Target Heart Rate Calculator Formula
Understand the math behind the target heart rate calculator. Each variable explained with a worked example.
Formulas Used
Target Heart Rate
target_hr = hr_reserve * intensity + resting_hrMax Heart Rate
max_heart_rate = max_hrHeart Rate Reserve
heart_rate_reserve = hr_reserveVariables
| Variable | Description | Default |
|---|---|---|
age | Age(years) | 30 |
resting_hr | Resting Heart Rate(bpm) | 65 |
intensity | Target Intensity | 0.7 |
max_hr | Derived value= 220 - age | calculated |
hr_reserve | Derived value= max_hr - resting_hr | calculated |
How It Works
Karvonen Formula
Target HR = (Max HR - Resting HR) x Intensity% + Resting HR
The Karvonen formula is more accurate than simple percentage methods because it accounts for your resting heart rate (heart rate reserve).
Max HR = 220 - Age
Worked Example
A 30-year-old with a resting HR of 65 bpm targeting 70% intensity.
- 01Max HR = 220 - 30 = 190 bpm
- 02HR Reserve = 190 - 65 = 125 bpm
- 03Target HR = 125 x 0.70 + 65 = 152.5 bpm
Frequently Asked Questions
What is the Karvonen formula?
The Karvonen formula calculates target heart rate using heart rate reserve (the difference between max and resting HR), giving a more personalized target than simple percentage of max HR.
How do I measure resting heart rate?
Measure your pulse first thing in the morning before getting out of bed. Count beats for 60 seconds, or for 15 seconds and multiply by 4.
Learn More
Guide
Heart Rate Zones Explained: Train Smarter with Zone-Based Exercise
Learn about the five heart rate training zones, how to calculate them, and how to use zone-based training to improve endurance, burn fat, and boost performance.
Ready to run the numbers?
Open Target Heart Rate Calculator