How do I calculate my heart rate zones?

Use the Karvonen formula: target HR = (HRR × intensity%) + resting HR, where HRR = max HR − resting HR. For example, a 30-year-old with a 65 bpm resting HR and a 190 bpm max has HRR = 125, so Zone 2 (60–70%) = (125 × 0.60–0.70) + 65 = 140–153 bpm. This calculator does the math for all five zones automatically when you enter age, resting HR, and a formula.

What is heart rate reserve (HRR)?

Heart rate reserve is the difference between your maximum heart rate and your resting heart rate — it represents the usable working range of your cardiovascular system. HRR is the foundation of the Karvonen method because it accounts for individual fitness: two runners with the same max HR but different resting HRs end up with different absolute bpm values for the same relative effort.

Which max HR formula is most accurate?

For the general population, Tanaka et al. (2001) tends to be more accurate than the older Haskell & Fox 220 − age formula, especially for adults over 40. Nes et al. (2013) performs well across the full age range. Any age-based formula has a standard deviation of roughly ±10–12 bpm — a graded exercise test or field test (if medically cleared) is the only way to know your true max. Use the Custom option if you have a tested value.

What heart rate zone burns the most fat?

Zone 2 (60–70% HRR) has the highest proportion of fat oxidation relative to carbohydrate — often 50–70% of calories from fat. However, higher zones burn more total calories per minute, and total fat burned depends on duration plus intensity together. For weight management, the best zone is the one you can sustain long enough to accumulate meaningful volume — for most recreational runners that is Zone 2.

How do I find my true max heart rate?

The gold standard is a maximal graded exercise test in a lab with ECG monitoring and a physician present. Field tests exist (e.g., repeated 3-minute all-out uphill efforts after a thorough warm-up) but should only be attempted by trained, medically cleared runners. For everyone else, a formula estimate is safer and good enough — errors of ±5–10 bpm rarely shift zones in ways that meaningfully change training.

What is a normal resting heart rate?

The American Heart Association lists 60–100 bpm as normal for adults. Trained runners often sit at 40–60 bpm, and highly trained endurance athletes sometimes drop to the low 30s (Miguel Indurain was famously measured at 28). A chronic RHR above 100 bpm or a sudden 5–10 bpm increase over a few days without other explanation is worth discussing with a doctor.

Should I train by heart rate or by perceived effort?

Use both. Heart rate is objective but lags behind effort changes by 30–60 seconds and can drift upward (cardiac drift) in heat or late in long runs. Rating of perceived exertion (RPE, 1–10 scale) is immediate but subjective. Experienced runners cross-check: if HR says Zone 2 but RPE says Zone 3, the body is telling you something — slow down or cut the session short.

Why do my heart rate zones feel wrong?

Most commonly, the age-based max HR estimate is off by 10–15 bpm, which shifts all zones. Try a different formula (Tanaka for adults 40+, Nes for a broad cohort), or use a field-tested max via the Custom option. Other common causes: stale resting HR (recheck every 8–12 weeks as fitness improves), caffeine or dehydration inflating HR, or an optical wrist sensor misreading during the first few minutes of a run.

Heart Rate Zone Calculator

Karvonen-method heart rate zones using your age, resting HR, and four research-backed max HR formulas.

Age

Your current age. Used to estimate max heart rate if you don't know your actual max.

Resting Heart Rate

Your resting heart rate in beats per minute. Measure first thing in the morning before getting out of bed, for 60 seconds.

Max HR Formula

Max Heart Rate

190bpm

Heart rate reserve 125 bpm

Heart Rate Zones

50–60% HRR
Recovery
128–140BPM
Active recovery — easy conversation pace for recovery runs.
60–70% HRR
Aerobic Base
140–153BPM
Fat oxidation and endurance — long runs and easy runs.
70–80% HRR
Tempo
153–165BPM
Aerobic capacity — comfortable steady-state running.
80–90% HRR
Threshold
165–178BPM
Lactate clearance — tempo runs and cruise intervals.
90–100% HRR
VO2max
178–190BPM
Maximal oxygen uptake — interval training at hard effort.

Heart-rate zones are estimates only. Consult a qualified medical professional before starting or changing any training program, especially if you have a heart condition, are pregnant, or take medication that affects heart rate.

Calculate your personal heart-rate training zones using the Karvonen heart-rate-reserve method, with four research-backed max HR formulas and running-workout context for every zone. Enter your age, your resting heart rate measured first thing in the morning, and pick a max HR formula — Haskell & Fox (1970), Tanaka et al. (2001), Inbar et al. (1994), Nes et al. (2013), or your own tested max. The calculator returns your max heart rate, your heart-rate reserve (HRR = max − resting), and five precise training zones from Recovery (50–60% HRR) through VO2max (90–100% HRR), each with a bpm range and the running workouts it fits. Training zones change with fitness: as your resting HR drops, your zones widen — recalculate every few months.

HRR = HRmax − HRrest    ·    target_HR = (HRR × intensity%) + HRrest

HRR: = Heart rate reserve — the working range between resting and max
HRmax: = Maximum heart rate, measured or estimated from age
HRrest: = Resting heart rate in bpm, measured first thing in the morning
intensity%: = Decimal percentage of HRR for the target zone (e.g., 0.70 for 70%)
target_HR: = The bpm value to train at for the chosen intensity

Worked example — age 30, resting HR 65, Haskell & Fox

HRmax = 220 − 30 = 190 bpm
HRrest = 65 bpm
HRR = 190 − 65 = 125 bpm
Zone 2 low = (125 × 0.60) + 65 = 75 + 65 = 140 bpm
Zone 2 high = (125 × 0.70) + 65 = 87.5 + 65 = 153 bpm
→ Train Zone 2 (aerobic base) at 140–153 bpm
= Zone 2 (aerobic base) = 140–153 bpm for a 30-year-old with a 65 bpm resting HR

Formula F10 from site/03-globals.md §formulas. Published by Martti Karvonen (1957) and adopted by ACSM. Karvonen is preferred over straight %HRmax because it accounts for individual resting HR — a fit runner with a 45 bpm resting HR and a non-runner with a 75 bpm resting HR reach very different absolute bpm values for the same relative effort.

Five max-HR formulas offered in this calculator, with source year and best-fit population. A tested max from a graded exercise test is always more accurate than any formula.
Formula	Equation	Source	Year	Best for
Haskell & Fox	220 − age	Haskell & Fox	1970	General default, universal recognition
Tanaka	208 − 0.7 × age	Tanaka, Monahan & Seals	2001	Adults 40+ — meta-analysis of 351 studies
Inbar	205.8 − 0.685 × age	Inbar et al.	1994	Trained individuals across age ranges
Nes	211 − 0.64 × age	Nes et al., HUNT study (n=3,320)	2013	Healthy adults across the full age spectrum
Custom	tested max (user input)	Graded exercise test / field test	—	Runners with a measured max HR

Zone 1 — Recovery · 50–60% HRR

Active recovery between hard sessions. Breathing is conversational, pace is easy. Examples: shakeout runs the day after a workout, warm-ups, cool-downs. Typical use: 10–20% of weekly mileage.

Zone 2 — Aerobic Base · 60–70% HRR

Fat-oxidation zone and endurance foundation. You can hold a full conversation. Examples: the bulk of easy runs, long Sunday runs. Typical use: 70–80% of weekly mileage for most endurance runners.

Zone 3 — Tempo · 70–80% HRR

Aerobic capacity and steady-state work. Comfortably hard; breathing is rhythmic but speech is limited to short sentences. Examples: progression runs, steady 30–40 minute efforts. Typical use: 5–10% of weekly mileage.

Zone 4 — Threshold · 80–90% HRR

Lactate-clearance zone, roughly 1-hour race pace. You can manage a few words at a time. Examples: tempo runs, cruise intervals (e.g., 4 × 1 mi at threshold). Typical use: 1–2 quality sessions per week.

Zone 5 — VO2max · 90–100% HRR

Maximal oxygen uptake, hard interval work. Speech is essentially impossible. Examples: 3–5 min repeats at 3K–5K pace (e.g., 5 × 1000 m, 4 × 4 min). Typical use: one session every 7–10 days with full recovery.

Two ways to anchor effort

Heart rate

Objective measurement of internal load, read in real time from a chest strap or optical wrist sensor
Self-adjusts for heat, humidity, altitude, sleep debt, and cumulative fatigue
Lags effort changes by 30–60 seconds (cardiac drift) — not ideal for short intervals
Requires reliable measurement — wrist optical sensors can misread during the first few minutes of a run
Best for: long runs, tempo work, recovery runs, hot-weather pacing

Use HR when external conditions vary or when dialling in aerobic base volume

Pace

Objective external output, read from GPS every second with no lag
Fixed target — does not adapt to heat, trail gradients, or a bad night's sleep
Instant feedback — ideal for VO2max repeats and threshold intervals
Requires accurate distance measurement — GPS error on urban trails can exceed 10%
Best for: short intervals, goal-race pacing on flat terrain, workouts with paced targets

Use pace for intervals and goal-race execution; use HR for everything else

Finding Your Resting Heart Rate

A reliable resting HR is the foundation of the Karvonen method. Four simple steps keep your zones anchored to reality.

Measure first thing in the morning
Before getting out of bed, before caffeine, ideally on a rest day or easy day. Lie still for two minutes, then measure for a full 60 seconds. Morning readings are the most repeatable.
Use a two-finger pulse check or a chest strap
Place index and middle fingers on the radial artery (wrist, thumb side) or carotid artery (side of neck, below the jaw). Count for 60 seconds — short counts multiplied by a factor amplify measurement error. Chest straps are more accurate than optical wrist sensors at rest.
Repeat across 5–7 mornings and average
RHR varies 5–15 bpm day to day based on stress, hydration, and prior training load. Average 5–7 consecutive mornings to get a stable baseline. Discard any day after hard intervals, late caffeine, or a poor night's sleep.
Recheck every 8–12 weeks
RHR drops as aerobic fitness improves — trained distance runners typically sit at 40–55 bpm, elite endurance athletes often 30–45 bpm. Update your RHR in this calculator every couple of months; stale RHR values widen zones artificially and push you too hard.

Resting HR (bpm) by age × self-reported fitness level. Based on AHA adult norms (60–100 bpm normal range) with runner-specific strata from Cooper Institute and Norwegian HUNT cohort data. Lower is typically better, but extreme lows can also indicate overtraining.
Age group	Athlete	Excellent	Good	Average	Below average
18–25	49–55	56–61	62–65	66–69	70+
26–35	49–54	55–61	62–65	66–70	71+
36–45	50–56	57–62	63–66	67–70	71+
46–55	50–57	58–63	64–67	68–71	72+
56–65	51–56	57–61	62–67	68–71	72+
65+	50–55	56–61	62–65	66–69	70+

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Sources

1.Karvonen, M. J., Kentala, E., & Mustala, O. — The effects of training on heart rate: a longitudinal study — Annales Medicinae Experimentalis et Biologiae Fenniae, 35(3), 307–315, 1957 (accessed 2026-04-22)
2.Tanaka, H., Monahan, K. D., & Seals, D. R. — Age-predicted maximal heart rate revisited — Journal of the American College of Cardiology, 37(1), 153–156, 2001 (accessed 2026-04-22)
3.Nes, B. M. et al. — Age-predicted maximal heart rate in healthy subjects: The HUNT Fitness Study — Scandinavian Journal of Medicine & Science in Sports, 23(6), 697–704, 2013 (accessed 2026-04-22)
4.Inbar, O. et al. — Normal cardiopulmonary responses during incremental exercise — Medicine & Science in Sports & Exercise, 26(5), 538–546, 1994 (accessed 2026-04-22)
5.ACSM's Guidelines for Exercise Testing and Prescription, 11th ed. — American College of Sports Medicine, 2021 (accessed 2026-04-22)
6.Target Heart Rates Chart — American Heart Association (accessed 2026-04-22)

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