How the calorie calculator works
Your daily calorie needs are made of two parts. First is your Basal Metabolic Rate (BMR) — the energy your body burns at rest to keep your heart beating, lungs breathing and brain working. Second is everything you do on top of that: walking, working, exercise and even digesting food. Together they form your Total Daily Energy Expenditure (TDEE), the number of calories that keeps your weight stable.
This calculator estimates BMR with the Mifflin-St Jeor equation, which studies have found to be the most accurate everyday formula for healthy adults, then multiplies it by an activity factor:
| Activity level | Multiplier | Example |
|---|---|---|
| Sedentary | × 1.2 | Desk job, little exercise |
| Lightly active | × 1.375 | Light exercise 1–3 days/week |
| Moderately active | × 1.55 | Exercise 3–5 days/week |
| Very active | × 1.725 | Hard exercise 6–7 days/week |
| Extra active | × 1.9 | Physical job plus training |
Calories for weight loss and weight gain
A pound of body fat stores roughly 3,500 calories, so eating about 500 calories below your TDEE each day leads to around 1 lb (0.45 kg) of weight loss per week, and 250 calories below gives about half a pound. Real-world results vary with water weight, muscle changes and how accurately food is tracked, so treat the numbers as a starting point and adjust after 2–3 weeks based on your actual progress.
For safety, the calculator never suggests going below 1,200 calories a day for women or 1,500 for men. Very low-calorie diets should only be followed under medical supervision.
What about macros?
The example macro split sets protein at 1.6 g per kg of body weight — a level research links to keeping muscle while dieting — fat at 28% of calories, and the rest as carbohydrates. Protein and carbs provide 4 calories per gram; fat provides 9.
Tips for accurate results
- Be honest about activity — most people overestimate. If unsure, choose one level lower.
- If you know your body fat percentage, choose the Katch-McArdle formula; it accounts for lean mass and suits very muscular people.
- Recalculate after every 10–15 lb (5–7 kg) of weight change.
- Pair this with the BMI calculator to see your healthy weight range, or the BMR calculator to compare formulas.
This calculator gives general estimates for healthy adults and is not medical advice. Pregnant or breastfeeding women, people with medical conditions and anyone with a history of disordered eating should seek guidance from a doctor or registered dietitian.
Frequently asked questions
How many calories should I eat to lose weight?
About 500 calories below your maintenance (TDEE) for roughly 1 lb (0.45 kg) of loss per week — but not below 1,200 (women) or 1,500 (men) per day without medical supervision.
What is TDEE?
Total Daily Energy Expenditure — the calories you burn in a day including rest, daily movement and exercise. Eating at your TDEE keeps your weight stable.
Which formula is most accurate?
Mifflin-St Jeor is the most accurate general formula for most adults. Katch-McArdle can be better if you know your body fat percentage.
Why am I not losing weight at the suggested calories?
Calculators estimate averages. Tracking errors, water retention and individual metabolism differences are common; adjust intake by 100–200 calories after 2–3 weeks.