How to use the Calorie Calculator
- Choose metric or imperial units, then select your sex and enter your age.
- Enter your height and current weight.
- Pick the activity level that matches a typical week, not your best week.
- Read your maintenance calories, then use the table to pick a daily target for losing, keeping or gaining weight.
Features
- Mifflin-St Jeor equation for basal metabolic rate
- Five activity levels from sedentary to extra active
- Daily targets for mild, normal and fast loss or gain
- Weekly weight change shown in kilograms and pounds
- Flags targets below commonly advised minimum intakes
- Metric and imperial units, plus kilojoules
How the calorie calculator works
Your daily energy use has two main parts. The first is your basal metabolic rate (BMR): the calories your body burns at complete rest to keep your heart beating, your lungs breathing and your cells working. The second is everything you do on top of that, from walking to the shops to training for a race. Together they make your total daily energy expenditure (TDEE), the intake that keeps your weight steady.
Step 1: BMR with the Mifflin-St Jeor equation
This calculator uses the Mifflin-St Jeor equation, published in 1990 and widely used by dietitians because it tends to be more accurate for today's adults than the older Harris-Benedict formula:
- Men: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) + 5
- Women: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) − 161
If you enter feet, inches and pounds, they are converted to centimeters and kilograms first.
Step 2: multiply by your activity level
| Activity level | Typical week | Multiplier |
|---|---|---|
| Sedentary | Desk job, little or no exercise | 1.2 |
| Lightly active | Light exercise or sport 1–3 days | 1.375 |
| Moderately active | Moderate exercise 3–5 days | 1.55 |
| Very active | Hard exercise 6–7 days | 1.725 |
| Extra active | Very hard training or a physical job | 1.9 |
Worked example
A 30-year-old man who is 180 cm tall, weighs 80 kg and exercises three to five times a week has a BMR of 10 × 80 + 6.25 × 180 − 5 × 30 + 5 = 800 + 1,125 − 150 + 5 = 1,780 kcal. Multiplying by 1.55 gives a TDEE of about 2,759 kcal a day.
Calories for losing or gaining weight
A common rule of thumb says a pound of body fat holds roughly 3,500 kcal, or about 7,700 kcal per kilogram. A daily deficit of 500 kcal therefore adds up to roughly a pound (0.45 kg) a week. The table under the result applies this rule:
- Mild: 250 kcal a day below or above maintenance, about 0.5 lb (0.23 kg) a week.
- Normal: 500 kcal a day, about 1 lb (0.45 kg) a week.
- Fast: 1,000 kcal a day, about 2 lb (0.9 kg) a week.
Real progress drifts from the rule over time. As you lose weight your BMR falls and your body adapts by using a little less energy, so the pace slows. Recalculate every few kilograms with your new weight. When gaining, a smaller surplus combined with strength training favors muscle over fat.
Getting a realistic estimate
- Be honest about activity. Most people overestimate it. If you sit most of the day and train three times a week, lightly or moderately active usually fits better than very active.
- Treat the number as a starting point. Equations describe averages, and your real needs can differ by 10% or more. Track your weight for two to three weeks and adjust by 100–200 kcal if it moves differently than expected.
- Do not go too low. Intakes under about 1,200 kcal for women or 1,500 kcal for men make it hard to get enough nutrients and are usually only used under medical supervision. The table flags targets below those levels.
- Special cases. The equation is not designed for pregnancy, breastfeeding, children or teenagers, or very muscular athletes, whose needs differ.
Pair this with the BMI Calculator to set a sensible goal weight and the Body Fat Calculator to follow changes in body composition. Results from this calculator are estimates for general information and are not medical advice.
Frequently asked questions
What is the difference between BMR and TDEE?
BMR is the energy your body uses at complete rest. TDEE adds the energy you spend moving and exercising, so it is the number of calories that keeps your weight stable.
How many calories should I eat to lose weight?
A common starting point is your TDEE minus 500 kcal a day, which works out to roughly 1 lb (0.45 kg) a week. Smaller deficits are easier to sustain, and very low intakes should be supervised by a professional.
Which activity level should I choose?
Pick the one that matches an average week, including your job. People who sit at work and exercise a few times a week are usually lightly or moderately active.
Why am I not losing weight on the calculated calories?
Equations are averages, food tracking is often a little off, and the body adapts as you lose weight. If your weight has not changed in two to three weeks, reduce your intake by 100–200 kcal or increase activity, and recalculate with your current weight.
Is this calculator suitable for everyone?
It is designed for healthy adults. It does not account for pregnancy, breastfeeding, growth in children and teens, or medical conditions that change metabolism.