Calorie Calculator
Find out roughly how many calories your body uses in a day, and what that means if you want to lose, maintain or gain weight. Enter your age, sex, height, weight and activity level and you get your BMR, your maintenance calories and sensible targets for each goal.
Calculated with the Mifflin-St Jeor equation, the formula most dietitians consider the best general-purpose estimate for adults.
How to use the calorie calculator
Enter your sex, age, height and weight.
Choose the activity level that honestly matches your week.
Read your maintenance calories and the targets for each goal.
Why use the Convert Now calorie calculator
BMR and TDEE
Both figures, so you can see where the energy goes.
Goal targets
Calorie numbers for mild or standard loss and gain.
Protein guide
A gram range to help preserve muscle in a deficit.
Private
Your body measurements never leave your device.
BMR and TDEE explained
Your basal metabolic rate is what your body burns doing nothing at all – running your heart, brain, lungs and cells while at complete rest. For most adults it accounts for 60–70% of daily energy use. Total daily energy expenditure multiplies that by an activity factor to include moving, working, exercising and digesting food. TDEE is the number that matters for weight: eat around it and weight is stable, eat consistently below it and you lose, above it and you gain.
Why the targets are modest
A deficit of roughly 500 calories a day produces about half a kilogram of loss per week, which research consistently finds is sustainable and preserves muscle. Much larger deficits usually backfire: they are hard to maintain, they cost lean tissue as well as fat, and they leave you tired enough to move less, which quietly shrinks the deficit you thought you had. The protein guide shown alongside the targets exists for the same reason – adequate protein during a deficit protects muscle.
Treat the number as a starting point
Every equation of this kind is a population average, accurate to within roughly 10% for most people but capable of being further off for anyone with unusual body composition, a thyroid condition, or a very high or low activity level. The practical approach is to eat at the estimate for two or three weeks, track your weight trend rather than daily fluctuations, and adjust from what actually happens.
Read the guide: What Is a Good BMI? Healthy Ranges Explained
Frequently asked questions
How many calories should I eat a day?
Your maintenance figure is shown as the main result. To lose weight, aim roughly 500 calories below it; to gain, aim 300–500 above.
What is TDEE?
Total daily energy expenditure – all the calories you burn in a day, including rest, movement, exercise and digestion.
What is BMR?
Basal metabolic rate: the calories your body uses at complete rest just to stay alive. It is the largest part of your daily total.
Which formula does this use?
Mifflin-St Jeor, which studies generally find more accurate than the older Harris-Benedict equation for modern populations.
How accurate is a calorie calculator?
Within about 10% for most adults. Use it as a starting point and adjust based on how your weight actually responds over two to three weeks.
Is this medical advice?
No. It is general information. Speak to a doctor or registered dietitian before making significant dietary changes, especially if you have a health condition.
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