Calorie Calculator
Estimate your daily calorie needs with the Mifflin-St Jeor equation, pick an activity level and a goal — lose, maintain, or gain — and get a simple protein, fat, and carb split.
⚠️ Educational estimate — not medical adviceYour numbers
Metric units (kg, cm). Everything runs in your browser — nothing is sent anywhere.
15–80
30–300 kg
120–230 cm
Your daily targets
Macro split
Protein 1.6–2.2 g/kg body weight (this goal: — g/kg) · fat 25% of calories · carbs fill the rest.
How it works
1. BMR — the Mifflin-St Jeor equation estimates the calories you burn at rest: men 10×weight + 6.25×height − 5×age + 5; women the same with −161 instead of +5.
2. TDEE — BMR multiplied by your activity factor (1.2–1.9).
3. Goal — maintain eats at TDEE; lose subtracts 500 kcal/day (≈ −0.45 kg/week, since 1 kg of body fat ≈ 7,700 kcal); gain adds 500 kcal/day.
4. Macros — protein 1.6–2.2 g/kg (higher in a deficit to protect muscle), fat 25% of calories, carbohydrates fill the remainder.
Worked example: a 30-year-old woman, 65 kg, 165 cm, moderately active, goal lose → BMR 1,370 kcal → TDEE 2,124 kcal → target 1,624 kcal/day → protein 143 g, fat 45 g, carbs 161 g.
Frequently asked questions
How many calories should I eat per day?
It depends on your body and activity level. This calculator estimates your BMR with the Mifflin-St Jeor equation, multiplies it by an activity factor to get your TDEE, then adjusts for your goal: the same TDEE to maintain weight, about 500 kcal less per day to lose roughly 0.45 kg per week, or about 500 kcal more per day to gain weight.
What is BMR and how does the Mifflin-St Jeor equation work?
BMR (basal metabolic rate) is the energy your body burns at complete rest to keep you alive. The Mifflin-St Jeor equation estimates it from weight, height, age, and sex: for men, 10 x weight(kg) + 6.25 x height(cm) - 5 x age + 5; for women the same formula ends with - 161 instead of + 5. It is the most widely validated BMR formula for general use.
What is TDEE?
TDEE (total daily energy expenditure) is your BMR plus the calories you burn through daily activity and exercise. This calculator multiplies BMR by one of five activity factors: 1.2 sedentary, 1.375 lightly active, 1.55 moderately active, 1.725 very active, or 1.9 extremely active.
How many calories do I need to lose weight?
A daily deficit of about 500 kcal below your TDEE typically leads to roughly 0.45 kg of fat loss per week, since one kilogram of body fat stores about 7,700 kcal. This calculator shows a warning if the resulting target falls below 1,200 kcal per day for women or 1,500 for men, which most guidelines consider too low without professional supervision.
How many calories do I need to gain weight?
A daily surplus of about 500 kcal above your TDEE typically leads to roughly 0.45 kg of weight gain per week. Pair the surplus with resistance training and enough protein (around 1.6 g per kg of body weight) so more of the gain is muscle rather than fat.
How much protein do I need per day?
Research generally supports 1.6 to 2.2 grams of protein per kilogram of body weight per day for active people. This calculator targets the top of that range (2.2 g/kg) when losing weight to protect muscle, the middle (1.8 g/kg) for maintenance, and the lower end (1.6 g/kg) when gaining.
Why does this calculator set fat to 25% of calories?
About 20 to 35 percent of calories from fat is the commonly recommended range for hormone health and nutrient absorption. This calculator uses the midpoint, 25 percent, then assigns all remaining calories to carbohydrates, which are the most flexible macro to adjust.
Is this calorie calculator medical advice?
No. It is an educational estimate based on population formulas. It does not diagnose, treat, or replace professional guidance. Talk to a doctor or registered dietitian before starting a diet, especially if you are pregnant, breastfeeding, managing a medical condition, or have a history of disordered eating.
How is this different from your TDEE calculator?
This tool gives you one practical answer: a daily calorie target plus a macro split for your goal. Our TDEE calculator compares four energy-expenditure formulas side by side (Mifflin-St Jeor, Harris-Benedict, Katch-McArdle, and Cunningham) for people who want the methodological detail.
How is this different from your BMI weight loss planner?
This tool estimates general daily calorie needs for any goal. Our BMI weight loss planner starts from your BMI and builds a week-by-week deficit timeline toward a specific target weight. Use this calculator for the daily number, the planner for the schedule.
What should I do if my target is below 1,200 calories?
Treat it as a signal to change the plan, not to eat that little. Options include choosing a lighter activity assumption, a smaller deficit, or simply maintaining while you build activity up. Very low calorie intakes can cause nutrient deficiencies and muscle loss, so discuss them with a professional first.
Does this calculator support pounds and inches?
Currently it uses metric units only (kilograms and centimeters), which is what the Mifflin-St Jeor equation takes directly. To convert: divide pounds by 2.205 to get kilograms, and multiply inches by 2.54 to get centimeters.
Free tool by NRTechStudio