Heart Rate Zones Calculator: Find Your Max HR and Training Zones
Find your max HR and 5 training zones for cardio workouts
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Reviewed against primary sources.
Fill in the age to see your result.
Age-based max HR formulas have ±10–12 bpm individual variability. People with cardiac conditions, on heart-rate-affecting medications (beta blockers), or starting a new training program should consult a physician for personalized targets.
Heart rate zones are intensity bands defined as percentages of your maximum heart rate (or heart rate reserve in the Karvonen method). The 5-zone system: recovery (50–60%), easy aerobic (60–70%), aerobic (70–80%), threshold (80–90%), and VO2 max (90–100%). Age-based max HR formulas like Tanaka (208 − 0.7×age) estimate max within ±10–12 bpm; for precision, do a measured test.
**A 35-year-old has an estimated max HR of about 184 bpm using the Tanaka formula (208 − 0.7×age).** Zone 2 (easy aerobic) lands at ~110–129 bpm — the 80% of training time most endurance athletes spend. Zone 4 (threshold) is ~147–166 bpm. The age formulas are population averages with ±10–12 bpm variability — for precision, do a measured max HR test or use lab-measured zones from a coach.
What is a heart rate zones?
Use this comprehensive heart rate zones calculator to accurately estimate your maximum heart rate and define the 5 essential training zones crucial for effective cardio programming. Whether you're a beginner building an aerobic base or a seasoned athlete optimizing performance, understanding your zones for recovery, easy, aerobic, threshold, and VO2 max is key. This tool allows you to choose between scientifically validated age-based formulas: Tanaka (208 − 0.7×age) for general use, Gulati for women, or the classic Fox/Haskell (220 − age). You can also input your measured max HR. It supports both the simple-percentage and the advanced Karvonen heart-rate-reserve methods, which accounts for your resting heart rate, making it ideal for trained individuals. All calculations and zone definitions are referenced to the latest ACSM exercise testing guidelines, ensuring reliable and actionable results for running, cycling, and other endurance activities.
The formula
- HR_max — maximum heart rate (estimated or measured)
- HR_rest — resting heart rate, measured first thing in the morning
- intensity — decimal fraction (0.50–1.00) for the target zone
Source: Tanaka et al. (2001) age-predicted max HR; Karvonen heart rate reserve method.
Worked examples
1Average adult, age 35, simple-percentage zones
Tanaka max HR: 208 − 0.7×35 = 183.5, rounded to 184 bpm. Zone 2 (60–70%) = 110–129 bpm. Zone 4 (80–90%) = 147–166. Zone 5 (90–100%) = 166–184. For general fitness, target 150 minutes/week in Zone 2–3 (110–147 bpm), or 75 minutes/week in Zone 4–5 (147+ bpm).
2Trained athlete with low resting HR (Karvonen)
Measured max HR 198, resting HR 45. HR reserve = 153. Karvonen Zone 2 (60–70%) = 45 + 153×0.6 to 45 + 153×0.7 = 137–152 bpm. Simple-percentage Zone 2 would only be 119–139 bpm — about 13 bpm lower. The Karvonen adjustment accurately reflects this athlete's high cardiac efficiency.
3Older woman, age 55, Gulati formula
Gulati max HR: 206 − 0.88×55 = 157.6, rounded to 158 bpm. Zone 2 = 95–111 bpm. Zone 4 = 126–142. Compared to using Tanaka (max 170), Gulati shifts every zone down by ~10 bpm — meaningful for not pushing too hard. For older female athletes, this is the safer default if a measured test isn't available.
How to use this calculator
- Age — Your age in years. The age-based formulas estimate max HR within ±10–12 bpm of measured.
- Resting heart rate (optional) — Measured first thing in the morning before getting up. 60–80 bpm is typical; under 60 suggests above-average aerobic fitness.
- Max HR formula (default: tanaka)
- Measured max HR — Only used if you selected 'I know my measured max HR'. Get this from a graded exercise test or all-out interval session.
- Zone system (default: fiveZone)
- Read the result. Use the worked examples below to sanity-check against a known scenario.
What your result means and what to do next
Most endurance athletes follow an 80/20 polarized training distribution: 80% of weekly training time in Zone 2 (easy aerobic), 20% in Zone 4–5 (threshold and VO2 max). The middle (Zone 3) is the 'gray zone' that produces moderate adaptations across many systems but isn't optimal for any single one. Most recreational runners spend too much time there because it feels productive without being unsustainable.
For general fitness, the WHO and ACSM recommend 150 minutes of moderate-intensity (Zone 2–3) or 75 minutes of vigorous-intensity (Zone 4–5) cardio per week. If you're training for a specific event (5k, marathon, century ride, triathlon), zone distribution shifts based on event duration and individual physiology — work with a coach for periodized planning.
If your real-world workouts feel much harder than your zone calculation suggests, your true max HR is likely 5–15 bpm below the formula. The fix: do a max-HR test (after a thorough warm-up, run 4 minutes at increasing intensity, then 1 minute all-out — peak observed HR is your max). Alternatively, lactate threshold-based zones (set off your 1-hour race-pace HR) are more individually accurate than max-HR-based zones for many trained athletes.
Common mistakes and edge cases
Mistake 1: Relying solely on '220 − age' for max HR
The classic '220 − age' formula (Fox/Haskell) is widely known but highly inaccurate, with an error margin of ±15 bpm. It tends to overestimate max HR for younger individuals and underestimate for older ones. Using this formula can lead to training in zones that are either too easy or dangerously hard, missing the intended physiological adaptations. Always prioritize more accurate formulas like Tanaka or Gulati, or ideally, a measured max HR test.
Mistake 2: Spending too much time in the 'gray zone' (Zone 3)
Many recreational athletes gravitate towards Zone 3 (70–80% max HR) because it feels productive without being overly taxing. However, this 'gray zone' doesn't optimally stimulate either aerobic base development (Zone 2) or high-intensity threshold improvements (Zone 4/5). Elite athletes typically follow an 80/20 polarized training model, spending 80% of their time in Zone 1–2 and 20% in Zone 4–5, minimizing Zone 3 work for superior results.
Mistake 3: Ignoring the impact of medication or health conditions
Heart rate calculations and zones assume a healthy cardiovascular system. Medications like beta-blockers can significantly lower your maximum heart rate (by 20–30 bpm), making standard formulas irrelevant. Conditions like atrial fibrillation or other arrhythmias can also cause heart rate to not accurately reflect effort. Always consult a physician before starting a new exercise program, especially if you have pre-existing conditions or are on medication.
Mistake 4: Not accounting for cardiac drift or environmental factors
During long workouts, especially in hot or humid conditions, your heart rate can gradually rise (cardiac drift) even if your effort level remains constant. This means your perceived zone might be higher than your actual physiological effort. Similarly, dehydration, poor sleep, or illness can elevate resting and exercise heart rates. Be mindful of these factors and adjust your effort or target zones accordingly to stay within your intended training intensity.
Mistake 5: Using wrist-based HR monitors for all training intensities
While convenient for daily tracking and steady-state Zone 2 workouts, optical wrist-based heart rate monitors can be inaccurate during high-intensity intervals, weight training, or in cold weather. They may lag in response or misread by 10–20 bpm, compromising the precision needed for effective zone training. For accurate high-intensity zone work, a chest-strap heart rate monitor (ECG-based) is the gold standard.
How small changes affect your result
On a max HR of 184 (age 35 Tanaka): a 10 bpm error in max HR shifts every zone boundary by ~5–9 bpm. Zone 2 'easy' could be as wide as 110–129 (correct max) or as narrow as 117–137 (max underestimated 10 bpm). For the Karvonen method, a 10 bpm error in resting HR shifts zone boundaries by ~1–2 bpm — much less sensitive. Sensitivity to age is small: 5 years younger or older changes max HR by ~3.5 bpm.
Max HR by formula at age 40
| Formula | Max HR estimate | Notes |
|---|---|---|
| Fox/Haskell (220 − age) | 180 bpm | Most familiar; worst accuracy |
| Tanaka (208 − 0.7×age) | 180 bpm | Best general accuracy ±7 bpm |
| Gulati (women, 206 − 0.88×age) | 171 bpm | Best for women specifically |
| Nes (211 − 0.64×age) | 185 bpm | Norwegian active population |
| Inbar (205.8 − 0.685×age) | 178 bpm | Older but widely cited |
Difference between formulas at age 40 spans 14 bpm — pick one and stick with it for consistency.
Frequently asked questions
What's the most accurate max HR formula?
Should I use simple percentage or Karvonen?
What's Zone 2 and why does it matter?
How do I do a max HR test safely?
Why does my actual HR feel different from the calculated zones?
Is wrist-based HR accurate enough for zone training?
How much time should I spend in each zone?
Should I update my zones as I get fitter?
Heart Rate Zones glossary
How we built this calculator
Methodology
Three formulas are common. Fox/Haskell (220 − age) was published in 1971 from limited data and overestimates max HR for adults under 30 and underestimates for adults over 50. Tanaka (208 − 0.7×age, 2001) is based on a meta-analysis of 18,000+ subjects and is the current consensus. Gulati (206 − 0.88×age, 2010) was specifically derived for women and corrects a systematic underestimate.
This calculator was written by Numora health team and reviewed by ACSM Certified Exercise Physiologist before publication. Both names link to full bios with verifiable credentials.
Sources & references
Every numeric assumption traces to a primary source.
- Tanaka, Monahan, Seals (2001) Age-predicted maximal heart rate revisited, J Am Coll CardiolUSA
- Gulati et al. (2010) Heart rate response to exercise stress testing in asymptomatic women, CirculationUSA
- ACSM Guidelines for Exercise Testing and Prescription, 11th ed.USA
- Karvonen, Kentala, Mustala (1957) The effects of training on heart rateINT
- WHO Physical Activity Guidelines (2020)INT
- USA Triathlon training zones referenceUSA
- Seiler & Tønnessen (2009) Intervals, thresholds, and long slow distance: the role of intensity and duration in endurance trainingINT
- American Heart Association Target Heart RatesUSA
- Numora Editorial Policy. numora.net/editorial-policy
This calculator is for informational purposes only and does not constitute medical advice. Numbers shown are estimates based on the inputs you provide. Conventions and regulations vary by country. Consult a qualified healthcare provider in your country before making decisions based on these results.