Heart Rate Zone Calculator
Training Zones Are Ranges, Not a Single Number
"Get your heart rate up" isn't specific enough to train by. Exercise physiology breaks effort into five zones, each targeting a different physiological adaptation — light recovery work, fat-burning intensity, aerobic conditioning, threshold effort, and maximal output. This calculator computes those five zones using either the Karvonen method, which accounts for resting heart rate, or a simpler percentage-of-max approach.
The Formulas
Both methods start from the same age-based maximum heart rate estimate:
Karvonen Method:
Target HR = ((HRmax − HRrest) × %Intensity) + HRrest
% of Max Method:
Target HR = HRmax × %Intensity
The Karvonen method incorporates heart rate reserve (HRmax minus resting heart rate), which better reflects individual fitness level than the simpler percentage-of-max method, since two people with the same max heart rate can have very different resting rates and cardiovascular fitness.
Where This Calculation Matters
- Structured cardio training — programming easy days, tempo runs, and interval sessions around specific heart rate zones keeps training intensity purposeful rather than arbitrary.
- Fat-burning versus cardio conditioning — Zone 2 is commonly associated with fat oxidation, while Zone 3-4 work builds cardiovascular capacity, and knowing the numeric boundaries makes it possible to actually hit the intended zone.
- Recovery day discipline — keeping easy days genuinely easy (Zone 1-2) is a core principle of most endurance training plans, and it requires knowing where those zones actually sit in bpm.
- Wearable device calibration — many fitness trackers let you input custom zone boundaries rather than relying on generic defaults.
Sample Zones (Karvonen Method, Age 30, Resting HR 60)
Computed directly from the Karvonen formula for a representative case:
| Zone | Intensity | Heart rate range |
|---|---|---|
| Zone 1 – Very Light | 50–60% | 125–138 bpm |
| Zone 2 – Light (Fat Burn) | 60–70% | 138–151 bpm |
| Zone 3 – Moderate (Cardio) | 70–80% | 151–164 bpm |
| Zone 4 – Hard | 80–90% | 164–177 bpm |
| Zone 5 – Maximum | 90–100% | 177–190 bpm |
These zones are specific to this example's age and resting heart rate — use the calculator above with your own numbers for an accurate range.
How to Use This Calculator
- Select a method — Karvonen (uses resting HR) or % of Max Heart Rate.
- Enter your Age.
- For the Karvonen method, also enter your Resting Heart Rate in bpm.
- Select Calculate to see all five training zones in beats per minute.
Related Calculations
To connect these zones to aerobic capacity, see the VO2 Max Calculator. For a heart-rate-based estimate of calories burned during a specific session, check the Exercise Calorie Estimator.