Calorie Calculator

How this works

This calculator uses the Mifflin-St Jeor equation to estimate your BMR — the calories your body burns at rest — then multiplies it by an activity factor to get your TDEE, a realistic estimate of your full daily burn. From there, choosing a goal simply adds or subtracts a daily calorie amount sized to a weekly rate of weight change, and the macro section splits that target into grams of protein, carbs, and fat so you have a number to actually plan meals around, not just a single calorie figure.

FAQ

What's the difference between BMR and TDEE?

BMR (Basal Metabolic Rate) is roughly how many calories your body burns at complete rest just to keep you alive — breathing, circulation, cell repair. TDEE (Total Daily Energy Expenditure) adds your activity level on top of that, so it's a realistic estimate of how many calories you actually burn in a normal day. TDEE is the number to compare against your food intake, not BMR.

Why does it ask for biological sex?

The formula used here (Mifflin-St Jeor) includes a fixed offset that accounts for the average difference in muscle mass and body composition between men and women at the same weight and height, since muscle burns more calories at rest than fat does. It's a population-average adjustment for the equation, not a statement about anyone's identity.

How is the calorie target for losing or gaining weight calculated?

It applies a daily surplus or deficit to your maintenance number, based on the rule of thumb that roughly 7,700 kcal (about 3,500 kcal per pound) corresponds to 1 kg of body fat. A 500 kcal/day deficit works out to roughly 0.5 kg (1 lb) lost per week; a 250 kcal/day deficit to roughly half that. The same math applies in reverse for gaining weight.

How accurate is this?

Reasonably close for most people, but it's still a population-average formula — actual metabolism varies with genetics, muscle mass, hormones, and health conditions, easily by 10% or more in either direction. Use the number as a starting point, track your actual weight trend over 2-3 weeks, and adjust up or down based on what really happens.

How are the suggested macros calculated?

Each preset splits your target calories into percentages for carbs, protein, and fat, then converts those to grams using 4 calories per gram of carbs and protein, and 9 calories per gram of fat. "Balanced" is a general-purpose 40/30/30 split; the other presets shift more of the total toward protein or fat. These are common starting splits, not a personalized nutrition plan.