Heart Rate Zone Calculator

The Karvonen heart rate formula (Karvonen, Kentala & Mustala, 1957) starts from your heart rate reserve (HRR): max HR minus resting HR. Each zone is then resting HR + zone% × HRR. For example, with a max of 187 and resting 60, HRR is 127, so the top of Zone 2 (70%) is 60 + 0.70 × 127 = 149 bpm. Because it accounts for your resting pulse, Karvonen zones are more personal than plain % of max HR — two 30-year-olds with the same max but different resting HRs get different zones.

The classic Fox formula (220 − age) is from 1971 and is the simplest, but it can miss by 10–15 bpm in either direction. Tanaka (208 − 0.7 × age), published in the Journal of the American College of Cardiology (2001), fits large datasets better and is the best default for most adults. Nes (211 − 0.64 × age) (2013) comes from an even larger cohort. This tool shows all three side by side — and a field-tested max always beats every formula, which is why the calculator lets you enter one.

Dr. Phil Maffetone's 180 formula estimates your maximum aerobic heart rate: 180 − age, adjusted by −10 (illness, surgery, or regular medication), −5 (injured, inconsistent, or frequently sick), +0 (consistent training 2+ years), or +5 (competitive and improving). Your aerobic training zone is then MAF − 10 to MAF. It is deliberately conservative — designed for base building, not racing. This calculator includes the full adjustment questionnaire.

Joe Friel's system, from The Triathlete's Training Bible, is built on lactate threshold heart rate (LTHR) rather than max HR. It uses seven zones — Z1 through Z4 plus Z5a (super-threshold), Z5b (aerobic capacity) and Z5c (anaerobic capacity) — with slightly different boundaries for running vs cycling (cycling zones start lower: 81% vs 85% of LTHR for Zone 1). This calculator renders the complete Friel 7-zone table for your sport.

LTHR (lactate threshold heart rate) is the highest heart rate you can sustain for about an hour — the most personal anchor for training zones. Joe Friel's field test: warm up 10–15 minutes, then go as hard as you can sustain for 30 minutes; your average heart rate over the last 20 minutes is approximately your LTHR. It is cheaper than a lab test and safer than an all-out max-HR test, and you can enter the result directly in this calculator.

Ranked by how personal they are: tested LTHR (Friel) is the gold standard for athletes, then Karvonen (uses your resting HR), then % of max HR (simplest, least personal). Maffetone answers a different question — your aerobic ceiling for base training. So if you're asking "what should my heart rate zones be", the honest answer is: start with Karvonen from a tested max, upgrade to a tested LTHR when you can, and check the agreement table above — the bpm range where all methods overlap. Where they disagree, trust a tested LTHR over any formula.

Zone 2 (roughly 60–70% of heart rate reserve) is easy aerobic work — you can hold a conversation. It gets attention because fat oxidation peaks as a percentage of fuel here and it drives mitochondrial and capillary adaptations with low injury risk. Most endurance coaches suggest the bulk of weekly volume — often cited as 150+ minutes — sits in Zone 2, with 1–2 harder sessions on top. This calculator gives you your exact Zone 2 range under every method.

The formulas themselves don't take gender as an input — max-HR estimators use age, Karvonen uses resting HR, and LTHR/Friel/Maffetone use tested values. Individual variation within each gender is far larger than the average difference between genders. Whether you want a heart rate zone calculator for women or for men, the method is identical: use a tested max HR or LTHR rather than a population formula, and re-test as fitness changes.

Yes — maximum heart rate declines roughly 0.7–1 bpm per year, so your zones drift downward over time. Re-run the calculator whenever your age changes the estimate materially, and re-test your max HR or LTHR every 6–12 months, or after a long break, illness, or a big fitness jump. Resting HR also tends to fall as fitness improves, which shifts Karvonen zones upward relative to %MHR zones.

Yes — and reusing running zones on the bike or in the pool is one of the most common mistakes. LTHR typically sits 5–10 bpm lower in cycling than running (less muscle mass, seated position) and lower still in swimming (horizontal body position, water pressure, cooling). That's why this calculator has sport presets: different Friel boundaries and a different LTHR estimate per sport. Ideally, test LTHR separately in each sport.

Use the watch-ready copy button: it formats your chosen method and sport as plain text (e.g. "Z2 Aerobic base: 136–149 bpm") for pasting into notes or a spreadsheet. In Garmin Connect, go to your user profile → heart rate zones and switch the basis to "%HRR" or "%LTHR" to match the method you picked; Apple Watch uses % of max HR by default; Zwift takes custom zones under settings; Coros, Strava and Peloton all accept manual zone entry. Make sure the basis (%MHR, %HRR, or LTHR) matches, or the numbers won't line up.

Zone 2 burns the highest percentage of calories from fat, which is where the "fat burn zone" label comes from. But harder zones burn more total calories per minute — including more total fat. For fat loss, total training volume plus diet matter far more than which zone you pick. Zone 2's real advantage is that you can accumulate a lot of it without breaking down, which is why it anchors base-building plans rather than weight-loss shortcuts.

Yes. Beta blockers blunt the heart-rate response to exercise, so formula-based zones (and even a tested max) won't reflect your true effort — zones calculated here can be misleading or unsafe to chase. Some other cardiac and blood-pressure medications have similar effects. If you take heart medication, talk to your doctor about how to gauge exercise intensity (many clinicians suggest RPE — perceived effort — instead), and treat this calculator as educational only.

Max HR barely moves with training, so retesting yearly (or after the number stops matching how efforts feel) is enough. LTHR moves with fitness — retest every 8–12 weeks during structured training, after illness or a long break, and whenever threshold workouts start feeling mislabeled (too easy or impossibly hard). Also retest if you change sports, since LTHR is sport-specific.

On the Borg CR10 scale: Z1 ≈ 1–2 (very light), Z2 ≈ 3–4 (light), Z3 ≈ 5–6 (moderate), Z4 ≈ 7–8 (hard), Z5 ≈ 9–10 (maximal). The classic talk test mirrors it: full conversation in Z1–Z2, broken sentences in Z3, short phrases in Z4, and no talking in Z5. RPE is a useful cross-check — if your monitor says Zone 2 but you can barely speak, trust your body and check your max-HR/LTHR inputs.

No. This is an educational training tool, not medical advice. Heart-rate formulas are population estimates and can be off by 10–15 bpm; they don't account for heart conditions, medications (especially beta blockers), or other health factors. See a doctor before vigorous exercise if you have a heart condition, chest pain, dizziness, very high blood pressure, or you're starting intense training after a long sedentary period. Stop exercising and seek care if you feel chest pain, faint, or unusually breathless.