Heart Rate Calculator
Calculate target heart rate zones for optimal cardio training using Karvonen formula. Find fat-burning, aerobic, and anaerobic zones based on age and resting...
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Heart Rate Calculator — Complete Guide
Target heart rate zones, Karvonen formula, VO₂max estimation, training zone science, and resting HR norms.
5
Training heart rate zones
220−Age
Max HR estimate formula
40–100
Normal resting HR (bpm)
60–70%
Fat-burning zone threshold
What Is Target Heart Rate?
Target heart rate (THR) is the range of beats per minute (bpm) that corresponds to a desired exercise intensity. Training within specific heart rate zones allows you to match exercise intensity to fitness goals — whether that is fat burning, aerobic base building, anaerobic threshold training, or peak power development.
Heart rate is a proxy for oxygen consumption and energy expenditure. At higher intensities, the heart beats faster to deliver more oxygenated blood to working muscles. Because the relationship between HR and oxygen consumption (VO₂) is nearly linear between 50–90% of maximum effort, heart rate provides a reliable, real-time indicator of exercise intensity without requiring laboratory equipment.
The American Heart Association (AHA) recommends targeting 50–85% of maximum heart rate for cardiovascular health benefits. The exact zone you train in determines the metabolic fuel used, the physiological adaptations achieved, and the recovery required between sessions.
Maximum Heart Rate Formulas
Max HR = 220 − Age
Examples:
Age 20: Max HR = 200 bpm
Age 30: Max HR = 190 bpm
Age 40: Max HR = 180 bpm
Age 50: Max HR = 170 bpm
Age 60: Max HR = 160 bpm
Age 70: Max HR = 150 bpm
Limitations:
• Standard deviation: ±10–12 bpm
• Underestimates max HR for
fit/athletic older adults
• Original dataset was small and
not peer-reviewed by Fox himself
• Still the most widely used estimate
due to simplicity
Bottom line: reliable for population
averages, not individual prescriptions.The 220−age formula was never derived from a study per se — Fox cited it informally in 1971. Despite this, it remains the clinical standard because it is easy to use and accurate enough for most purposes.
Max HR = 208 − (0.7 × Age) (Tanaka H et al., J Am Coll Cardiol. 2001) Based on 351 studies, 18,712 subjects R² = 0.90 with measured max HR Examples: Age 20: 208 − 14 = 194 bpm Age 30: 208 − 21 = 187 bpm Age 40: 208 − 28 = 180 bpm Age 50: 208 − 35 = 173 bpm Age 60: 208 − 42 = 166 bpm Age 70: 208 − 49 = 159 bpm Advantages: • More accurate than 220−age formula • Based on large diverse meta-analysis • Better for older adults (>40 years) • Lower error at older ages
The Tanaka formula is statistically superior to 220−age and is increasingly recommended in clinical exercise prescription, especially for adults over 40 who are regularly active.
THR = [(MaxHR − RHR) × Intensity%] + RHR Where RHR = Resting Heart Rate Example (30y man, RHR 60, target Zone 3 70%): Max HR = 220 − 30 = 190 bpm HRR = 190 − 60 = 130 bpm THR = (130 × 0.70) + 60 THR = 91 + 60 = 151 bpm Zone 3 range (70–80%): Lower = (130 × 0.70) + 60 = 151 bpm Upper = (130 × 0.80) + 60 = 164 bpm Why Karvonen is superior: Accounts for cardiovascular fitness (lower RHR = larger heart rate reserve) Gives more precise individual targets
The Karvonen formula uses Heart Rate Reserve (HRR = MaxHR − RHR). Athletes with a low resting HR have a larger HRR, meaning their zone targets are at higher absolute bpm — correctly reflecting their fitness.
Simple HR ratio estimate: VO₂max ≈ 15 × (MaxHR ÷ RHR) (Uth 2004 — accurate to ±10%) Example (MaxHR 185, RHR 55): VO₂max ≈ 15 × (185 ÷ 55) VO₂max ≈ 15 × 3.36 VO₂max ≈ 50.5 ml/kg/min VO₂max classifications for men: <35 Poor 35–42 Fair 43–52 Good 53–60 Excellent >60 Superior / Athletic VO₂max classifications for women: <27 Poor 27–35 Fair 36–45 Good 46–53 Excellent >53 Superior / Athletic
VO₂max is the gold standard measure of cardiovascular fitness. This HR-ratio estimate is convenient but laboratory treadmill testing (Bruce protocol) or submaximal tests (Cooper 12-min run) are more accurate.
The 5 Heart Rate Training Zones
| Zone | Name | % Max HR | HR at Age 40 | Primary Fuel | Best For |
|---|---|---|---|---|---|
| 1 | Active Recovery | 50–60% | 90–108 bpm | Fat (>85%) | Recovery, warm-up, beginners |
| 2 | Aerobic Base | 60–70% | 108–126 bpm | Fat (65%) | Endurance, fat loss foundation |
| 3 | Aerobic Endurance | 70–80% | 126–144 bpm | Mixed (50/50) | Cardiovascular fitness building |
| 4 | Threshold / Tempo | 80–90% | 144–162 bpm | Carbs (>65%) | Lactate threshold, race pace |
| 5 | Maximum / VO₂max | 90–100% | 162–180 bpm | Carbs (>85%) | Peak power, HIIT, sports |
Limitations & Safety
Age-predicted maximum heart rate formulas (220−age, Tanaka) are population averages with a standard deviation of roughly ±10–12 bpm — your true maximum heart rate can only be confirmed by a supervised maximal exercise test, not estimated from age alone.
These formulas do not apply reliably to people taking heart-rate-affecting medications (beta blockers, calcium channel blockers) or with a pacemaker — for these groups, perceived exertion (RPE) is a more appropriate intensity guide than a target heart rate zone.
Anyone with a history of heart disease, uncontrolled hypertension, diabetes, or who has been sedentary for an extended period should get medical clearance before starting high-intensity training. Stop exercising immediately and seek medical attention for chest pain, severe shortness of breath, dizziness, or palpitations.
Frequently Asked Questions
What is maximum heart rate (MHR)?▼
Maximum heart rate (MHR) is the highest number of beats per minute (bpm) your heart can achieve during all-out exertion. It decreases with age and varies between individuals. MHR is used to define training intensity zones: exercising at a percentage of your MHR targets specific physiological adaptations. True MHR can only be confirmed by a supervised maximal exercise test.
How accurate is the 220 minus age formula?▼
The formula MHR = 220 − age is a population average with a standard deviation of ±10–12 bpm. This means about two-thirds of people fall within 10–12 bpm of the prediction, but one-third may be further off. A 40-year-old's predicted MHR is 180, but their true MHR could range from ~158 to ~202 bpm. Alternative formulas like Tanaka (MHR = 208 − 0.7 × age) have slightly better accuracy.
What is the Karvonen formula?▼
The Karvonen (Heart Rate Reserve) formula calculates a more personalized target heart rate zone: Target HR = ((MHR − RHR) × %Intensity) + RHR, where RHR = resting heart rate. By incorporating your resting HR, it accounts for cardiovascular fitness. A trained athlete with RHR = 45 bpm has a higher heart rate reserve than an untrained person with RHR = 75 bpm, even if their MHR is similar.
What are the 5 heart rate training zones?▼
Zone 1 (50–60% MHR): Active recovery, low effort. Zone 2 (60–70% MHR): Aerobic base building, fat oxidation, long endurance. Zone 3 (70–80% MHR): Aerobic threshold, tempo runs, improves aerobic capacity. Zone 4 (80–90% MHR): Lactate threshold, race-pace efforts, improves speed. Zone 5 (90–100% MHR): VO2 max training, maximum sprint intervals — used sparingly due to recovery demands.
What is a normal resting heart rate?▼
The American Heart Association defines a normal adult resting heart rate (RHR) as 60–100 bpm measured while sitting quietly. Well-trained endurance athletes often have RHR of 40–60 bpm, a sign of efficient cardiac output. A consistently high RHR (>100 bpm, called tachycardia) or low RHR (<60 bpm with symptoms) should be evaluated by a physician.
Is the fat-burning zone (60–70% MHR) the best for weight loss?▼
The "fat-burning zone" burns a higher percentage of fat as fuel, but lower total calories. Higher-intensity exercise (Zone 4–5) burns far more total calories and more total fat in absolute terms. Research shows that total weekly caloric expenditure — not the percentage of fat burned per session — drives fat loss. Mixing Zone 2 (for volume) and Zone 4–5 (for intensity and caloric expenditure) produces the best results.
How does heart rate relate to VO2 max?▼
VO2 max (maximal oxygen uptake) is the gold-standard measure of aerobic fitness. Heart rate and VO2 maintain a roughly linear relationship during moderate exercise: at approximately 85–90% MHR, most people are at ~100% VO2 max. This relationship allows HR to serve as a practical proxy for exercise intensity. Lactate threshold typically occurs at 80–90% MHR (~75–85% VO2 max).
What is heart rate variability (HRV)?▼
Heart rate variability (HRV) is the beat-to-beat variation in time between heartbeats, measured in milliseconds (ms). High HRV indicates a well-functioning autonomic nervous system and good recovery status. Low HRV can signal overtraining, illness, or stress. HRV is measured at rest (ideally upon waking) and is used by athletes and coaches to optimize training load. Normal HRV ranges are highly individual.
What heart rate is recommended during exercise?▼
The American Heart Association recommends exercising at 50–85% of maximum heart rate for cardiovascular benefit. For general health, 150+ minutes/week of moderate-intensity exercise (50–70% MHR) or 75+ minutes/week of vigorous exercise (70–85% MHR) is advised. Beginners should start at the lower end (50–60% MHR); experienced athletes can work in higher zones for performance gains.
At what heart rate is exercise dangerous?▼
Exercising above 85% MHR is strenuous and should be done in short intervals only by trained individuals. Sustained exercise above 90% MHR carries risk for untrained or at-risk individuals. See a doctor before high-intensity exercise if you have heart disease, hypertension, diabetes, or haven't exercised in years. Warning signs during exercise: chest pain, severe shortness of breath, dizziness, palpitations — stop immediately and seek help.
Do beta blockers affect heart rate calculations?▼
Yes. Beta blockers (metoprolol, atenolol, carvedilol, etc.) reduce maximum heart rate by blocking adrenaline's effect on heart receptors. Patients on beta blockers should not use age-predicted MHR formulas — their true maximum is lower, and training-zone calculations will be inaccurate. The Karvonen formula using monitored RHR still provides relative intensity guidance, but a physician-supervised stress test is the safest approach to establish true HR limits.
References & Clinical Sources
- Tanaka H, et al. Age-predicted maximal heart rate revisited. J Am Coll Cardiol. 2001;37(1):153–6.
- Karvonen J, Vuorimaa T. Heart rate and exercise intensity during sports activities. Sports Med. 1988;5(5):303–11.
- American Heart Association. Target Heart Rates Chart. AHA, 2023.
- Uth N, et al. Estimation of VO2max from the ratio between HRmax and HRrest. Eur J Appl Physiol. 2004;91(1):111–5.
Methodology, sources & limitations
This calculator uses a published formula and the values entered in the calculator to generate the result.
- Formula
- MHR = 220 - age
- Jurisdiction & units
- Intended for US, IN, EU, GB, Global. Supports both units where applicable.
- Assumptions & limitations
- Results are screening or educational estimates based on the inputs you provide. They do not diagnose, treat, or replace advice from a qualified clinician.
- Review status
- Formula and automated QA completed September 9, 2026; independent professional review is pending. Next scheduled review: December 9, 2026.
Validation sources
- AHA Heart Rate Guidelines
- ACSM Exercise Guidelines
Heart Rate Zone Calculator — Answer & Method
Calculate target heart rate zones for exercise using the Karvonen formula.
Formula: Maximum Heart Rate
MHR = 220 - age
Example Calculation
A 30-year-old has a max HR of 190 bpm, with fat burn zone at 60-70% (114-133 bpm).
Important limitation
This is an educational estimate, not a diagnosis or a substitute for professional medical advice.
Key Facts
- The standard formula for maximum heart rate is 220 minus age.
- Fat burning zone is 60-70% of maximum heart rate.