Calorie Calculator

How Daily Calorie Needs Are Calculated

This calculator uses the Mifflin-St Jeor equation — the most validated formula for estimating Basal Metabolic Rate (BMR) in adults. BMR is then multiplied by an activity factor to get TDEE (Total Daily Energy Expenditure) — the actual calories you need each day.

Your goal adjustment is applied on top of TDEE: subtract 500 calories/day for ~1 lb/week weight loss, add 300 calories for lean muscle gain, or eat at TDEE for maintenance.

The Mifflin-St Jeor Equation

Male BMR = 10×weight(kg) + 6.25×height(cm) − 5×age + 5 Female BMR = 10×weight(kg) + 6.25×height(cm) − 5×age − 161 TDEE = BMR × Activity Factor

Activity Multipliers Explained

Level	Multiplier	Description
Sedentary	1.2	Desk job, no intentional exercise
Lightly Active	1.375	Light exercise 1–3 days/week
Moderately Active	1.55	Moderate exercise 3–5 days/week
Very Active	1.725	Hard exercise 6–7 days/week
Extra Active	1.9	Athletes, physical labor, or twice-daily training

Frequently Asked Questions

The Mifflin-St Jeor equation predicts BMR within 10% for most people. The larger source of error is the activity multiplier — people consistently overestimate their activity level. If results don't match your experience, try the next lower activity setting.

A 500-calorie daily deficit produces approximately 1 lb (0.45 kg) of weight loss per week — a sustainable, evidence-based rate. Deficits larger than 1,000 calories/day risk muscle loss and metabolic adaptation. Deficits below 300 calories/day produce slow but very sustainable loss.

BMR (Basal Metabolic Rate) is the calories your body burns at complete rest — just to maintain basic functions. TDEE (Total Daily Energy Expenditure) adds calories burned through all daily activity. TDEE is the number you should base food intake on, not BMR.

For active adults, 1.6–2.2 grams of protein per kilogram of body weight is the evidence-based range for muscle retention and growth. For weight loss specifically, higher protein (2.0–2.4 g/kg) helps preserve muscle mass during a calorie deficit.