BMR & Calorie Calculator
Estimate your basal metabolic rate and total daily calories from weight, height, age, sex, and activity.
Energy your body burns at complete rest, before any activity.
Estimated daily calories to maintain your current weight at this activity level.
A 25-year-old man weighing 70 kg at 175 cm has a basal metabolic rate of about 1,674 kcal/day by the Mifflin–St Jeor equation: 10·70 + 6.25·175 − 5·25 + 5 = 1,673.75. Multiplying by a sedentary activity factor of 1.2 gives a total daily energy need (TDEE) of roughly 2,009 kcal/day to maintain weight.
BMR vs. TDEE
Your basal metabolic rate (BMR) is the energy your body uses at complete rest just to stay alive — breathing, circulation, and keeping cells running. It is the calories you would burn lying still all day, eating nothing. Your total daily energy expenditure (TDEE) is BMR plus everything you actually do: walking, working, exercise, and digesting food. TDEE is the number most people care about, because eating at your TDEE keeps your weight roughly steady.
This calculator estimates BMR with the Mifflin–St Jeor equation — the most accurate of the common predictive formulas for the general population — then scales it by an activity factor to reach TDEE.
Mifflin–St Jeor equation. TDEE = BMR × activity factor (1.2 to 1.9).
Worked example: 70 kg, 175 cm, 25-year-old man, sedentary
Plug the values into Mifflin–St Jeor, then apply the sedentary activity factor:
- 1 Convert units if needed. Use weight in kilograms and height in centimetres. 1 lb ≈ 0.4536 kg; 1 in = 2.54 cm.
- 2 Pick the sex constant. Add 5 for men or subtract 161 for women at the end of the equation.
- 3 Compute BMR. 10·70 + 6.25·175 − 5·25 + 5 = 700 + 1,093.75 − 125 + 5 = 1,673.75 ≈ 1,674 kcal/day.
- 4 Choose an activity factor. Sedentary = 1.2 for someone with little or no exercise.
- 5 Multiply to get TDEE. 1,673.75 × 1.2 ≈ 2,009 kcal/day — the calories to maintain weight.
Activity multipliers
Multiply BMR by the factor that best matches a typical week to estimate TDEE.
| Activity level | Typical week | Factor | TDEE (BMR 1,674) |
|---|---|---|---|
| Sedentary | Little or no exercise | 1.2 | ≈ 2,009 kcal |
| Light | Exercise 1–3 days | 1.375 | ≈ 2,301 kcal |
| Moderate | Exercise 3–5 days | 1.55 | ≈ 2,594 kcal |
| Active | Exercise 6–7 days | 1.725 | ≈ 2,887 kcal |
| Very active | Hard exercise or physical job | 1.9 | ≈ 3,180 kcal |
Using the estimate for weight change
TDEE is the maintenance number. To lose weight you eat below it (a calorie deficit); to gain you eat above it (a surplus). Body fat stores roughly 7,700 kcal per kilogram, so a steady deficit of about 500 kcal/day works out to a little under half a kilogram per week. The arithmetic is simple, but the body is not: predicted calories are an estimate only. Real needs vary with muscle mass, genetics, hormones, sleep, and how accurately you log food, and the body adapts as weight changes. Treat the number as a starting point, then adjust based on what the scale actually does over a few weeks.
This tool is for general information, not medical advice. Talk to a qualified professional before making significant dietary changes.