BMR Calculator | Resting Energy Estimate

This tool applies the Mifflin–St Jeor equation published in 1990. It estimates resting energy expenditure (REE) from age, weight, height and the sex-specific coefficient used in the original study. It does not measure basal metabolic rate (BMR), total daily energy expenditure (TDEE), or a personal calorie requirement.

Resting expenditure is only one part of daily energy use. The equation is useful for comparing assumptions, but its result must not be treated as a minimum amount of food to consume.

For men: REE = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) + 5. For women, use −161 instead of +5. For example, a 30-year-old man at 75 kg and 175 cm gives 1,698.75, rounded to 1,699 kcal/day.

Weight is entered in kilograms and height in centimeters. If you use pounds or inches, the form converts them before applying the equation. The calculation uses the 1990 sex-specific coefficients; it does not use body-fat estimates.

The original study included healthy people aged 19–78. This calculator accepts that age range and finite positive weight and height. The equation was not derived for children or adults over 78, and separate life-stage equations apply during pregnancy and lactation, and it cannot account for individual medical circumstances.

Blocking an unsupported age prevents a numeric output from appearing more certain than the study permits. Pregnancy and lactation have separate energy-requirement models in the National Academies and Health Canada references.

Measured BMR requires controlled basal conditions. Mifflin–St Jeor estimates resting expenditure from a population equation. Total daily expenditure includes activity and other components, which this form cannot measure or separate.

Daily expenditure may include movement, exercise and the energy cost of processing food. The fields in this form cannot assign credible calorie amounts or percentages to those components.

Use the result to learn how the equation responds to inputs and assumptions. It is not a calorie intake target or a predicted rate of weight change. Individual assessment needs context beyond these fields; observed weight trends and professional evaluation may inform intake decisions.

Health Canada notes that relative weight stability or change can help evaluate whether intake meets expenditure. One equation result does not establish that balance, especially during growth or changing health.

Weight, height and age do not capture all influences on resting energy. The 1990 equation was fitted to a study sample, so an individual result may differ from measured expenditure. The selected factor adds another unmeasured assumption.

The original paper studied 498 healthy people and reported a population equation, not a guarantee of accuracy for each individual. Error can arise from both the equation and an assumed activity factor.

Sources: Mifflin et al. (1990), original resting-energy equation; National Academies (2023) and Health Canada, life-stage energy-requirement equations and activity categories. Reviewed 29 September 2026.

• Mifflin et al., 1990
• National Academies, 2023
• Health Canada