Calorie Calculator

Features

• Estimates BMR with the Mifflin-St Jeor equation
• Applies your activity level for maintenance calories
• Targets for losing, maintaining or gaining weight
• A suggested protein, carb and fat split in grams
• Metric or imperial, runs entirely in your browser

How to use it

1. Choose your units and enter your age, sex, height and weight.
2. Pick the activity level that matches a typical week.
3. Read your BMR and maintenance calories.
4. Choose a goal to see your daily target and macro split.

How calorie needs are estimated, and the caveats

Your body burns energy even at complete rest to keep your heart, brain and other organs running. That baseline is your basal metabolic rate, or BMR. This calculator estimates it with the Mifflin-St Jeor equation, which is one of the most accurate general formulas and uses your weight, height, age and sex. Your total daily energy expenditure, or TDEE, is then your BMR multiplied by an activity factor, because moving around, exercising and even digesting food all burn additional energy on top of the resting baseline.

To change weight, you adjust intake relative to that maintenance number. Eating fewer calories than you burn creates a deficit and you tend to lose weight; eating more creates a surplus and you tend to gain. A commonly used guide is that a deficit or surplus of about 500 calories a day corresponds to roughly half a kilogram, or about a pound, a week, though the real figure varies from person to person. The macro split shown here is one balanced suggestion, splitting your target calories across protein, carbohydrate and fat, with protein and carbs at four calories a gram and fat at nine.

Treat every number here as an estimate, not a prescription. Formulas like Mifflin-St Jeor describe an average person and cannot account for your individual metabolism, body composition, medical conditions or medications, and activity multipliers are broad brush by nature. Use the results as a sensible starting point, watch how your body actually responds over a few weeks, and adjust from there. If you have a health condition, are pregnant, or are planning a significant change to how you eat or train, talk to a doctor or a registered dietitian rather than relying on a calculator.