How to use the calorie calculator
- Age and sex, enter your age in years and pick your sex, both change your metabolic rate.
- Height and weight, enter your measurements. Switch between metric (cm, kg) and imperial (ft, in, lb) with the unit toggle.
- Activity level, choose how active you are on a typical day, from sedentary to extra active.
- Goal, pick whether you want to maintain, lose or gain weight to apply a calorie adjustment.
- Read your maintenance calories, goal calories and BMR, they update instantly as you type.
Nothing is submitted or stored: the numbers never leave your device, so you can check your figures privately.
How your daily calories are calculated
The calculator starts with your Basal Metabolic Rate (BMR), the energy your body burns at complete rest just to keep you alive. It uses the widely trusted Mifflin-St Jeor equation, which is based on your weight, height, age and sex. For men the formula is 10 x weight(kg) + 6.25 x height(cm) - 5 x age + 5, and for women it is 10 x weight(kg) + 6.25 x height(cm) - 5 x age - 161.
Your BMR is then multiplied by an activity factor to give your Total Daily Energy Expenditure (TDEE), which is roughly how many calories you burn across a normal day. The factors are: Sedentary 1.2 (little or no exercise), Lightly active 1.375 (light exercise 1 to 3 days a week), Moderately active 1.55 (moderate exercise 3 to 5 days), Very active 1.725 (hard exercise 6 to 7 days), and Extra active 1.9 (very hard exercise or a physical job).
Finally, your goal adjusts that number. Eating at your TDEE keeps your weight stable. To lose weight the tool subtracts 500 calories a day, a deficit that typically loses about half a kilogram (one pound) a week. To gain weight it adds 500 calories a day. The optional macro split divides your goal calories into protein, carbs and fat using a balanced 30 / 40 / 30 ratio as a simple starting point.
An estimate, not a diagnosis
Medical disclaimer: This calculator is for general information only and is not medical advice. Calorie needs vary with genetics, hormones, muscle mass and health conditions, so treat the result as a starting point and adjust based on your real progress. Always consult a qualified doctor or dietitian before making big changes to your diet.
Frequently asked questions
How many calories should I eat a day?
It depends on your age, sex, height, weight and activity. This calculator estimates your maintenance calories with the Mifflin-St Jeor formula, then adjusts for your goal. Many adults need between 1,800 and 2,800 calories a day, but your figure can sit outside that range.
How is BMR calculated?
It uses the Mifflin-St Jeor equation. Men: 10 x weight(kg) + 6.25 x height(cm) - 5 x age + 5. Women: 10 x weight(kg) + 6.25 x height(cm) - 5 x age - 161. BMR is the energy your body uses at complete rest.
What is TDEE?
Total Daily Energy Expenditure, your BMR multiplied by an activity factor (1.2 sedentary up to 1.9 extra active). It estimates the calories you burn in a typical day, so eating that amount should keep your weight stable.
How many calories to lose weight?
A common start is about 500 calories a day below maintenance, which loses roughly half a kilogram (one pound) a week. Choose the Lose weight goal to apply this deficit automatically.
Is this calorie calculator accurate?
It gives a solid estimate, but every body is different. Real needs vary with genetics, hormones and muscle mass, so adjust based on your real results and speak to a professional for personal advice.