BMR Chart by Age and Weight

Basal metabolic rate is the calories your body burns keeping you alive at rest — heart, brain, kidneys, breathing, temperature — and it accounts for roughly 60 to 70 percent of most people's total daily energy use. It is the largest and most predictable part of your calorie needs, which is why almost every calorie target starts here.

Both tables use the Mifflin-St Jeor equation, published in 1990 and still the formula most dietetic guidance recommends for healthy adults. Because BMR depends on height as well as weight and age, each table is calculated at a fixed reference height — 178 cm for men and 164 cm for women — and the height adjustment table further down lets you correct for your own.

Comparing the two tables at the same weight and age shows a gap of about 166 calories a day. That is not a biological mystery: the Mifflin-St Jeor equation is identical for both sexes except for a constant, which is +5 for men and −161 for women. The formula treats sex as a flat offset rather than something that scales with body size, so the difference is the same at 50 kg as at 110 kg.

Height enters the equation at 6.25 calories per centimetre, so correcting the tables above for your own height is straightforward arithmetic. Find the row closest to your difference from the reference height and apply the adjustment.

A worked example. A 40-year-old woman weighing 70 kg reads 1,364 calories from the women's table. If she is 174 cm rather than 164 cm, that is 10 cm taller, so she adds 63 calories for an estimated BMR of about 1,427 calories a day. The BMR calculator does the same arithmetic for any exact combination, and also shows the Harris-Benedict estimate alongside it for comparison.

Reading across and down the grid exposes the size of each factor, which is more useful than any single cell:

• Body weight is worth 10 calories per kilogram. Ten kilograms of body weight moves BMR by 100 calories a day, which is why a larger person genuinely does need more food at rest — and why losing weight lowers your calorie needs as you go, a large part of why weight loss slows down.
• Age costs 5 calories per year. Over the 50-year span of these tables that is 250 calories a day, all else equal. Real-world losses are usually larger, because muscle mass and daily activity also tend to fall with age, and neither is in this equation.
• Height is worth 6.25 calories per centimetre. Being 10 cm taller adds about as much as being 6 kg heavier.
• Sex is a flat 166 calories. A constant, not a proportion — the equation makes no allowance for differences in body composition beyond that offset.

Mifflin-St Jeor was derived by regression on 498 healthy adults. It predicts a group average well and an individual less well: the original validation work put roughly 70 percent of people within 10 percent of their measured resting energy expenditure, which at a BMR of 1,600 calories is a band of about 320 calories wide. Two specific groups should treat the tables with more caution than that.

• Very lean or very muscular people. The equation has no body-composition term, so it under-predicts for people carrying well above average muscle and over-predicts at very high body fat. If you know your body fat percentage, the Katch-McArdle equation — which works from lean mass instead — usually fits better.
• People at the edges of the source sample. The tables extend to 110 kg and age 70 because the arithmetic permits it, not because the formula was validated across that whole range. Treat the extreme corners as rough.

BMR is also not a calorie target. It is what you would burn lying still all day, so eating at your BMR is a substantial deficit for anyone who moves. To turn it into maintenance calories, multiply by an activity factor — the maintenance calories chart does exactly that for every BMR in these tables, and our BMR guide walks through the whole calculation once by hand.