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Your five training zones, personalized with resting heart rate.
❤️ Karvonen zones use heart-rate reserve (max − resting), which personalizes intensity far better than raw % of max. Measure resting HR right after waking. Zone 2 builds aerobic base — most training time belongs there.
Zones from raw max-heart-rate percentages treat a trained athlete and a couch-bound beginner identically. The Karvonen method uses heart-rate reserve (max − resting), which widens zones proportionally to fitness.
Measure for a full minute immediately after waking, before coffee or getting up, over several days. Well-trained endurance athletes commonly sit at 40-50 bpm; average adults 60-80.
Max-HR formulas carry ±10-12 bpm individual error. If you have done a hard race or lab test and seen a higher number, use that as your true max instead.
Zone 2 (about 60-70% of reserve) builds mitochondrial density and fat oxidation. Most recreational runners run too hard on easy days — nasal-breathing pace usually lands in Z2.
Disclaimer: This tool is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Results are estimates and should be discussed with a qualified healthcare provider before making health-related decisions.
The Heart Rate Zone Calculator lets you figure out heart rate zone calculatorinstantly, without reaching for a spreadsheet or doing the math by hand. Whether you're planning a budget, checking a loan, or working through homework, the tool applies the correct formula behind the scenes and shows the result the moment you enter your numbers.
Unlike a static chart or table, this calculator adapts to your exact inputs. You can adjust any value and see the outcome update in real time, which makes it easy to compare scenarios — for example, "what if the rate were 1% lower?" or "what if I paid an extra $50 a month?"
Common uses: people reach for this tool when they need to find a zone 2 training heart rate calculator, karvonen formula zones, max hr 220 minus age accurate, or fat burning zone heart rate.
Browser-based tools like this one have a few real advantages over installed software or manual methods:
The Heart Rate Zone Calculator is based on the following formula:
HRmax ≈ 220 − age THR = (HRmax − HRrest) × intensity + HRrest Z1 50-60% · Z2 60-70% · Z3 70-80% · Z4 80-90% · Z5 90-100% of heart-rate reserve
Variables: HRmax = Estimated maximum heart rate (bpm) age = Age (years) HRrest = Resting heart rate (bpm) THR = Target heart rate for a zone (bpm) intensity = Zone fraction of heart-rate reserve, 0.50 to 1.00 HRR = Heart-rate reserve = HRmax − HRrest (bpm)
The Karvonen method measures intensity as a share of your heart-rate reserve — the span from resting to maximum heart rate — so zones shift with your fitness, not just your age. Each zone's bounds come from inserting its percentage into the THR formula.
Worked example: Step 1: Age 40, resting HR 60: HRmax ≈ 220 − 40 = 180 bpm; HRR = 180 − 60 = 120 bpm. Step 2: Zone 2 lower bound: (120 × 0.60) + 60 = 72 + 60 = 132 bpm. Step 3: Zone 2 upper bound: (120 × 0.70) + 60 = 84 + 60 = 144 bpm. Result: Zone 2 (easy aerobic work) is about 132-144 bpm; the Zone 5 ceiling is (120 × 1.00) + 60 = 180 bpm.
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