Target Heart Rate Calculator

Q: What is a good target heart rate for fat burning?

Zone 2 (60 to 70% of Heart Rate Reserve using Karvonen) is the fat-burning zone because fat oxidation is highest at moderate intensities. For fat loss, both Zone 2 for long sessions and higher-intensity intervals have a role. Zone 2 is the safer, more sustainable starting point for most adults.

Q: Should I always train within a specific zone?

Not necessarily. A common evidence-supported structure is 80% of weekly volume in Zones 1 to 2 and 20% in Zones 3 to 5. Zones are planning tools, not rigid rules. Deliberate mixing of intensities drives better overall adaptation.

Ethan Caldwell

June 26, 2026

This Target Heart Rate Calculator estimates your personalized training zones using two evidence-based methods: the simple Percentage of MHR method and the more precise Karvonen Formula which accounts for your resting heart rate. Enter your details below to see both side by side.

Target Heart Rate Calculator

Two methods compared: % of MHR vs. Karvonen Formula

Step 1 - Your Basic Info

Age

Used to calculate MHR automatically

Sex

Determines which MHR formula is used

Step 2 - Maximum Heart Rate (MHR)

MHR (bpm)

Auto-filled from age and sex, or enter your measured MHR to override

Measured MHR from a supervised graded exercise test is more accurate than any formula. Override the auto value if you have one.

Step 3 - Resting Heart Rate (for Karvonen method)

Resting HR (bpm)

Measure first thing in the morning before getting out of bed

Average adult resting HR is 60 to 100 bpm. Well-trained athletes often measure 40 to 60 bpm. Average 3 mornings for a reliable reading.

Maximum Heart Rate used

Resting Heart Rate

% of MHR Method

Target = MHR x intensity%

Moderate (60 to 80% MHR)

Simpler method. Does not account for individual fitness level. Can underestimate intensity for very fit individuals and overestimate for deconditioned adults.

Karvonen Formula

Target = RHR + intensity% x (MHR - RHR)

Moderate (60 to 80% HRR)

Uses Heart Rate Reserve (HRR = MHR minus RHR). Personalizes zones by your fitness baseline. Consistently yields more accurate intensity prescriptions.

Zone Visualization (Karvonen)

-- --

Zone % HRR % MHR Karvonen

Zone 1 - Recovery

Warm-up, cool-down, active rest

50 to 60%

Zone 2 - Aerobic Base

Fat burning, endurance, easy run pace

60 to 70%

Zone 3 - Aerobic

Tempo effort, cardiovascular fitness

70 to 80%

Zone 4 - Threshold

Lactate threshold, race pace

80 to 90%

Zone 5 - Maximum

VO2 max intervals, all-out effort

90 to 100%

Note: The Karvonen zones are generally recommended for exercise prescription because they account for individual fitness level through resting heart rate. The % MHR zones are provided for comparison. Always consult a physician before beginning high-intensity exercise, especially if you have any cardiovascular risk factors.

% of MHR vs. Karvonen: What Is the Difference?

Both methods estimate the same target: how hard your heart should be working during a given training session. They differ in what inputs they use and how personalized the result is.

Percentage of MHR

The simplest approach. Multiply your maximum heart rate by the desired intensity percentage. If your MHR is 185 bpm and you want to train at 70%, your target is 130 bpm. No additional inputs needed. The limitation is that it treats two people with the same MHR identically, even if one has a resting heart rate of 45 (very fit) and another has 80 (sedentary) — clearly not the same physiological situation.

Karvonen Formula

The Karvonen method uses Heart Rate Reserve (HRR), which is the difference between your MHR and your resting heart rate. The formula is: Target HR = RHR + (intensity% x HRR). This accounts for your baseline fitness by anchoring the zone calculation at your actual resting rate rather than zero, producing higher, more realistic target zones for fit individuals and lower, safer targets for deconditioned adults.

Which should you use? The Karvonen formula is the standard in clinical exercise physiology and cardiac rehabilitation. For general fitness use, either method is reasonable, but Karvonen produces more personalized zones that tend to feel more accurate during actual training.

How to Measure Your Resting Heart Rate

Resting heart rate (RHR) is one of the most useful single numbers in fitness. A lower RHR generally indicates better cardiovascular efficiency. Here is how to get an accurate reading.

Measure first thing in the morning before getting out of bed, ideally after at least 5 minutes of lying quietly. Count your pulse for 60 seconds (or 30 seconds and multiply by 2). Avoid measuring after caffeine, alcohol, a poor night of sleep, or illness, as all of these temporarily elevate RHR. Take readings on 3 separate mornings and average them for a reliable baseline.

The average adult RHR is 60 to 100 bpm. Trained endurance athletes commonly measure 40 to 60 bpm. Recreational runners and regular exercisers often fall in the 50 to 65 bpm range.

Frequently Asked Questions

What is a good target heart rate for fat burning?

Zone 2 (60 to 70% of HRR using Karvonen, or roughly 60 to 70% MHR) is commonly called the fat-burning zone because fat oxidation is highest at moderate intensities. However, total calorie burn is higher at greater intensities. For fat loss, both Zone 2 for long sessions and higher-intensity intervals have a role. Zone 2 is the safer, more sustainable starting point for most adults.

Why does the Karvonen formula give higher target zones than % of MHR?

Because Karvonen anchors the calculation at your resting heart rate rather than at zero. A person with a resting HR of 60 and MHR of 180 has a Heart Rate Reserve of 120 bpm. Their Karvonen Zone 2 top end is 60 + (0.70 x 120) = 144 bpm. The simple % MHR method would give 180 x 0.70 = 126 bpm. The Karvonen result better reflects the physiological effort at that intensity.

Can I use this calculator if I take beta-blockers or heart medication?

No, not without medical guidance. Beta-blockers and certain other cardiac medications blunt the heart rate response to exercise, meaning standard MHR formulas and zone calculations no longer apply to you. Your cardiologist or exercise physiologist should prescribe zones based on a supervised exercise test that accounts for your medication.

How do I know if I am in the right zone during exercise?

A chest strap heart rate monitor is the most accurate wearable option. Wrist-based optical sensors (smartwatches) are generally accurate at steady-state moderate intensities but can lag or misread during rapid intensity changes. The talk test is a rough guide: Zone 2 you can speak in full sentences, Zone 3 you can speak in short phrases, Zone 4 and above speaking is difficult.

Should I always train within a specific zone?

Not necessarily. Zones are planning and monitoring tools, not rigid rules. Most evidence-supported training programs deliberately mix intensities across a week. A common structure is 80% of weekly volume in Zones 1 to 2 and 20% in Zones 3 to 5. Staying in Zone 2 exclusively is a common beginner mistake that limits top-end development, while too much Zone 4 to 5 increases injury and burnout risk.

References

Karvonen MJ, Kentala E, Mustala O. The effects of training on heart rate: a longitudinal study. Ann Med Exp Biol Fenn. 1957;35(3):307-315. https://pubmed.ncbi.nlm.nih.gov/13470504/
Tanaka H, Monahan KD, Seals DR. Age-predicted maximal heart rate revisited. J Am Coll Cardiol. 2001;37(1):153-156. https://pubmed.ncbi.nlm.nih.gov/11153730/
Gulati M, et al. Exercise capacity and the risk of death in women. Circulation. 2003;108(13):1554-1559. https://pubmed.ncbi.nlm.nih.gov/12975254/
American Heart Association. Target Heart Rates Chart. https://www.heart.org/en/healthy-living/fitness/fitness-basics/target-heart-rates
Seiler S, Tonnessen E. Intervals, thresholds, and long slow distance: the role of intensity and duration in endurance training. Sportscience. 2009;13:32-53.