Max heart rate
172bpm
Tanaka
220 − age
169bpm
classic
Zone 2
103–121bpm
aerobic base
Vigorous from
133bpm
about 77% of max
Show the math
Max HR = 208 − 0.7 × 51 = 172 bpm
Heart rate zones at 51
| Zone | BPM | % of max | Feels like |
|---|---|---|---|
| Zone 1 · Recovery | 86–103 | 50–60% | Easy, conversational |
| Zone 2 · Aerobic base | 103–121 | 60–70% | Steady, can still talk |
| Zone 3 · Tempo | 121–138 | 70–80% | Comfortably hard |
| Zone 4 · Threshold | 138–155 | 80–90% | Hard, short phrases |
| Zone 5 · Max effort | 155–172 | 90–100% | All-out, seconds to minutes |
Karvonen zones by resting heart rate
| Resting HR | Zone 1 | Zone 2 | Zone 3 | Zone 4 |
|---|---|---|---|---|
| Resting 55 | 114–125 | 125–137 | 137–149 | 149–161 |
| Resting 65 | 119–129 | 129–140 | 140–151 | 151–162 |
| Resting 75 | 124–133 | 133–143 | 143–153 | 153–163 |
Karvonen: resting + (max − resting) × intensity. More personal if you know your resting rate.
How to use it
- Enter your numbers. Switch between US and metric units at any time.
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These are estimates, not a diagnosis. A clinician can account for your health history and medicines.
Other ages
Common questions
What is a good heart rate zone for a 51-year-old?
Zone 2, about 103 to 121 bpm, builds aerobic base. Moderate exercise sits around 110 to 131 bpm.
What is the max heart rate at 51?
About 172 bpm by the Tanaka formula, or 169 by 220 minus age. Individual max can differ by 10 or more beats.