The Karvonen Method: Heart Rate Reserve Explained
The Karvonen method calculates heart rate training targets from your heart rate reserve (HRR) — the range between your resting and maximum heart rate. Published by Finnish physician Martti Karvonen and colleagues in 1957, it differs from the simple percentage-of-max-HR method because it incorporates your resting heart rate. Use the calculator below to see your own HRR, zones and target heart rate.
Key Takeaways
🧮 Don't know your resting HR yet? Our general heart rate zone calculator works from age alone using the %Max HR method.
Karvonen Heart Rate Reserve Calculator
Enter your age and resting heart rate. Results update as you type.
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The Karvonen Formula: Step by Step
The Karvonen formula uses a concept called Heart Rate Reserve (HRR) — the difference between your maximum and resting heart rates. This reserve represents the range your heart can operate within, and training zones are calculated as percentages of this reserve added back to resting heart rate.
The Formula:
Step 1: Heart Rate Reserve = Max HR − Resting HR
Step 2: Target HR = Resting HR + (Intensity % × HRR)
Intensity % refers to the lower or upper bound of the zone (e.g., 60% for lower Zone 2, 70% for upper Zone 2).
Zone Intensity Percentages Used on This Site
The Karvonen formula is the method; this five-zone 50–100% HRR framework is SnapHRZones' display convention. Other exercise-intensity classifications use different HRR ranges. For the two hardest zones, see high-intensity heart-rate zones.
Worked Example (Fixed Values)
Example only — not your result. Zone 2 using the Karvonen method for a 40-year-old man with a resting HR of 58 bpm:
Step-by-Step Example
Max HR (Tanaka formula): 208 − 0.7 × 40 = 180 bpm
Heart Rate Reserve: 180 − 58 = 122 bpm
Zone 2 lower bound (60%): 58 + (0.60 × 122) = 58 + 73.2 = 131 bpm
Zone 2 upper bound (70%): 58 + (0.70 × 122) = 58 + 85.4 = 143 bpm
Karvonen Zone 2: 131–143 bpm
Compare to standard method (60–70% of 180): 108–126 bpm.
For this person the two methods give different ranges (131–143 vs 108–126 bpm) because the Karvonen calculation adds resting heart rate back on top of a percentage of the reserve, while %Max HR does not use resting heart rate at all.
Why Resting Heart Rate Matters
Resting heart rate is the second input the Karvonen formula needs. It is influenced by training, genetics, age, sleep, stress, hydration and medication, so it is useful context but not a definitive fitness measure on its own.
What Resting HR Reflects
- • Training status (among other factors)
- • Autonomic nervous system balance
- • Recovery state (rising HR = fatigue/stress)
- • Long-term training adaptations
Typical Resting HR by Group
- • Elite endurance athletes: 35–55 bpm
- • Recreational athletes: 50–65 bpm
- • Average adults: 60–80 bpm
- • Sedentary individuals: 75–100 bpm
- • Above 100 bpm: discuss with a healthcare professional
How to Measure Resting Heart Rate Accurately
- 1. Measure first thing in the morning, before getting out of bed
- 2. Lie still for 5 minutes after waking
- 3. Count heartbeats for 60 seconds (or 30 sec × 2)
- 4. Repeat for 3–5 consecutive mornings
- 5. Use the average, excluding any outlier days (illness, poor sleep, alcohol)
Your resting HR can change significantly over weeks of training. Changes can reflect training, but also sleep, stress or illness. When using the Karvonen method, update your resting HR measurement every 4–8 weeks.
When the Karvonen Method Makes a Difference
The two methods diverge most when resting heart rate differs from average. Situations where this matters:
Low resting HR
A 45-year-old with a resting HR of 45 bpm gets different Karvonen targets than a 45-year-old with the same max HR and a resting HR of 75 bpm, because the reserve is larger.
Standard zones feel off
If %Max HR zones feel unusually easy or hard, comparing them with HRR-based targets from the same inputs can be informative. Perceived effort and the talk test remain useful cross-checks.
Using a measured max HR
Any error in an age-estimated max HR carries into both methods. If you have a measured max HR, enter it in the calculator instead of the estimate.
Tracking resting HR over time
If your resting HR changes, your Karvonen targets change. Recalculate with an up-to-date, averaged resting HR.
Karvonen vs Standard Method: Side-by-Side
| Feature | Standard (% Max HR) | Karvonen (% HRR) |
|---|---|---|
| Inputs needed | Age only | Age + resting HR |
| Uses resting HR | No | Yes |
| Simplicity | Very simple | Slightly more complex |
| Practical requirement | Age (or measured max HR) | Reliable resting HR measurement |
| Changes when resting HR changes | No | Yes |
These are different ways of translating relative intensity into heart-rate targets. The HRR method includes resting heart rate; the %Max HR method does not. Both rely on a max HR value, which is an estimate unless measured.
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Frequently Asked Questions
Disclaimer: This calculator is for informational purposes only and does not provide medical advice. Always consult with a healthcare professional before starting any new exercise program.
Content Reviewed for Accuracy
Content based on peer-reviewed exercise physiology research.
- • Karvonen, M.J., Kentala, E. & Mustala, O. (1957). The effects of training on heart rate. Annales Medicinae Experimentalis et Biologiae Fenniae, 35(3), 307–315.
- • Swain, D.P. & Leutholtz, B.C. (1997). Heart rate reserve is equivalent to %VO2 reserve, not to %VO2max. Medicine & Science in Sports & Exercise, 29(3), 410–414.