AI Health Assistant
BetaAsk questions about your calculation results
3 free questions per session
AI provides general information, not medical advice. Always consult a healthcare professional.
About This Calculator
Training at the right heart rate intensity maximizes the benefits of cardiovascular exercise while minimizing overexertion risk. This calculator uses the Karvonen method with your age and resting heart rate to define personalized heart rate zones for fat burning, aerobic conditioning, and peak performance. Exercising within your target zone ensures you're working hard enough to improve fitness without pushing into dangerous territory.
Quick Tips
- 1 Use the talk test — you should struggle to hold conversation at 80% max.
- 2 Resting heart rate measured first thing in the morning is most accurate.
- 3 Beta blockers and caffeine both significantly alter target heart rate zones.
Example Calculation
A 42-year-old with resting heart rate of 68 bpm (Karvonen method).
Max HR: 178 bpm | Moderate zone (50-70%): 123-145 bpm | Vigorous (70-85%): 145-161 bpm
Understanding Heart Rate Zones
Heart rate zones divide your exercise intensity into five ranges based on percentage of maximum heart rate. Zone 1 (50-60%) is recovery, Zone 2 (60-70%) is fat burning, Zone 3 (70-80%) is aerobic endurance, Zone 4 (80-90%) is anaerobic threshold, and Zone 5 (90-100%) is maximum effort. Each zone produces different training adaptations.
The Karvonen Formula
This calculator uses the Karvonen formula, which accounts for your resting heart rate: Target HR = ((Max HR - Resting HR) × Intensity%) + Resting HR. This is more accurate than simply multiplying max heart rate by a percentage because it personalizes the zones based on your current fitness level.
Benefits of Zone Training
Training in specific heart rate zones allows you to target specific fitness adaptations. Zone 2 training builds aerobic base and burns fat efficiently. Zone 3 improves cardiovascular fitness. Zone 4 increases lactate threshold and speed. Most training plans recommend spending 80% of training time in Zones 1-2 and 20% in Zones 3-5.
Measuring Your Heart Rate
Measure resting heart rate first thing in the morning before getting out of bed. Count your pulse for 60 seconds or use a fitness tracker. During exercise, chest strap monitors are most accurate, followed by optical wrist sensors. Average resting heart rate for adults is 60-100 bpm, with fitter individuals typically having lower rates.
Frequently Asked Questions
Maximum heart rate is estimated as 220 minus your age. This is a population average — individual maximum heart rate can vary by 10-15 beats per minute. The only way to determine your true max heart rate is through a supervised maximal exercise test.
Zone 2 (60-70% max HR) burns the highest percentage of calories from fat. However, higher-intensity zones burn more total calories per minute. For overall fat loss, total calorie burn matters most. A mix of Zone 2 and higher-intensity intervals is most effective.
Generally, yes. A lower resting heart rate indicates a more efficient heart. Well-trained athletes may have resting heart rates of 40-60 bpm. An average adult resting heart rate is 60-100 bpm. A resting heart rate consistently above 100 bpm should be discussed with a doctor.
The 220-minus-age formula has a standard deviation of about 10-12 bpm, meaning your actual max heart rate could be significantly higher or lower than predicted. It is a useful starting point but should not be treated as exact. Adjust zones based on your perceived exertion during workouts.