Estimate your Basal Metabolic Rate — the energy your body burns at rest — and see how that scales across activity levels.
Basal Metabolic Rate is the energy your body needs just to keep vital organs running — heart, brain, lungs, and the rest — while completely at rest and not digesting food. For most people it accounts for roughly 70% of total daily energy expenditure, with physical activity and digestion making up the rest.
BMR alone isn't how many calories you should eat — it's the baseline your body burns doing nothing. Multiplying it by an activity factor (from 1.2 for sedentary up to 1.9 for extremely active) estimates total daily calories burned, which is what the activity-level table above shows.
They share the same underlying formulas. This page focuses on BMR itself and shows the full range of activity-level outcomes; the Calorie Calculator frames the same numbers around weight maintenance, loss, and gain targets.
Mifflin-St Jeor is the most broadly accurate and is used by default. Katch-McArdle can be more accurate if you know your body fat percentage, since it accounts for lean body mass directly rather than total weight.
Pick another tool to jump straight to it.