Your BMR (basal metabolic rate) is the number of calories your body burns per day at complete rest — powering breathing, circulation, and cell repair. This calculator uses the Mifflin-St Jeor equation, the resting-energy formula most nutrition professionals prefer for healthy adults. BMR is the floor of your energy budget: multiply it by an activity factor to estimate total daily burn (TDEE).
Suppose you put the default values into BMR Calculator:
Plug those into the formula M: 10·kg + 6.25·cm − 5·age + 5 and the result is:
The defaults — male, 32, 5 ft 10 in, 168 lb — convert to 177.8 cm and about 76.2 kg. That gives 10 x 76.2 + 6.25 x 177.8 - 5 x 32 + 5, which is roughly 762 + 1,111 - 160 + 5 = 1,718 kcal per day. Spread out, that is about 72 kcal per hour just to keep the lights on, or roughly 12,028 kcal per week before counting any movement or exercise.
| Term | Men | Women |
|---|---|---|
| Weight | +10 x kg | +10 x kg |
| Height | +6.25 x cm | +6.25 x cm |
| Age | -5 x years | -5 x years |
| Constant | +5 | -161 |
Mifflin et al., 1990 · Source: Mifflin-St Jeor equation
The calculator uses the Mifflin-St Jeor equation, published in 1990 from resting-energy measurements by indirect calorimetry and widely adopted as a more accurate replacement for the older Harris-Benedict formula. The equation is 10 x weight in kg + 6.25 x height in cm - 5 x age, plus 5 for males or minus 161 for females. US units are converted first (feet and inches to cm at 2.54 cm per inch, lbs to kg at 0.45359). It deliberately excludes activity, the thermic effect of food, and body composition — a very muscular person burns more at rest than the equation predicts, because lean mass is not an input.
References: Mifflin-St Jeor equation.
Last reviewed July 2, 2026 · Editorial policy