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Heart Rate Zone Calculator
Estimate your max HR with the research-validated Tanaka formula (208 − 0.7 × age) — more accurate than the age-biased 220 − age — then get five training zones with %HRmax and Karvonen (%HRR) shown side by side (~20 bpm apart, the #1 zone error) and Zone 2 highlighted. A fitness estimate (±10–12 bpm); a lab test or wearable is most accurate. Accurate, instant and free — for United States.
What these mean:
What these mean:
Estimated max HR ≈ 180 bpm via Tanaka (208 − 0.7 × age) at age 40. Zone 2 (aerobic base, 60–70% of max) ≈ 108–126 bpm by %HRmax, or 132–144 bpm by Karvonen %HRR (resting HR 60). An estimate — age-predicted max HR varies ±10–12 bpm; a lab/field test or wearable is most accurate. General fitness guidance.
Max HR (bpm)
180 bpm
Zone 2 low (bpm)
108 bpm
Zone 2 high (bpm)
126 bpm
| Zone | % of max | %HRmax (bpm) | %HRR / Karvonen (bpm) |
|---|---|---|---|
| Zone 1 | 50–60% | 90–108 bpm | 120–132 bpm |
| Zone 2aerobic base | 60–70% | 108–126 bpm | 132–144 bpm |
| Zone 3 | 70–80% | 126–144 bpm | 144–156 bpm |
| Zone 4 | 80–90% | 144–162 bpm | 156–168 bpm |
| Zone 5 | 90–100% | 162–180 bpm | 168–180 bpm |
Tanaka vs 220 − age at your age
%HRmax vs %HRR (Karvonen) — don’t conflate them
An estimate — general fitness guidance
How we calculate this
Reviewed by Reckonist Editorial · Last reviewed July 2026. Figures follow the methods and sources set out in our editorial standards.
Max HR via Tanaka (208 − 0.7 × age); zones by %HRmax and Karvonen %HRR. An estimate (±10–12 bpm) — general fitness guidance.
Tanaka 2001 · Karvonen
Pair your zones with training: set your pace with the Running Pace Calculator, and estimate the energy cost with the Calories-Burned Calculator.
Accurate max HR, then two ways to zone it
Heart-rate zones start from your maximum heart rate. Most calculators still use the stale 220 − age; this one defaults to Tanaka (208 − 0.7 × age), the research-validated equation. From max HR it derives five zones two ways — %HRmax and Karvonen (%HRR), which uses your resting HR — and shows both side by side. Every value carries its unit (bpm).
Max HR — Tanaka default
vs legacy 220 − age
maxHR = 208 − 0.7 × age · legacy: 220 − age
Tanaka is more accurate across ages. 220 − age is age-biased — too low for older adults, too high for the young; the two cross near age 40.
Zones — %HRmax and Karvonen
%HRR uses resting HR
%HRmax = maxHR × p · Karvonen = ((maxHR − restHR) × p) + restHR
The same zone % gives different bpm — often ~20 bpm apart in the mid-zones. Karvonen is more personalised; showing both is the fix for the #1 zone error.
- 1Max HR: 208 − 0.7 × 40 = 208 − 28 = 180 bpm (220 − age also gives 180 here — the equations cross near age 40).
- 2Zone 2 by %HRmax (60–70%): 0.6 × 180 = 108, 0.7 × 180 = 126 → 108–126 bpm.
- 3Zone 2 by Karvonen (HRR = 180 − 60 = 120): 0.6 × 120 + 60 = 132, 0.7 × 120 + 60 = 144 → 132–144 bpm — about 24 bpm higher than %HRmax.
Tanaka vs 220 − age — why the default matters
The old 220 − age is convenient but age-biased. Compared with Tanaka it underestimates max HR in older adults — about 10 bpm low by age 70 — and modestly overestimates it in the young, crossing over near age 40. At age 60, Tanaka gives 166 bpm versus 220 − age at 160 bpm; that 6 bpm shifts every zone downward if you use the legacy equation. This calculator defaults to Tanaka and offers 220 − age only with that caveat attached.
The crossover is near age 40
%HRmax vs %HRR (Karvonen) — the ~20 bpm gap
The single biggest heart-rate-zone error is treating %HRmax and %HRR (Karvonen) as the same thing. They are not: %HRmax takes a flat percentage of max HR, while Karvonen works from your heart-rate reserve (max − resting) and adds resting HR back in. Because of that, Karvonen zones sit higher — for a 40-year-old with a resting HR of 60, the same Zone 2 is 108–126 bpm by %HRmax but 132–144 bpm by Karvonen. This tool shows both columns so you can see the difference and pick the method your plan uses.
Which should I use?
The five zones — and why Zone 2 is having a moment
The five zones are Zone 1 (50–60%), Zone 2 (60–70%), Zone 3 (70–80%), Zone 4 (80–90%) and Zone 5 (90–100%) of max. Zone 2— the aerobic base zone — is the one behind the “Zone 2 training” trend: easy, conversational-pace endurance work that builds your aerobic engine. It’s highlighted in the results table.
An estimate — general fitness guidance
Frequently asked questions
First estimate your maximum heart rate from your age, then take percentages of it for each zone. This calculator defaults to the Tanaka formula (max HR = 208 − 0.7 × age), which is more accurate than the old 220 − age. The five zones are 50–60% (Zone 1), 60–70% (Zone 2), 70–80% (Zone 3), 80–90% (Zone 4) and 90–100% (Zone 5) of max. If you enter your resting heart rate, it also shows Karvonen (%HRR) zones, which are more personalised. For a 40-year-old, max HR ≈ 180 bpm and Zone 2 is about 108–126 bpm by %HRmax.
Tanaka (208 − 0.7 × age) is the research-validated equation, from a 2001 meta-analysis of 351 studies. The classic 220 − age is age-biased: it underestimates max HR in older adults (about 10 bpm low by age 70) and overestimates it in younger people, with the two crossing near age 40. At age 60, Tanaka gives 166 bpm versus 220 − age at 160 — a 6 bpm gap that shifts every zone. This tool defaults to Tanaka and flags 220 − age as the legacy option.
Zone 2 is 60–70% of your maximum heart rate — the aerobic base zone behind the "Zone 2 training" trend. For a 40-year-old with a max HR of 180, Zone 2 is about 108–126 bpm by %HRmax. If you use the Karvonen (%HRR) method with a resting HR of 60, the same Zone 2 works out to roughly 132–144 bpm. That ~20 bpm difference is exactly why this calculator shows both methods side by side.
The %HRmax method takes a percentage of your max HR directly (zone = maxHR × %). The Karvonen method uses your heart-rate reserve — the gap between max and resting HR — as target = ((maxHR − restHR) × %) + restHR. Because Karvonen adds your resting HR back in, its zones sit higher: for the same "Zone 2, 60–70%", %HRmax gives 108–126 bpm while Karvonen gives 132–144 bpm for a 40-year-old with a resting HR of 60. Conflating the two is the most common heart-rate-zone mistake; Karvonen is the more personalised of the two.
Only for the Karvonen (%HRR) zones. Without a resting HR, the calculator still gives you the %HRmax zones, which need only your age. If you want the more personalised Karvonen zones, measure your resting HR first thing in the morning before getting up, and enter it — the tool then shows both methods side by side.
They are an estimate. Any age-predicted maximum heart rate carries individual variation of about ±10–12 bpm, so two people the same age can have genuinely different maxes. A lab test (graded exercise test) or a good field test is the most accurate way to find your true max HR, and a chest-strap or wrist wearable can track your zones during exercise. Treat these numbers as general fitness guidance and a starting point, not hard limits.
Method, formulas & references
Methodology: max HR estimated via Tanaka (208 − 0.7 × age; legacy 220 − age offered but flagged as age-biased). Zones: %HRmax = maxHR × p, and Karvonen (%HRR) = ((maxHR − restHR) × p) + restHR — the two differ ~20 bpm for the same zone %. Five zones: Z1 50–60 · Z2 60–70 · Z3 70–80 · Z4 80–90 · Z5 90–100%. All calculations run client-side and nothing is stored. A fitness estimate — age-predicted max HR varies ±10–12 bpm; a lab/field test or wearable is most accurate. General fitness guidance.
Cross-links
How we calculate this
Reviewed by Reckonist Editorial · Last reviewed July 2026. Figures follow the methods and sources set out in our editorial standards.
Max HR is estimated with Tanaka (208 − 0.7 × age); zones by %HRmax and Karvonen (%HRR). This is a general fitness estimate — age-predicted max HR varies ±10–12 bpm, and a lab/field test or wearable is most accurate. General fitness guidance.
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