This calorie calculator estimates your basal metabolic rate (BMR), the energy your body uses at complete rest, and your total daily energy expenditure (TDEE), which adds the calories burned through daily activity and exercise. TDEE is the number of calories that keeps your weight stable.
From that it builds a simple table of daily targets to lose or gain weight at different rates, with the approximate change per week. It uses the Mifflin-St Jeor equation, which studies have found to be the most accurate of the common formulas for most adults.
How to use the Calorie Calculator tool
- Choose metric or imperial units and select male or female.
- Enter your age, weight and height.
- Pick the activity level that matches a typical week.
- Read your maintenance calories (TDEE) and BMR.
- Use the goal table to choose a daily calorie target for losing or gaining weight.
Why use ToolOrca Calorie Calculator
- Mifflin-St Jeor BMR equation
- Five activity levels from sedentary to extra active
- Targets for mild, normal and fast weight loss or gain
- Approximate weekly weight change in kg or lb
- Warnings for very low calorie targets
- Formula shown with your numbers
How your calorie needs are calculated
Mifflin-St Jeor: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) + 5 for men, or − 161 for women. TDEE = BMR × activity factor: 1.2 sedentary, 1.375 lightly active, 1.55 moderately active, 1.725 very active and 1.9 extra active.
Worked example: a 30-year-old man who weighs 80 kg and is 180 cm tall has a BMR of 10 × 80 + 6.25 × 180 − 5 × 30 + 5 = 1,780 kcal. Exercising 3–5 days a week (× 1.55), his TDEE is about 2,759 kcal a day. Eating about 2,259 kcal a day (a 500 kcal deficit) would lose roughly 0.45 kg (1 lb) a week.
Using the results safely
One kilogram of body fat stores roughly 7,700 kcal (about 3,500 kcal per pound), so a daily deficit of 500 kcal gives about 0.45 kg a week. Real results vary because metabolism adapts and water weight changes. A loss of 0.5–1 kg a week is generally considered sustainable. These numbers are estimates for information only and are not medical or dietary advice; people who are pregnant, under 18 or managing a health condition should ask a doctor or dietitian.
Frequently asked questions
How many calories should I eat to lose weight?
Eat about 500 kcal less than your TDEE to lose roughly 0.45 kg (1 lb) a week. For a moderately active 30-year-old woman who weighs 65 kg and is 165 cm tall, TDEE is about 2,124 kcal, so around 1,624 kcal a day.
What is the difference between BMR and TDEE?
BMR is the energy you burn at complete rest just to stay alive. TDEE is BMR multiplied by an activity factor and is the total you burn in a normal day. For a 65 kg, 165 cm, 30-year-old woman, BMR is about 1,370 kcal and TDEE at a light activity level is about 1,884 kcal.
Which activity level should I choose?
Choose sedentary if you sit most of the day and rarely exercise, lightly active for exercise 1–3 days a week, moderately active for 3–5 days, very active for hard exercise 6–7 days, and extra active for a physical job plus training. Most people overestimate, so pick the lower level if unsure.
How accurate is the Mifflin-St Jeor equation?
It predicts resting energy within about 10% for most healthy adults. Treat the result as a starting point, track your weight for 2–3 weeks and adjust by 100–200 kcal if needed.