Basal Metabolic Rate is the energy your body burns just staying alive: breathing, circulating blood, repairing cells, keeping your organs running, before you've taken a single step. This calculator uses the Mifflin-St Jeor equation, generally considered one of the more accurate resting-metabolism formulas for the general population.
This is your floor. See the TDEE calculator to add activity on top of it.
Reach for BMR when you're building a nutrition plan from scratch and need a true starting point before adding activity on top. It's also useful context if you're curious why two people who look similar can have noticeably different calorie needs at rest — age, sex, height, and weight all shift this number. On its own, BMR isn't a calorie target to eat at; it's the floor you build your actual plan above, which is what the TDEE calculator does next.
The Mifflin-St Jeor equation is: for men, 10 x weight(kg) + 6.25 x height(cm) - 5 x age + 5. For women, the same formula but minus 161 instead of plus 5. It was published in 1990 and has since become one of the most widely recommended resting-metabolism formulas, generally outperforming the older Harris-Benedict equation.
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