Heart Rate Calculator
Our overall fitness calculator computes heart rate instantly. Get accurate stats with historical comparisons and benchmarks.
Formula
THR = ((MaxHR - RestingHR) x Intensity%) + RestingHR
Where THR = Target Heart Rate, MaxHR = Maximum Heart Rate (estimated as 220 - age), RestingHR = Resting Heart Rate measured at rest, and Intensity% = desired training intensity as a decimal. This is the Karvonen formula, which uses Heart Rate Reserve (MaxHR - RestingHR) to provide personalized training targets.
Worked Examples
Example 1: 30-Year-Old Moderate Intensity Training
Problem: A 30-year-old with a resting heart rate of 65 bpm wants to train at 70% intensity. What is their target heart rate?
Solution: Max HR (220 formula) = 220 - 30 = 190 bpm\nHeart Rate Reserve = 190 - 65 = 125 bpm\nTarget HR (Karvonen) = (125 x 0.70) + 65 = 87.5 + 65 = 152.5 bpm\nRounded target HR = 153 bpm
Result: Target Heart Rate: 153 bpm in the Aerobic Zone (Zone 3)
Example 2: 50-Year-Old Heart Rate Zones
Problem: A 50-year-old with a resting heart rate of 72 bpm wants to know their five training zones using the Karvonen method.
Solution: Max HR = 220 - 50 = 170 bpm\nHeart Rate Reserve = 170 - 72 = 98 bpm\nZone 1 (50-60%): (98 x 0.50) + 72 to (98 x 0.60) + 72 = 121 to 131 bpm\nZone 2 (60-70%): 131 to 141 bpm\nZone 3 (70-80%): 141 to 150 bpm\nZone 4 (80-90%): 150 to 160 bpm\nZone 5 (90-100%): 160 to 170 bpm
Result: Five training zones ranging from 121 bpm (Recovery) to 170 bpm (VO2 Max)
Frequently Asked Questions
What is maximum heart rate and why does it matter?
Maximum heart rate (MHR) is the highest number of beats per minute your heart can achieve during maximum physical exertion. It serves as the upper ceiling for all heart rate zone calculations and training intensity prescriptions. The most common estimation formula is 220 minus your age, though newer formulas like Tanaka (208 - 0.7 x age) have been shown to be more accurate in clinical research. Knowing your MHR allows you to set proper training zones, avoid overtraining, and ensure you are working at the right intensity for your fitness goals. Individual variation can be significant, so lab-tested MHR is always more accurate than formula estimates.
How does the Karvonen formula calculate target heart rate?
The Karvonen formula is considered the gold standard for target heart rate calculation because it accounts for your resting heart rate, making it more personalized than simple percentage-of-max methods. The formula is THR = ((MaxHR - RestingHR) x Intensity%) + RestingHR. The difference between your maximum and resting heart rate is called your Heart Rate Reserve (HRR), which represents the actual working range of your heart. A fitter person with a lower resting heart rate will have a larger HRR and therefore different target zones compared to a less fit person of the same age. This method was developed by Finnish physician Martti Karvonen in the 1950s and remains widely used today.
What are the five heart rate training zones?
The five standard heart rate zones each target different physiological adaptations. Zone 1 (50-60% intensity) is the recovery zone used for warm-ups and cool-downs. Zone 2 (60-70%) is the fat-burning zone where your body primarily uses fat for fuel. Zone 3 (70-80%) is the aerobic zone that improves cardiovascular fitness and endurance. Zone 4 (80-90%) is the anaerobic threshold zone where lactate begins to accumulate faster than it can be cleared. Zone 5 (90-100%) is the VO2 max zone used for short, high-intensity intervals. Most training plans recommend spending about 80% of training time in Zones 1-2 and only 20% in Zones 3-5.
What is a healthy resting heart rate?
A normal resting heart rate for adults ranges from 60 to 100 beats per minute, according to the American Heart Association. However, highly trained athletes can have resting heart rates as low as 40 beats per minute because their heart muscle is stronger and more efficient at pumping blood. A lower resting heart rate generally indicates better cardiovascular fitness and more efficient heart function. Factors that can elevate resting heart rate include stress, caffeine consumption, dehydration, lack of sleep, illness, and certain medications. To get an accurate resting heart rate reading, measure it first thing in the morning before getting out of bed, ideally for several consecutive days to find your average.
How does age affect heart rate calculations?
Age is the primary variable in maximum heart rate estimation because the heart naturally loses some of its ability to beat at very high rates as we age. On average, maximum heart rate decreases by roughly one beat per minute per year. This means a 20-year-old has an estimated MHR of 200 bpm while a 60-year-old has an estimated MHR of 160 bpm. However, the rate of decline is not perfectly linear and varies significantly between individuals based on genetics, fitness level, and overall health. This is why the Tanaka formula (208 - 0.7 x age) was developed as an improvement over the traditional 220-minus-age formula, as it was found to be more accurate across a wider age range in research studies.
Can heart rate zones help with weight loss?
Heart rate zones can definitely support weight loss strategies, though the relationship is nuanced. While Zone 2 (60-70% intensity) is often called the fat-burning zone because a higher percentage of calories come from fat at lower intensities, higher-intensity zones burn more total calories per minute. For optimal weight loss, a combination of Zone 2 steady-state cardio and Zone 4-5 interval training is recommended by most exercise physiologists. The afterburn effect (excess post-exercise oxygen consumption or EPOC) is greater after high-intensity work, meaning you continue burning calories for hours after exercise. The best approach is to build an aerobic base with Zone 2 training and incorporate 1-2 high-intensity sessions per week for maximum caloric expenditure.