Calorie Calculator
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Calorie Goals
These calculations use the Mifflin-St Jeor equation and are estimates. Individual needs may vary. Consult a healthcare professional for personalized advice.
Understanding Your Calorie Needs
Your daily calorie needs depend on several factors including age, sex, height, weight, and physical activity level. This calculator uses two key measurements:
Basal Metabolic Rate (BMR)
BMR represents the number of calories your body needs to perform basic life-sustaining functions like breathing, circulation, and cell production. According to the NIH, BMR accounts for about 60-75% of your daily calorie expenditure.
Total Daily Energy Expenditure (TDEE)
TDEE is your BMR multiplied by an activity factor to account for physical activity and exercise. This represents your total calorie needs to maintain your current weight. The USDA Dietary Guidelines use similar calculations to establish recommended calorie intakes.
This calculator uses the Mifflin-St Jeor equation, which research has shown to be one of the most accurate predictive equations for calculating BMR. The equation was validated in a study published in the American Journal of Clinical Nutrition.
Sources: NIH National Institute of Diabetes and Digestive and Kidney Diseases; USDA Dietary Guidelines for Americans 2020-2025
Frequently Asked Questions
How accurate is this calorie calculator?
The Mifflin-St Jeor equation is considered one of the most accurate formulas, with a margin of error of about ±10%. However, individual metabolic rates can vary based on factors like genetics, muscle mass, hormones, and medical conditions. Use these numbers as a starting point and adjust based on your actual results.
How much should I eat to lose weight safely?
The CDC recommends gradual weight loss of 1-2 pounds per week. This typically requires a deficit of 500-1000 calories per day. However, women should not eat less than 1200 calories per day, and men should not eat less than 1500 calories per day without medical supervision.
Why does my gender affect calorie needs?
On average, men have more muscle mass and less body fat than women of the same age and weight. Since muscle tissue burns more calories than fat tissue, men typically have higher calorie needs. The Mifflin-St Jeor equation accounts for this difference.
How do I choose the right activity level?
Be honest about your typical activity. Most people overestimate their activity level. Sedentary means little to no exercise beyond daily living activities. If you exercise intensely most days of the week, you might be moderately or very active. When in doubt, start with a lower activity level and adjust based on results.
Should I eat back exercise calories?
Your TDEE already includes your typical exercise based on your selected activity level. You generally should not eat back additional calories unless you do significantly more exercise than usual. The NIH notes that people often overestimate calories burned during exercise.
Do calorie needs change with age?
Yes, BMR typically decreases with age due to loss of muscle mass and changes in hormonal and metabolic function. This is why the calculator asks for your age. The USDA Dietary Guidelines show that calorie needs generally decrease by about 100-200 calories per decade after age 30.