BMR and Daily Calorie Calculator

Your basal metabolic rate is the energy your body uses at complete rest. Multiply it by how active you are and you get maintenance calories - the amount that keeps your weight steady. Enter your details to find both, and a target for your goal.

The equation uses this only as a constant term; it is not a statement about anyone’s identity.

BMR

1,630

kcal a day at complete rest

Maintenance

2,527

kcal a day to stay the same weight

Your goal

Daily target

2,527kcal

A balanced macro split

30% protein, 40% carbohydrate, 30% fat — one reasonable split among many, not a prescription.

Protein

189g

30%

Carbs

253g

40%

Fat

84g

30%

Mifflin-St Jeor predicts an average for your height, weight, age, and sex. Individual metabolic rates vary by roughly 10% either way, and the activity multiplier is the least precise part of the estimate. Treat the number as a starting point and adjust it against what actually happens on the scale over a few weeks.

BMR, maintenance, and target

Three numbers come out of this calculation and they answer different questions. Basal metabolic rate is what your body burns doing nothing at all. Maintenance is that figure multiplied by how active you are. The target is maintenance adjusted for what you want your weight to do.

Most people who report that a calorie target is not working are comparing against the wrong one of the three, or have overestimated their activity level.

Activity multipliers applied to BMR
LevelMultiplierTypical of
Sedentary1.2Desk work, little or no exercise
Lightly active1.375Light exercise 1-3 days a week
Moderately active1.55Moderate exercise 3-5 days a week
Very active1.725Hard exercise 6-7 days a week
Extremely active1.9Physical job, or training twice a day

The equation

Mifflin-St Jeor predicts resting energy expenditure from weight, height, age, and sex. It replaced Harris-Benedict as the default in dietetic practice because it predicts more accurately across a wider range of body types.

For men the equation is ten times weight in kilograms, plus 6.25 times height in centimetres, minus five times age, plus five. For women the final constant is minus 161 instead of plus five. Nothing else differs.

Setting a deficit that holds

Roughly 7,700 kcal is one kilogram of body fat, so a 500 kcal daily deficit is about half a kilogram a week. Larger deficits lose weight faster in the short term but are harder to sustain and take more lean mass with them.

Floors of about 1,500 kcal for men and 1,200 for women are the usual guidance for adults without medical supervision. This calculator flags a target that falls below them rather than presenting it as a plan.

  • Weight loss is rarely linear week to week; judge over a month.
  • Most people overestimate activity and underestimate intake.
  • Adjust the target against what the scale actually does, not the prediction.
  • The equation is validated for adults, not for children or during pregnancy.

More health tools

Frequently asked questions

BMR is what your body burns at complete rest, keeping your heart, brain, and organs running. Total daily energy expenditure is BMR multiplied by an activity factor, which accounts for movement, exercise, and digesting food. Maintenance calories means TDEE - eat that amount and your weight stays roughly steady.

Mifflin-St Jeor, which predicts resting energy expenditure more accurately than the older Harris-Benedict equation in most populations and is the one dietetic practice guidelines recommend. For men it is 10 times weight in kilograms, plus 6.25 times height in centimetres, minus 5 times age, plus 5; for women the final constant is minus 161 instead.

Roughly 7,700 kcal is one kilogram of body fat, so a 500 kcal daily deficit is about half a kilogram a week. Larger deficits are harder to sustain and risk losing muscle alongside fat. Most adults should not go below about 1,500 kcal for men or 1,200 for women without medical supervision.

The equation predicts an average for your height, weight, age, and sex, and individual metabolic rates vary by around 10% either way. The activity multiplier is the least precise part - most people overestimate how active they are. Use the figure as a starting point and adjust it against what the scale actually does over three to four weeks.

The Mifflin-St Jeor equation applies a different constant term for men and women, reflecting average differences in lean body mass. It is a variable in a formula, not a statement about anyone's identity, and it is the only place the answer depends on it.

No. Mifflin-St Jeor is validated for adults, and the calculator will not accept an age below 15. Children's energy needs are tied to growth and should be assessed against paediatric growth references by a doctor or dietitian.

Start from your maintenance figure - your BMR multiplied by an activity factor - and adjust from there for your goal. There is no single number that applies to everyone of a given height and weight, because activity level changes the answer more than body size does.

This calculator uses the Mifflin-St Jeor equation, which takes weight, height, age, and sex. It is the equation most commonly recommended for general use because it predicts measured resting expenditure more closely than the older Harris-Benedict formula across most populations.