BMR calculator (Harris-Benedict equation)

What is the Harris-Benedict BMR calculator?

This calculator estimates your basal metabolic rate (BMR) using the revised Harris-Benedict equation. Your BMR is the amount of energy, measured in calories, that your body needs to keep its essential functions running while completely at rest — heartbeat, breathing, temperature regulation, and cell repair.

Enter your sex, age, height, and weight to get your BMR. Choose an activity level and the calculator will also estimate your total daily energy expenditure (TDEE), which is the number of calories you burn across an average day once movement and exercise are added on top of your resting needs.

A short history of the equation

The original equation was published by James Arthur Harris and Francis Gano Benedict in 1919, based on measurements of resting metabolism in healthy adults. It became one of the most widely used tools for estimating energy needs in clinical and dietary settings. In 1984 the coefficients were re-estimated against newer data, producing the revised Harris-Benedict equation used here, which tends to be more accurate for modern populations.

How does the calculator work?

The tool computes BMR in two steps:

1. It selects the formula for your sex and plugs in your weight in kilograms, height in centimeters, and age in years.
2. If you pick an activity level, it multiplies the BMR by the matching activity factor to produce your TDEE.

Heights and weights entered in other units are converted to centimeters and kilograms before the formula is applied.

Activity factors

• Sedentary (little or no exercise): 1.2
• Light exercise (1-3 days per week): 1.375
• Moderate exercise (3-5 days per week): 1.55
• Heavy exercise (6-7 days per week): 1.725
• Extra active (very hard exercise or a physical job): 1.9

Formula

The revised Harris-Benedict equations are:

For men:

$$\text{BMR} = 88.362 + (13.397 \times \text{weight in kg}) + (4.799 \times \text{height in cm}) - (5.677 \times \text{age in years})$$

For women:

$$\text{BMR} = 447.593 + (9.247 \times \text{weight in kg}) + (3.098 \times \text{height in cm}) - (4.330 \times \text{age in years})$$

Total daily energy expenditure then follows from the activity factor:

$$\text{TDEE} = \text{BMR} \times \text{Activity Factor}$$

Examples

Example 1: Sedentary woman

Individual: 30-year-old woman, 60 kg, 165 cm, sedentary.

• Calculate BMR:

$$\text{BMR} = 447.593 + (9.247 \times 60) + (3.098 \times 165) - (4.330 \times 30)$$ $$\text{BMR} = 447.593 + 554.82 + 511.17 - 129.9 = 1383.68$$

• Calculate TDEE (Sedentary factor = 1.2):

$$\text{TDEE} = 1383.68 \times 1.2 = 1660$$

Estimated daily maintenance need: about 1660 calories.

Example 2: Very active man

Individual: 40-year-old man, 80 kg, 180 cm, heavy exercise.

• Calculate BMR:

$$\text{BMR} = 88.362 + (13.397 \times 80) + (4.799 \times 180) - (5.677 \times 40)$$ $$\text{BMR} = 88.362 + 1071.76 + 863.82 - 227.08 = 1796.86$$

• Calculate TDEE (Heavy exercise factor = 1.725):

$$\text{TDEE} = 1796.86 \times 1.725 = 3100$$

Estimated daily maintenance need: about 3100 calories.

Practical notes

• BMR and TDEE are estimates. Real energy needs vary with body composition, genetics, hormones, and health conditions.
• To lose weight, eat below your TDEE; to gain weight, eat above it. A change of roughly 500 calories per day corresponds to about 0.5 kg per week.
• Recalculate when your weight or activity level changes noticeably so the estimate stays useful.
• For medical conditions or specific performance goals, consult a dietitian or physician.

FAQs

What is the difference between BMR and TDEE?

BMR is the energy you burn completely at rest. TDEE is your BMR plus the energy spent on daily movement and exercise, so it is always higher than your BMR.

Why does the men’s formula give a higher BMR?

On average men carry more lean muscle mass, which burns more energy at rest, so the equation assigns them a higher baseline.

How accurate is the Harris-Benedict equation?

It gives a reasonable estimate for most healthy adults. Other equations such as Mifflin-St Jeor may be more accurate for some people, especially those with higher body fat.

Can I use pounds and feet?

Yes. Enter your measurements in any supported unit and the calculator converts them to kilograms and centimeters before applying the formula.

Does a higher BMR mean I am healthier?

Not necessarily. BMR mainly reflects body size, age, sex, and muscle mass. It is a planning number for nutrition, not a direct measure of health. See the related calorie calculator and BMI calculator for more context.