BMR (Basal Metabolic Rate): The calories your body burns at complete rest just to maintain basic functions like breathing and circulation. This is the minimum energy your body needs even if you stayed in bed all day.
Maintenance Calories: Your total daily energy expenditure including physical activity. Eating at this level should keep your weight roughly stable over time.
Mild Weight Loss (−250 cal): A small daily deficit that typically produces about half a pound of weight loss per week. This is the most sustainable approach for long-term results.
Weight Loss (−500 cal): A moderate deficit targeting about one pound per week, the rate most commonly recommended by health professionals.
Extreme Weight Loss (−1,000 cal): An aggressive deficit targeting about two pounds per week. This rate may not be sustainable and is generally only appropriate under medical supervision.
How This Calculator Works
You enter your age, gender, height, weight, and activity level. The tool calculates your Basal Metabolic Rate using the Mifflin-St Jeor equation — considered the most accurate for healthy adults — then multiplies by an activity factor to get maintenance calories. The three deficit tiers subtract 250, 500, or 1,000 calories from maintenance based on the approximation that 3,500 calories equals about one pound of body fat.
Quick Questions
How accurate is the Mifflin-St Jeor equation?
Studies show it predicts BMR within about 10% for most healthy adults. Individual variation from genetics, muscle mass, and hormonal factors means your actual BMR may differ slightly from the estimate.
Which activity level should I choose?
Choose based on your overall weekly routine, not your hardest workout day. Most people with desk jobs who exercise 3–4 times per week fall into the "Moderately Active" category.
Should I eat below my BMR?
Eating below your BMR for extended periods is generally not recommended. It can lead to nutrient deficiencies, muscle loss, and metabolic slowdown. Consult a healthcare provider before attempting very low calorie intake.
Does this calculator work for athletes?
It provides a reasonable starting estimate, but athletes with high muscle mass may have a higher BMR than the equation predicts. Athletes should also consider sport-specific nutritional needs beyond simple calorie counting.
Why do men and women get different results?
The Mifflin-St Jeor equation uses different constants for each gender because men typically have more lean muscle mass, which burns more calories at rest. The difference is +5 for males and −161 for females.
Estimate only. Results reflect your inputs and standard formulas — they are not financial, tax, legal, health, or investment advice. Verify important decisions with a qualified professional.