Estimate how many calories you need each day to maintain, lose, or gain weight at a chosen rate.
The calculator first estimates your Basal Metabolic Rate (BMR) — the calories your body burns at rest — using one of three formulas, then multiplies it by an activity factor to estimate your total daily maintenance calories. From there, adding or subtracting roughly 500 calories a day corresponds to about 1 pound of weight change per week, since a pound of body weight is roughly 3,500 calories.
Mifflin-St Jeor is generally considered the most accurate for most people and is used by default. The Revised Harris-Benedict equation is an older alternative. Katch-McArdle instead uses your body fat percentage directly, which can be more accurate if you know it — particularly for leaner individuals, since it accounts for lean body mass rather than total weight.
Activity multipliers range from 1.2 (sedentary) to 1.9 (extremely active) — nearly a 60% swing — because exercise is often the single biggest variable in daily energy expenditure, far more than small differences in BMR.
No — every formula here is a population-level estimate. Individual metabolism varies, so treat the result as a starting point and adjust based on your actual weight trend over a few weeks.
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