Heart Rate Reserve Calculator
Karvonen zones from resting and max heart rate.
Enter your values
ⓘ Live results
Results
- Heart rate reserve
- 130 bpm
- Zone 2 (aerobic base)
- 136-149 bpm
- Zone 4 (threshold)
- 162-175 bpm
- Zone 5 (VO2 max)
- 175-188 bpm
| Zone | Intensity | Range |
|---|---|---|
| 1 Recovery | 50-60% | 123-136 |
| 2 Aerobic | 60-70% | 136-149 |
| 3 Tempo | 70-80% | 149-162 |
| 4 Threshold | 80-90% | 162-175 |
| 5 Max | 90-100% | 175-188 |
Quick answer
Heart rate reserve is max minus resting heart rate; Karvonen zones apply an intensity percentage to that reserve.
target = resting + intensity x (max - resting)
How to use the Heart Rate Reserve Calculator
- 1Measure resting heart rate first thing in the morning for three days.
- 2Use a tested max heart rate if you have one, or 208 - 0.7 x age.
- 3Spend most training time in zone 2.
Worked example
Using the values the calculator loads with:
Inputs
- Resting heart rate58 bpm
- Max heart rate188 bpm
Results
- Heart rate reserve130 bpm
- Zone 2 (aerobic base)136-149 bpm
- Zone 4 (threshold)162-175 bpm
- Zone 5 (VO2 max)175-188 bpm
Frequently asked questions
Why Karvonen over percent of max?
It accounts for your resting heart rate, giving zones that fit your fitness, not an average.
How do I find true max?
A supervised ramp test or an all-out hill effort at the end of a hard session.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.