Calorie Calculator — How Many Calories Should You Eat a Day?
To hold your weight steady, most adults need between 1,600 and 3,000 calories a day. The number depends on your size, sex, age and how much you move. This calculator estimates your total daily energy expenditure (TDEE) using the Mifflin-St Jeor equation — eat that amount to maintain, or subtract about 500 kcal a day to lose roughly 0.5 kg per week.
What is calorie calculator?
Your body burns energy even when you do nothing. That baseline is your basal metabolic rate (BMR), typically 60 to 75 percent of everything you burn in a day.
On top of BMR sits everything else: walking, fidgeting, working out, and the energy cost of digesting food. Together they make up your total daily energy expenditure, or TDEE.
TDEE is the single most useful number in nutrition planning, because every goal — losing fat, maintaining, building muscle — is just TDEE plus or minus a margin.
How daily calorie needs are calculated
This calculator uses the Mifflin-St Jeor equation, which is currently the most widely accepted predictor of resting metabolic rate. Your BMR is then multiplied by an activity factor ranging from 1.2 (sedentary) to 1.9 (very active) to reach your TDEE. A deficit of 500 kcal per day corresponds to about 0.45 kg of fat loss per week, since one kilogram of body fat is roughly 7,700 kcal.
Men: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5
Women: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161
TDEE = BMR × activity factor (1.2 – 1.9)Source: Mifflin et al., A new predictive equation for resting energy expenditure (1990).
How to use this calculator
- Choose metric or imperial units.
- Enter your sex, age, height and weight.
- Select the activity level that honestly matches your week — most people overestimate here.
- Read your maintenance calories, then use the cut or bulk rows below them.
- Re-check every 5 kg of weight change, because your needs drop as you get lighter.
Frequently asked questions
How many calories should I eat to lose weight?
Subtract 500 kcal from your TDEE for about 0.5 kg per week, or 1,000 kcal for about 1 kg per week. Do not go below 1,200 kcal for women or 1,500 kcal for men without medical supervision.
Why do two calculators give me different numbers?
They use different equations. Mifflin-St Jeor, Katch-McArdle and Harris-Benedict all produce slightly different results, and all carry roughly 10 percent error. Pick one and track your real-world weight trend instead of chasing precision.
Do I need to eat back calories burned during exercise?
Usually not. Fitness trackers and cardio machines overestimate burn considerably. If your activity level is already set honestly in this calculator, your exercise is counted.
How accurate is this without knowing my body fat?
Mifflin-St Jeor is accurate to roughly plus or minus 10 percent for most people. If you know your body fat percentage, the Katch-McArdle equation is more accurate for lean, muscular individuals.
Will my calorie needs change as I lose weight?
Yes, and this is why weight loss stalls. A lighter body burns less at rest, and metabolism also adapts slightly downward during a long deficit. Recalculate every 5 kg lost.
Related calculators
- BMR Calculator — Calculate your basal metabolic rate with the Mifflin-St Jeor equation, or use Katch-McArdle if you know your body fat percentage.
- Macro Calculator — Free macro calculator. Get your daily protein, carbohydrate and fat targets in grams based on your TDEE and whether you want to lose fat, maintain or build muscle.
- Protein Intake Calculator — Calculate your daily protein target in grams based on body weight and activity level, with per-meal breakdowns for 3 or 4 meals.
These figures are estimates from population formulas, not medical advice. Individual needs vary. If you are pregnant, managing a medical condition, or under 18, talk to a doctor before changing your diet.