How the calorie calculator works
The calculator first estimates your basal metabolic rate (BMR), the energy your body uses at complete rest, using the Mifflin-St Jeor equation. It then multiplies BMR by an activity factor to estimate your total daily energy expenditure (TDEE), which is the number of calories that keeps your weight stable.
Men: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5
Women: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161
Maintenance calories = BMR × activity factor
Activity factors
| Activity level | Factor |
|---|---|
| Little or no exercise | 1.2 |
| Light exercise, 1 to 3 days a week | 1.375 |
| Moderate exercise, 3 to 5 days a week | 1.55 |
| Hard exercise, 6 to 7 days a week | 1.725 |
| Physical job or training twice a day | 1.9 |
Most people overestimate how active they are. If you are unsure, choose the lower level.
Worked example
A 30-year-old woman who is 170 cm tall and weighs 68 kg has a BMR of about 1,432 calories. With light exercise, her maintenance intake is roughly 1,968 calories a day.
Understanding the results
Gradual weight loss and gain show your maintenance figure 250 calories lower or higher. Small, steady changes are easier to keep up and are the approach most health services recommend. BMI is a quick screening measure of weight for height. It doesn't account for muscle, age or body shape, so treat it as a rough guide. The macro split shows a balanced mix of 25% protein, 50% carbohydrates and 25% fat at maintenance.
Limits of any calorie calculator
Equations like Mifflin-St Jeor are averages. Your real needs can differ by 10% or more because of genetics, muscle mass, sleep, medication and health conditions. The results are not suitable for children, teenagers, or during pregnancy or breastfeeding. If you have a medical condition or a history of disordered eating, please talk to a doctor or registered dietitian rather than relying on a calculator.
Frequently asked questions
What is the difference between BMR and TDEE?
BMR is the energy you use at rest. TDEE adds the energy used for daily movement and exercise.
How accurate is the Mifflin-St Jeor equation?
It is one of the most reliable general equations for adults, but individual results can still vary by around 10%.
Why is there no option for children?
Children and teenagers have different energy needs for growth, so adult equations don't apply to them.
How many grams are in a calorie of protein, carbs and fat?
Protein and carbohydrates provide about 4 calories per gram, and fat provides about 9 calories per gram.
Should I recalculate if my weight changes?
Yes. Your energy needs change with your weight and activity, so update the numbers every few months.
Last reviewed on by the Dailycaltor team.