The Harris–Benedict equation is a classic formula for calculating the basal metabolic rate (BMR) from sex, weight, height and age. Proposed in 1918–1919, it is still used as a quick way to estimate how many calories the body spends at rest.
Multiplying the result by an activity factor gives total daily energy expenditure — the basis for planning nutrition.
The original formulas (1918–1919)
For men: BMR = 66.47 + 13.75 × weight(kg) + 5.00 × height(cm) − 6.76 × age(years).
For women: BMR = 655.10 + 9.56 × weight(kg) + 1.85 × height(cm) − 4.68 × age(years).
The result is calories per day. The formulas were derived in the early 20th century from indirect-calorimetry data and slightly overestimate BMR in modern people.
The revised version (Roza–Shizgal, 1984)
Refined coefficients. For men: BMR = 88.36 + 13.40 × weight + 4.80 × height − 5.68 × age. For women: BMR = 447.59 + 9.25 × weight + 3.10 × height − 4.33 × age. The accuracy of the estimate is about ±210 kcal/day, so the formula gives a guide, not an absolute value.
Harris–Benedict versus Mifflin–St Jeor
Today many clinicians prefer the Mifflin–St Jeor formula (1990): BMR = 10 × weight + 6.25 × height − 5 × age + 5 (men) or − 161 (women). It is more accurate in overweight people. Both formulas are only an estimate: they do not account for individual metabolism, the share of muscle and thyroid function.
Calculate using this marker
Calculators where Harris–Benedict equation is used directly:
Frequently asked questions
Which formula is more accurate — Harris–Benedict or Mifflin?
In most comparisons the Mifflin–St Jeor formula predicts measured basal metabolic rate more accurately, especially in overweight and obesity. The revised Harris–Benedict is close to it. Both have an error of about 10%, because they do not account for body composition.
Which weight should I use — current or ideal?
To estimate the basal metabolic rate, use actual weight. In marked obesity the formulas may overestimate BMR, so for nutrition planning an adjusted body weight is sometimes used. The most reliable formulas are those that account for lean body mass, such as Katch–McArdle.