How do you calculate target heart rate?

Using the Karvonen formula: Target HR = (MHR - RHR) × intensity% + RHR, where MHR is maximum heart rate and RHR is resting heart rate. For a person with MHR of 180 and RHR of 60, the 70% training zone is: (180-60) × 0.70 + 60 = 84 + 60 = 144 bpm. Without resting heart rate, the simpler formula is: Target HR = MHR × intensity%. Maximum heart rate is typically estimated as 220 minus age.

What is the fat burning heart rate zone?

Zone 2 (60 to 70% of maximum heart rate) is commonly called the fat burning zone because fat provides the highest proportion of calories at this intensity. However, higher intensity zones burn more total calories per minute, including more absolute fat calories, even though their proportional fat contribution is lower. Zone 2 training is most useful for building aerobic base, improving endurance, and long-duration activities.

What is the Karvonen formula?

The Karvonen formula incorporates resting heart rate into target heart rate calculations: Target HR = (MHR - RHR) × intensity + RHR. This produces a more personalised result than simply multiplying maximum heart rate by a percentage, because two people with different resting heart rates but the same maximum heart rate will have different training zones. A lower resting heart rate (indicating better cardiovascular fitness) results in a higher absolute training zone for the same percentage.

What is a normal resting heart rate?

A typical adult resting heart rate is 50 to 90 bpm. Well-trained endurance athletes often have resting heart rates between 40 and 60 bpm. A resting heart rate above 100 bpm is called tachycardia. Below 40 bpm is bradycardia and should be evaluated by a physician unless the person is a highly trained athlete. Resting heart rate is best measured first thing in the morning before getting out of bed.

Target Heart Rate Calculator

Karvonen formula · 5 training zones · 3 MHR formulas · RPE scale · Step-by-step

Age

Resting Heart Rate (bpm) ?

MHR Estimation Formula

Haskell-Fox: MHR = 220 - age (most common)

❤️ Enter your age (and optionally resting heart rate) to calculate your five personalised training heart rate zones.

Heart Rate Formulas

Maximum Heart Rate Estimation

Maximum heart rate (MHR) is the highest number of beats per minute the heart can achieve during maximal exercise. It is most accurately determined through a graded cardiac stress test, but is commonly estimated using age-based formulas because laboratory testing is impractical for most people.

Haskell-Fox (1971): MHR = 220 - age Most widely used. Convenient but has a standard deviation of ±10-12 bpm. Tanaka, Monahan, Seals (2001): MHR = 208 - (0.7 × age) Based on a meta-analysis of 351 studies. More accurate for older adults. Nes et al. (2013): MHR = 211 - (0.64 × age) Derived from 3,320 healthy adults. Tends to give higher estimates for older ages. Example (age 35): Haskell-Fox: 220-35 = 185 · Tanaka: 208-24.5 = 183.5 · Nes: 211-22.4 = 188.6

Karvonen Formula

The Karvonen formula incorporates resting heart rate to personalise zone calculations:

THR = (MHR - RHR) × intensity% + RHR MHR = maximum heart rate · RHR = resting heart rate HRR = MHR - RHR (heart rate reserve) Example: Age 35, MHR 185, RHR 65 HRR = 185 - 65 = 120 Zone 3 (70-80%): 120×0.70+65=149 to 120×0.80+65=161 bpm

The Five Training Zones

Zone 1

50 to 60%

Recovery

Active recovery, warm-up, cool-down. Very low effort, fully aerobic.

Zone 2

60 to 70%

Aerobic Base

Fat burning, endurance foundation, conversational pace. Sustainable for hours.

Zone 3

70 to 80%

Aerobic

Tempo pace. Improves aerobic capacity and lactate clearance. Somewhat hard.

Zone 4

80 to 90%

Threshold

Lactate threshold. Hard, sustainable 20-40 min. Raises anaerobic threshold.

Zone 5

90 to 100%

VO2max

Maximum effort. Short bursts only. Develops VO2max and speed. Needs full recovery.

ℹ️

Most endurance coaches recommend spending 70 to 80% of weekly training volume in Zones 1 and 2, with the remaining 20 to 30% in Zones 3 through 5. Spending too much time in Zone 3 (sometimes called the "grey zone") accumulates fatigue without producing the adaptations of either low-intensity Zone 2 work or high-intensity Zone 4 to 5 work.

Rating of Perceived Exertion (RPE) Scales

RPE scales allow estimation of exercise intensity without measuring heart rate directly. They are useful when monitoring devices are not available and have been validated in research as reasonable proxies for physiological intensity measures.

Borg Scale (6 to 20)

RPE	Perceived Exertion	~Heart Rate
6	No exertion at all	~60 bpm
7 to 8	Extremely light	~70-80
9 to 10	Very light	~90-100
11 to 12	Light	~110-120
13 to 14	Somewhat hard	~130-140
15 to 16	Hard (heavy)	~150-160
17 to 18	Very hard	~170-180
19	Extremely hard	~190
20	Maximal exertion	Max

The scale is designed so each number × 10 approximates heart rate in a healthy adult. It was developed by Swedish psychologist Gunnar Borg in 1970.

Modified Borg CR10 Scale

RPE	Perceived Exertion	Zone Approx.
0	Nothing at all	Rest
0.5	Very, very weak	Zone 1
1	Very weak	Zone 1
2	Weak (light)	Zone 1-2
3	Moderate	Zone 2
4	Somewhat strong	Zone 2-3
5 to 6	Strong (heavy)	Zone 3-4
7 to 8	Very strong	Zone 4
9	Very, very strong	Zone 4-5
10	Maximal	Zone 5

The CR10 (category ratio) scale uses a 0 to 10 range and is better suited for measuring sensations like pain, breathlessness, and localised muscle fatigue rather than overall exertion.

Target Heart Rate by Age Reference

Age	MHR (Haskell)	Zone 2 (60-70%)	Zone 3 (70-80%)	Zone 4 (80-90%)
20	200	120-140	140-160	160-180
25	195	117-137	137-156	156-176
30	190	114-133	133-152	152-171
35	185	111-130	130-148	148-167
40	180	108-126	126-144	144-162
45	175	105-123	123-140	140-158
50	170	102-119	119-136	136-153
55	165	99-116	116-132	132-149
60	160	96-112	112-128	128-144
65	155	93-109	109-124	124-140
70	150	90-105	105-120	120-135

These ranges use simple % of MHR (no resting heart rate). Add your RHR using the Karvonen formula for more personalised targets.

Frequently Asked Questions

Why does resting heart rate matter for zone calculations?

Resting heart rate reflects cardiovascular fitness. A trained endurance athlete might have a resting heart rate of 45 bpm while a sedentary adult has 75 bpm. Both might have the same maximum heart rate. Without accounting for resting heart rate, their Zone 2 target would be identical. With the Karvonen formula, the athlete's Zone 2 will be a higher absolute bpm because their heart rate reserve (MHR minus RHR) is larger, reflecting their greater cardiovascular capacity.

How accurate is the 220 minus age formula?

The Haskell-Fox formula (220 minus age) has a standard deviation of approximately ±10 to 12 bpm. This means 68% of people fall within ±12 bpm of the estimate. For a 35-year-old, the formula gives 185 bpm, but the actual maximum for two-thirds of 35-year-olds falls between 173 and 197 bpm. The formula is a useful population average but should not be treated as a precise individual measurement. The Tanaka and Nes formulas have somewhat better accuracy, especially for older adults.

What is heart rate reserve and why is it important?

Heart rate reserve (HRR) is the difference between maximum and resting heart rate: HRR = MHR - RHR. It represents the usable range of the heart's capacity above its baseline. A larger HRR generally indicates better cardiovascular fitness. The Karvonen formula uses HRR as the basis for zone calculations, producing zones that are proportional to the functional capacity of the individual's cardiovascular system rather than just their maximum heart rate.

What is the Maffetone Method?

The Maffetone Method, developed by Dr. Phil Maffetone, defines the maximum aerobic heart rate as 180 minus age (with adjustments for health status and training history). Training at or below this ceiling is claimed to build aerobic base without crossing into anaerobic work, promoting fat burning, reducing injury risk, and building sustainable long-term fitness. It is more conservative than most standard Zone 2 targets and is widely used by endurance athletes, triathletes, and ultra-marathon runners.