How many calories do you need?
Your daily calorie needs depend on your size, age, sex and how active you are. This calculator first estimates your basal metabolic rate (BMR) — the energy your body uses at rest — with the Mifflin-St Jeor equation, which the Academy of Nutrition and Dietetics considers the most accurate for most adults:
- Men:
BMR = 10 × kg + 6.25 × cm − 5 × age + 5 - Women:
BMR = 10 × kg + 6.25 × cm − 5 × age − 161
It then multiplies BMR by an activity factor (1.2 to 1.9) to estimate your total daily energy expenditure (TDEE) — the calories you burn on an average day, and roughly what you need to maintain your weight.
Calories for weight loss or gain
A pound of body fat stores roughly 3,500 calories, so a daily deficit of about 500 calories is often cited for losing about 1 pound (0.45 kg) a week. In reality, weight change slows as your body adapts, which is why the NIH Body Weight Planner uses a dynamic model. Health agencies generally recommend gradual loss of 1–2 pounds per week and advise against very-low-calorie diets without medical supervision. This calculator never suggests targets below about 1,200 calories (women) or 1,500 calories (men).
Typical calorie needs
According to the Dietary Guidelines for Americans, adult women generally need about 1,600–2,400 calories a day and adult men about 2,000–3,000, depending on age and activity. Health Canada's estimated energy requirements are similar.
Where calories come from
Federal guidelines suggest getting 45%–65% of calories from carbohydrates, 10%–35% from protein and 20%–35% from fat. Quality matters as much as quantity: vegetables, fruits, whole grains, lean proteins and healthy fats keep you full and nourished. Check your weight category with our BMI calculator.
These are estimates for healthy adults. Pregnant or breastfeeding people, athletes in training and anyone with a medical condition should get personalized advice from a doctor or registered dietitian.
Frequently asked questions
How many calories should I eat to lose weight?
What is the difference between BMR and TDEE?
How accurate are calorie calculators?
Do I need to count calories?
Sources & methodology
This calculator was last reviewed on November 1, 2026. Figures are based on the following official and primary sources:
- Dietary Guidelines for Americans 2020–2025 (estimated calorie needs)
- NIH – Body Weight Planner
- Health Canada – Estimated energy requirements
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