Heart Rate Zone Calculator

Calculate your target heart rate zones for optimal cardio training. This tool processes all data locally in your browser. No information is ever sent to any server. Completely free, no registration required.

How to Use the Heart Rate Zone Calculator

1. Enter your input values above
2. Results update automatically
3. Copy or download the output

What is a Heart Rate Zone Calculator?

A Heart Rate Zone Calculator determines your five training zones based on your maximum heart rate (MHR) and resting heart rate, helping you train at the right intensity for your specific fitness goals — whether that's burning fat, building endurance, or improving race performance. Each zone corresponds to a percentage of your maximum heart rate and triggers different physiological adaptations. Training in the wrong zone is one of the most common fitness mistakes: too many people do all their cardio in the 'gray zone' (moderate intensity that's too hard for recovery but too easy for significant improvement).

How Does It Work?

Enter your age and resting heart rate (measured first thing in the morning before getting out of bed). Maximum heart rate is estimated using the formula: 220 − age (or the more accurate Tanaka formula: 208 − 0.7 × age). The calculator then defines five zones: Zone 1 (50-60%: Recovery/easy), Zone 2 (60-70%: Fat burning/aerobic base), Zone 3 (70-80%: Aerobic/cardiovascular improvement), Zone 4 (80-90%: Anaerobic/lactate threshold), and Zone 5 (90-100%: Max effort/sprint). Each zone shows target BPM range, calories burned primarily from fat vs. carbs, and training purpose.

Formula

Max HR (Tanaka) = 208 − (0.7 × age)\nHeart Rate Reserve (HRR) = Max HR − Resting HR\n\nKarvonen Formula: Target HR = (HRR × Intensity%) + Resting HR\n\nZone 1 (Recovery): 50-60% HRR\nZone 2 (Endurance): 60-70% HRR\nZone 3 (Tempo): 70-80% HRR\nZone 4 (Threshold): 80-90% HRR\nZone 5 (VO₂ Max): 90-100% HRR

Who Uses This Tool?

• Runners structuring polarized training (80% easy Zone 2, 20% hard Zones 4-5)
• Weight loss seekers maximizing fat-burning Zone 2 training
• Triathletes and cyclists training for endurance events
• Heart rate monitor users setting custom HR zones on their device
• Fitness beginners learning to exercise at appropriate intensities

Pro Tips

• 80/20 Rule: elite endurance athletes spend ~80% of training time in Zone 1-2 (easy) and only 20% in Zones 3-5 (hard). This builds aerobic base without overtraining
• Zone 2 training ('conversational pace') is your fat-burning sweet spot. You should be able to hold a conversation but feel like you're working. Most people train too hard for this zone
• The 220-age formula is a population average — individual max HR can vary by ±15 bpm. For accuracy, do a field test: after thorough warmup, run all-out for 3 minutes and note peak HR
• Resting heart rate trends are a great fitness indicator. As you get fitter, your resting HR typically decreases. Measure weekly and watch the downward trend

Frequently Asked Questions about Heart Rate Zone Calculator

What's the best heart rate zone for fat burning?

Zone 2 (60-70%) burns the highest percentage of calories from fat (~50-65% from fat). However, higher-intensity zones burn more total calories and more absolute fat calories despite a lower percentage. The best approach: mostly Zone 2 for fat adaptation and base building, with 1-2 higher-intensity sessions per week.

How do I measure my resting heart rate?

Measure first thing in the morning, before getting out of bed, after a good night's sleep. Do this for 3-5 days and average. A normal resting HR is 60-100 bpm; fit individuals often have 40-55 bpm. Avoid measuring after alcohol, poor sleep, or caffeine.

Free online Heart Rate Zone Calculator — no signup, 100% client-side processing. All data stays in your browser.