This target heart rate calculator builds your five training zones the personalized way — the Karvonen formula, which anchors zones to your heart-rate reserve (max minus resting) instead of raw percentages of max alone.
| Zone | Intensity (HRR) | Heart rate (bpm) | Feels like |
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Zones assume the 220 − age max estimate. A measured max (lab test or hard field effort) beats any formula — enter ages/resting values and treat the output as a starting map, then calibrate against perceived exertion and the talk test.
The Karvonen Formula
Target HR = resting HR + intensity × (max HR − resting HR). The reserve term is the personalization: two 40-year-olds share a 180 max estimate, but resting rates of 50 vs 75 mean their “70% zones” sit 14 bpm apart. Percentage-of-max alone misses that, which is why coaches reach for Karvonen. Max-HR formulas and single-value questions live on our Heart Rate Calculator. Part of our Health Calculators collection.
Worked Example (Verified)
- Age 40, resting 60 (defaults): max ≈ 180, reserve = 120 → 70% target = 60 + 0.7 × 120 = 144 bpm (Zone 3’s floor region)
- Zone 2 (the endurance base everyone undervalues): 132–144 bpm — where most weekly minutes should live for most goals
- The fitter twin: same age, resting 48 → reserve 132, Zone 2 = 127–140 — lower floors at the same relative effort, fitness made visible
- Beta-blockers and some medications cap heart rate directly — formula zones don’t apply; perceived exertion and clinician guidance take over (stated plainly because it matters)
Using Zones Without Worshipping Them
- 220 − age carries ±10–12 bpm of individual error; the Tanaka formula (208 − 0.7 × age) fits population data better and gives 180 at age 40 as well — the agreement ends at other ages (at 60: 160 vs 166).
- Heat, altitude, caffeine, fatigue and cardiac drift move HR at fixed effort by 5–15 bpm across a long session — zones are ranges with judgment applied, not rails.
- The talk test validates cheaply: Zone 2 = full sentences, Zone 4 = phrases, Zone 5 = silence. When watch and body disagree, the body is the primary source.
- Resting HR trends are a recovery instrument: a morning reading 5–10 bpm above baseline flags illness/overtraining before performance does.
Related Tools
- Heart Rate Calculator — max HR and percentage-of-max zones
- VO2 Max Calculator — the aerobic ceiling zones serve
- Health Calculators — the full collection
Frequently Asked Questions
How do I calculate my target heart rate?
Karvonen: target = resting HR + intensity% × (max HR − resting HR), with max ≈ 220 − age. At 40 with resting 60: max 180, reserve 120, so 70% intensity = 60 + 84 = 144 bpm.
What is heart rate reserve?
Max minus resting — the usable range of your heart. It personalizes zones because resting HR reflects fitness: lower resting (bigger reserve) shifts every absolute zone boundary, which fixed percentage-of-max tables ignore.
What zone burns the most fat?
Zone 2 (60–70% HRR) maximizes the proportion of fat in the fuel mix and is sustainable for hours — the base-building zone. Higher zones burn more total calories per minute (more carbs proportionally); total fat loss follows total energy balance, but Zone 2 is where volume, and therefore most fat oxidation over a week, accumulates.
How accurate is 220 − age?
It’s a population average with a standard deviation of about 10–12 bpm — one person in three sits more than 10 bpm from it. Use it to start; a measured max from a graded test supersedes it, and your zones should be rebuilt on the measured number.
Should beginners train in Zone 5?
Rarely and briefly — Zone 5 is for intervals by trained athletes. Beginners build the base in Zones 1–2, touch Zone 3–4 as fitness allows, and get more adaptation per hour there with a fraction of the injury and burnout risk. Clearance from a clinician is the right first step for anyone with cardiac history or risk factors.
Is this target heart rate calculator free?
Yes — free, instant, no sign-up. Training guidance, not medical advice.