BCBetter Calculators

Calorie Calculator

Calculate your daily calorie needs (TDEE) based on your age, weight, height, sex, and activity level.

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Enter your values and click Calculate

How It Works

This calculator applies the Mifflin-St Jeor equation, published in 1990 and consistently rated the most accurate BMR formula for non-obese adults in clinical comparisons. The two formulas differ only by the final constant: Male BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5. Female BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161. For imperial inputs, weight converts as: lbs × 0.453592 = kg, and height converts as: total inches × 2.54 = cm. A 30-year-old male at 170 lbs and 5'10" (70 total inches): weight = 77.11 kg, height = 177.8 cm. BMR = (771.1) + (1111.25) − (150) + 5 = 1,737 calories. BMR is then multiplied by an activity factor to produce TDEE: sedentary (×1.2), lightly active (×1.375), moderately active (×1.55), very active (×1.725), super active (×1.9). At lightly active, TDEE = 1,737 × 1.375 ≈ 2,388 calories. The weight loss targets apply a 500 calorie/day deficit (for 1 lb/week) and 250 calorie/day deficit (for 0.5 lb/week), derived from the commonly cited approximation that one pound of body fat contains approximately 3,500 stored calories. Weight gain adds 500 calories above TDEE.

Examples

30-year-old male, 170 lbs, 5'10", lightly active
A common scenario for a moderately active adult male.
Result: TDEE of ~2,450 cal/day to maintain weight.
28-year-old female, 135 lbs, 5'5", moderately active
An active adult female looking to understand her calorie needs.
Result: TDEE of ~2,100 cal/day to maintain weight.
45-year-old male, 200 lbs, 6'0", very active
A heavier, older male with a demanding training schedule — showing how activity level drives calorie needs well above baseline.
Result: TDEE of ~3,157 cal/day to maintain weight; ~2,657 cal/day for 1 lb/week weight loss.

Frequently Asked Questions

What is TDEE?
Total Daily Energy Expenditure (TDEE) is the total number of calories your body burns in a given day, combining your Basal Metabolic Rate — the energy required to sustain basic biological functions at rest — with the calories burned through all physical activity. BMR typically accounts for 60–75% of total daily expenditure, with activity adding the remainder. TDEE is the central number in nutrition planning: consuming fewer calories than your TDEE creates a deficit that leads to weight loss, while consuming more leads to weight gain. Unlike BMR, TDEE changes substantially based on how much you move, making accurate activity level selection the most important input in this calculator.
How many calories do I need to lose weight?
A sustained deficit of 500 calories per day below your TDEE produces approximately one pound of fat loss per week, based on the approximation that one pound of body fat represents roughly 3,500 stored calories. This rate is widely regarded as sustainable and unlikely to cause significant muscle loss or trigger the metabolic adaptations associated with more aggressive restriction. Very low-calorie diets (below 1,200 calories for women or 1,500 for men) can cause fatigue, nutrient deficiencies, and muscle breakdown, and often result in weight regain once normal eating resumes. A moderate deficit sustained consistently over weeks produces better long-term outcomes than crash dieting.
How accurate is the Mifflin-St Jeor equation?
Clinical studies consistently show Mifflin-St Jeor is accurate within 10% of measured resting metabolic rate for most non-obese adults — making it the most reliable of the commonly used prediction equations, including Harris-Benedict and Katch-McArdle. Accuracy decreases at the extremes of body composition: highly muscular individuals tend to have higher actual BMRs than the formula predicts, while individuals with very high body fat percentages often have lower actual BMRs. The activity multipliers introduce additional estimation error, since self-reported activity levels often do not match measured expenditure. Treat the result as a calibrated starting point and adjust intake by 100–200 calories in either direction based on actual weight trend over two to three weeks.

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