak performance gains. Elite athletes spend 70-80% of training time in Zone 2 – the polarized training model. Knowing your zones lets you train smarter, avoid the ‘gray zone’ of medium-hard effort that’s neither restorative nor truly hard.

How to use this tool

1. Enter your age — Used in maximum heart rate formula. Important: age-based formulas have ±10-15 bpm individual variation.
2. Optional: enter resting heart rate — Your morning resting heart rate (before getting out of bed). Used for the Karvonen method which is more personalized than age alone.
3. Select method — Standard (220 – age): widely used. Tanaka (208 – 0.7 × age): more accurate for ages 30+. Karvonen (HR Reserve): uses resting HR, most personalized.
4. Read your zones — 5 zones with target BPM ranges. Zone names indicate the training adaptation each provides.

Heart rate zone formulas

Maximum heart rate (Max HR):

• Standard (Fox 1971): Max HR = 220 – age
• Tanaka (2001): Max HR = 208 – (0.7 × age). More accurate for ages 30+.

Karvonen method (Heart Rate Reserve):

Target HR = Resting HR + (Max HR – Resting HR) × intensity%

HRR (Heart Rate Reserve) = Max HR – Resting HR

This personalizes zones based on YOUR fitness level – someone with a low resting HR (fit) gets higher target zones than someone with high resting HR (less fit) at the same age.

The 5 zones (% of Max HR):

• Zone 1 (Recovery): 50-60%
• Zone 2 (Fat Burn / Aerobic Base): 60-70%
• Zone 3 (Aerobic): 70-80%
• Zone 4 (Anaerobic / Threshold): 80-90%
• Zone 5 (Maximum): 90-100%

Examples

30-year-old male, resting HR 65:

• Max HR (Tanaka): 208 – (0.7 × 30) = 187 bpm
• Zone 1 (50-60%): 94-112 bpm (Karvonen: 126-138 bpm – more personalized)
• Zone 2 (60-70%): 112-131 bpm (Karvonen: 138-150 bpm)
• Zone 3 (70-80%): 131-150 bpm (Karvonen: 150-163 bpm)
• Zone 4 (80-90%): 150-168 bpm
• Zone 5 (90-100%): 168-187 bpm

Tips & best practices

• Spend 80% of training time in Zone 2 – it builds the aerobic foundation that everything else rests on
• Use a chest strap heart rate monitor for accurate readings – wrist-based optical sensors lag and skip during interval changes
• Don’t chase your max HR – it’s the threshold, not a regular target
• Heart rate at given pace decreases as you get fitter – retest max HR every 6 months
• Beta-blockers and some medications artificially lower heart rate – zones don’t apply accurately
• Heat increases heart rate at the same effort – factor in climate when interpreting zones
• Use perceived exertion (RPE 1-10 scale) as a secondary check – HR should match how hard it feels

Limitations & notes

Age-based max HR formulas have ±10-15 bpm variation across individuals. Two 30-year-olds can have actual max HRs of 185 and 200. For accuracy, do a max HR test (medical supervision recommended): all-out 4-minute interval after warmup, or hill repeats to exhaustion. Karvonen method requires accurate resting HR – measure first thing in the morning, lying still, before any stress. Heart medications, stress, illness, dehydration, and heat all affect zones.

Frequently Asked Questions

Is the ‘fat burning zone’ really best for losing weight?

Misleading concept. Zone 2 burns higher PERCENTAGE of fat (vs carbs) per calorie. But higher intensity burns more total calories AND fat. For fat loss, total calorie deficit matters most – any cardio works. Zone 2 is valuable for aerobic base, not specifically for fat burning.

What’s the most accurate way to find my max HR?

Direct measurement is best. Do a graded exercise test (treadmill or bike) under medical supervision to safely reach true max. Self-test: warm up 10-15 min, then do 4-5 minute all-out hill climb or interval to exhaustion – peak HR is your approximate max. Age formulas are starting estimates only.

Why does my watch show different zones than this calculator?

Watches use the same standard formulas but may default to different methods (Garmin allows LTHR-based, Apple uses age-based standard). The ‘right’ zones depend on your training goals – all are reasonable starting points. Personalize by feel and fitness over time.

What is the Karvonen method?

It calculates zones using your Heart Rate Reserve (HRR) = Max HR – Resting HR. Then Target HR = Resting HR + HRR × intensity%. This is more personalized than age-based zones because it accounts for your fitness (lower resting HR = better fit = higher target zones at same effort).

How often should I train in each zone?

Polarized training (popular among endurance athletes): 80% Zone 2, 0% Zone 3, 20% Zones 4-5. Avoid the ‘gray zone’ (Zone 3) which is too hard for recovery and too easy for high-quality intervals. For general fitness: mix all zones, prioritize Zone 2 base building.

My heart rate is high during easy runs – what’s wrong?

Likely ‘aerobic decoupling’ – your fitness isn’t high enough yet to maintain target pace at low heart rate. Slow down, even to walking, to stay in Zone 2. Over weeks, the same Zone 2 effort will produce faster pace. This is the essence of aerobic base building.

Are heart rate zones the same for cycling and running?

Slightly different. Running typically produces higher heart rates than cycling at the same perceived effort (more muscle groups, full body weight). Many athletes have separate cycling vs running zones – cycling zones are typically 5-10 bpm lower for the same effort percentage.

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BMR Calculator · Calorie Calculator · Pace Calculator