The Mifflin–St Jeor equation, published in 1990, is widely regarded as one of the most accurate predictive equations for healthy adults and is recommended by many dietetic organisations.
How to use it
Select your sex, enter age, weight and height, then choose the activity level that best describes a typical week. Be honest; most people overestimate activity.
Using the numbers
TDEE is your estimated maintenance intake. A deficit of about 500 kcal per day is a common, moderate starting point for gradual weight loss. Track your weight for two to three weeks and adjust, because every equation has individual error of roughly 10%.
Who should not rely on it
During pregnancy, illness, for children or for anyone with a history of disordered eating, energy needs should be set with a healthcare professional.
Inputs explained
| Field | What to enter |
|---|---|
| Sex | Choose one: Male, Female |
| Age | In years |
| Weight | Units: kg, lb, st, g |
| Height | Units: cm, m, in, ft |
| Activity level | Choose one: Sedentary (little exercise), Light (1–3 days/week), Moderate (3–5 days/week), Very active (6–7 days/week) … |
What each result means
- Basal metabolic rate = 10×[Weight] + 6.25×[Height] – 5×[Age] + [Sex]
- Maintenance calories (TDEE) = [Basal metabolic rate] × [Activity level]
- Mild deficit (≈ −500 kcal) = max([Maintenance calories (TDEE)] – 500, 1200)
Example values
How the main result changes when Age changes and everything else stays at the example values above:
| Age (years) | Basal metabolic rate (kcal/day) |
|---|---|
| 15 | 1,724 |
| 22.5 | 1,686 |
| 30 | 1,649 |
| 37.5 | 1,611 |
| 45 | 1,574 |
| 60 | 1,499 |
Formula
BMR (men) = 10·W + 6.25·H − 5·A + 5BMR (women) = 10·W + 6.25·H − 5·A − 161TDEE = BMR × activity factor (W kg, H cm, A years)Worked example
Man, 30 years, 70 kg, 175 cm, moderately active.
BMR = 10×70 + 6.25×175 − 5×30 + 5 = 700 + 1,093.75 − 150 + 5 = 1,649 kcal/day.
TDEE = 1,648.75 × 1.55 ≈ 2,556 kcal/day.
Key terms
- BMR
- Basal metabolic rate, energy used at complete rest to keep the body functioning.
- TDEE
- Total daily energy expenditure, BMR plus activity and digestion.
- Activity factor
- A multiplier from 1.2 (sedentary) to 1.9 (very hard daily activity).
Frequently asked questions
Is BMR the same as RMR?
They are close. Resting metabolic rate is measured under less strict conditions and is slightly higher.
Why does age reduce BMR?
Muscle mass and organ metabolic rate tend to fall with age.
Which activity level should I choose?
Pick based on total weekly exercise and daily movement; if in doubt, choose the lower one.
What formula does the BMR & Calorie Calculator use?
BMR (men) = 10·W + 6.25·H − 5·A + 5.