BMR Calculator: Resting Energy and Daily Calorie Need

How to use it

Choose your Sex and enter your Age.
Enter your Height in centimetres and your Weight in kilograms.
Choose the Activity level that fits a usual week.
Read the Resting energy and the Daily energy need, then compare the three levels in the table.

How the figures are calculated

Your basal metabolic rate (BMR) is the energy your body uses at rest to keep you alive. The Mifflin-St Jeor equation, published by Mifflin and colleagues in 1990, was built on 498 healthy adults aged 19 to 78 whose energy use was measured in a calorimeter. It is 10 times your weight in kilograms, plus 6.25 times your height in centimetres, minus 5 times your age, plus 5 for men and minus 161 for women.

The revised Harris-Benedict equation (Roza and Shizgal, 1984) updates the 1919 original with different constants for men and women. Mifflin and colleagues found that the 1919 equations overestimated measured energy use by about 5 per cent, so the two formulas can give different answers.

Your daily energy need (TDEE) is the BMR times a physical activity level (PAL). The FAO/WHO/UNU report of 2004 gives PAL ranges: 1.40 to 1.69 for a sedentary or light lifestyle, 1.70 to 1.99 for an active or moderately active one, and 2.00 to 2.40 for a vigorous one. The tool shows each range rather than one number.

These are estimates for information only and are not medical advice. Illness, medicines, pregnancy and very hard training change your needs. Talk to a doctor or dietitian before you change your diet, especially if you have a medical condition or are losing weight without trying.

BMR, men    = 10 x kg + 6.25 x cm - 5 x years + 5
BMR, women  = 10 x kg + 6.25 x cm - 5 x years - 161
TDEE        = BMR x PAL, with PAL from 1.40 to 2.40

Which formula should I read?

Both formulas use only weight, height, age and sex. The Mifflin-St Jeor figure is the one most often recommended for healthy adults, and the page shows the revised Harris-Benedict figure next to it so you can compare.

What this calculator does not include

Body composition: neither equation uses muscle or fat mass, so a very muscular person can need more.
Illness, medicines, pregnancy and breastfeeding, which all change energy needs.
Ages below 19 or above 78: the Mifflin sample covered only those ages.

Worked example: 35-year-old woman, 165 cm, 65 kg

Mifflin-St Jeor: 10 x 65 + 6.25 x 165 - 5 x 35 - 161 = 1,345.25, so the resting energy is 1,345 kcal.

Revised Harris-Benedict: 447.593 + 9.247 x 65 + 3.098 x 165 - 4.330 x 35 = 1,408 kcal.

With an active or moderately active PAL (1.70 to 1.99), the daily energy need is 1,345.25 x 1.70 = 2,287 kcal to 1,345.25 x 1.99 = 2,677 kcal.

Step	Result
Resting energy, Mifflin-St Jeor	1,345 kcal
Resting energy, revised Harris-Benedict	1,408 kcal
Daily energy, active (PAL 1.70 to 1.99)	2,287 - 2,677 kcal

Frequently asked questions

What is the difference between BMR and daily energy need?

BMR is the energy you use at rest. The daily energy need adds the energy of your everyday movement and exercise, so it is the intake that keeps your weight steady.

Which activity level should I choose?

Think of a usual week. If you sit most days, choose sedentary or light; if you exercise regularly, choose active; if you train hard most days or do a heavy physical job, choose vigorous. If you are unsure, compare two levels.

Why is the daily need a range and not one number?

The FAO/WHO/UNU report describes lifestyles as ranges of activity level, because people in the same category differ. A range is more honest than a single figure.

Which formula is more accurate?

Mifflin and colleagues reported that the 1919 Harris-Benedict equations overestimated measured energy use by about 5 per cent. Both formulas are estimates, and a measured value needs a clinic or a specialist laboratory.

Does my resting energy change when I lose weight?

Yes. Both formulas use your weight, so as weight falls the BMR falls too. Recalculate after a large change in weight.

Are the figures I enter sent to a server?

No. The calculation runs in your browser and nothing you enter is sent to us.

Sources

Figures and text last checked on Tuesday, November 10, 2026.

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