How this calorie calculator works
Your daily calorie needs have two parts. Basal metabolic rate (BMR) is the energy your body burns at complete rest just to keep you alive: breathing, circulation and keeping warm. Total daily energy expenditure (TDEE) adds everything else you do, from walking and working to exercise. TDEE is your maintenance calories: eat about this much and your weight should stay roughly stable.
This calculator estimates BMR with the Mifflin-St Jeor equation, which research has found to be among the most accurate formulas for most adults:
- Men: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5
- Women: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161
It then multiplies BMR by an activity factor to get TDEE. US units are converted to metric first, so both give the same answer.
Activity multipliers
- Sedentary (×1.2): desk job, little or no exercise.
- Lightly active (×1.375): light exercise 1–3 days a week.
- Moderately active (×1.55): moderate exercise 3–5 days a week.
- Very active (×1.725): hard exercise 6–7 days a week.
- Extra active (×1.9): physical job plus training, or training twice a day.
Most people overestimate their activity. If you're unsure, pick the lower level and adjust after a few weeks.
Calories to lose or gain weight
A common rule of thumb is that a pound of body fat stores about 3,500 calories (about 7,700 per kilogram). Eating 500 calories a day below maintenance therefore leads to roughly 1 lb (about 0.5 kg) of loss per week. The calculator shows targets for mild (0.5 lb / 0.25 kg per week), standard (1 lb / 0.5 kg) and extreme (2 lb / 1 kg) loss, plus gain. Real results slow over time because your TDEE drops as you lose weight, so recalculate every 10 lb or so.
Minimum calorie intake
Very low intakes make it hard to get enough protein, vitamins and minerals and can cause muscle loss and fatigue. Common guidance is not to go below about 1,200 calories a day for women or 1,500 for men without medical supervision, so this calculator raises any target below those levels and flags it.
Limitations
Every formula predicts an average; your real metabolism can differ by 10% or more. Mifflin-St Jeor does not account for body composition, so very muscular people may burn more than estimated. It is not designed for children, teens, or pregnant or breastfeeding women. Track your weight for 2–3 weeks and adjust calories based on real results.
This calculator is for informational purposes only and is not medical advice. Consult a doctor or registered dietitian before starting a diet, especially if you have a health condition.
Frequently asked questions
What is TDEE?
Total daily energy expenditure is the number of calories you burn in a day, including your basal metabolism, digestion and all activity. It equals your maintenance calories.
What is the difference between BMR and TDEE?
BMR is the energy you burn at complete rest. TDEE is BMR multiplied by an activity factor (1.2 to 1.9) to include daily movement and exercise.
How many calories should I eat to lose weight?
A deficit of about 500 calories a day below your TDEE leads to roughly 1 lb (0.5 kg) of weight loss per week for most people.
Is the Mifflin-St Jeor equation accurate?
It is considered one of the most accurate BMR formulas for healthy adults, but individual results can vary by 10% or more.
What is the minimum number of calories I should eat?
Common guidance is at least about 1,200 calories a day for women and 1,500 for men unless supervised by a healthcare professional.
Why am I not losing weight at my calorie target?
Calorie counts are often underestimated, activity is often overestimated, and TDEE falls as you lose weight. Track intake carefully and adjust by 100–200 calories after a few weeks.