Calorie Calculator
Find daily calories for weight loss, maintenance, or gain.
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How This Calorie Calculator Works
This calculator uses established scientific formulas validated in peer-reviewed literature. All calculations run locally in your browser — no data is sent to any server.
Activity Level Multipliers
| Level | Multiplier | Description |
|---|---|---|
| Sedentary | 1.200 | Little or no exercise, desk job |
| Lightly Active | 1.375 | Light exercise 1-3 days/week |
| Moderately Active | 1.550 | Moderate exercise 3-5 days/week |
| Very Active | 1.725 | Hard exercise 6-7 days/week |
| Extremely Active | 1.900 | Very hard exercise, physical job |
The Mifflin-St Jeor Equation
This calculator uses the Mifflin-St Jeor equation (1990), which the American Dietetic Association identified as the most accurate predictive equation for estimating resting energy expenditure in healthy individuals. The equation accounts for gender, age, height, and weight.
Men: BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age) + 5
Women: BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age) - 161
The BMR is then multiplied by an activity factor (see table above) to estimate Total Daily Energy Expenditure (TDEE). For a more detailed breakdown, use our dedicated TDEE Calculator or check your resting metabolic rate with the BMR Calculator.
Safe Rate of Weight Change
For weight loss, a deficit of 500 calories per day produces approximately 1 pound of fat loss per week. This is considered the maximum safe rate for most adults. Larger deficits risk muscle loss, metabolic adaptation, and nutritional deficiencies. A milder deficit of 250 calories (0.5 lb/week loss) is more sustainable and preserves more lean mass.
For weight gain (muscle building), a surplus of 250-300 calories is typically sufficient when combined with progressive resistance training. Larger surpluses tend to produce more fat gain without additional muscle benefit. Track your strength progress with the One Rep Max Calculator to ensure your surplus is being used for muscle growth.
Regardless of your goal, adequate protein intake is critical. Research consistently shows that 1.6-2.2g of protein per kg of body weight optimizes body composition outcomes. Use the Macro Calculator to balance your remaining calories between carbohydrates and fat.
Safe Rate of Weight Change
A 500-calorie daily deficit produces ~1 lb/week fat loss — the safe maximum for most adults. Larger deficits risk muscle loss and metabolic adaptation. For muscle gain, a 250–300 calorie surplus is sufficient with progressive resistance training. Track strength with One Rep Max, body composition with Body Fat, and ensure adequate protein (1.6–2.2g/kg). Split calories into macros with the Macro Calculator.
Metabolic Adaptation
When you consistently eat below your TDEE, your body gradually reduces its metabolic rate — a survival mechanism called metabolic adaptation. This is why weight loss plateaus occur. Research shows that metabolic rate can drop 10-15% beyond what's predicted by weight loss alone. Combat this by incorporating periodic refeeds (1-2 days per week at maintenance calories), maintaining resistance training to preserve muscle, and ensuring adequate protein intake.
Frequently Asked Questions
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