Calorie Calculator
Estimate the calories your body burns in a day and how many to eat to hold, drop or add weight. Built on the Mifflin-St Jeor equation that dietitians rely on.
Fill in your details and press Calculate to see your daily calorie needs.
How the calculator works
Enter your stats
Give your sex, age, height and weight. These feed the Mifflin-St Jeor formula, the most accurate simple equation for resting metabolism.
Pick an activity level
Choose the option that matches a typical week. Be honest here, since activity is the single biggest lever on your daily total.
See your targets
You get your maintenance calories plus ready-made targets for slow or faster weight loss and gain, so you can choose a pace.
BMR, TDEE and your goal
BMR is your baseline
Basal metabolic rate is the energy you burn at complete rest just to keep your body running. It is the floor your daily needs are built on.
TDEE adds movement
Total daily energy expenditure multiplies your BMR by an activity factor. That number is roughly what you need to eat to keep your weight steady.
A deficit or surplus
Eat below TDEE and you lose weight; eat above it and you gain. Around 7,700 kcal equals a kilogram, which is why a 500 kcal daily gap shifts about half a kilo a week.
Understanding your calorie numbers
Your body spends energy in three main ways: keeping you alive at rest, moving around, and digesting food. This calculator estimates the first with the Mifflin-St Jeor equation, then scales it up for the second and third with an activity multiplier. The result is your total daily energy expenditure, or TDEE.
The Mifflin-St Jeor equation
Published in 1990, it is now the equation most registered dietitians reach for because it tracks real-world measurements more closely than older formulas. For men it is 10 × weight in kg plus 6.25 × height in cm minus 5 × age plus 5. For women the final constant is minus 161 instead.
Choosing a sensible deficit
A moderate cut of 500 kcal a day tends to be sustainable and points to roughly half a kilogram of loss per week. Aggressive cuts work faster but are harder to stick to and can cost you muscle. Many people find a smaller 250 kcal trim easier to live with over months.
| Goal | Daily change | Rough weekly result |
|---|---|---|
| Slow loss | −250 kcal | ~0.25 kg |
| Standard loss | −500 kcal | ~0.5 kg |
| Slow gain | +250 kcal | ~0.25 kg |
| Standard gain | +500 kcal | ~0.5 kg |
Why estimates vary from person to person
Two people with identical stats can burn different amounts because of genetics, muscle mass, hormones and non-exercise movement like fidgeting. Treat the number as a starting point: track your weight for two or three weeks and nudge your intake up or down based on what actually happens on the scale.
Frequently asked questions
Which formula does this use?
It uses the Mifflin-St Jeor equation for basal metabolic rate, then applies a standard activity multiplier to give total daily energy expenditure. It is widely regarded as the most reliable simple method.
How many calories to lose weight?
Eat below your maintenance number. A deficit of about 500 kcal a day usually produces around half a kilogram of loss per week while staying manageable.
What activity level should I pick?
Choose the one matching a normal week, not your best week. Most people with a desk job who train a few times a week fall under light or moderate rather than active.
Are my details stored anywhere?
No. The maths runs in your browser and nothing you type is uploaded or saved. Refresh the page and it is gone.
Should I eat back exercise calories?
The activity multiplier already includes your typical exercise, so you generally should not add it twice. Only adjust if your week is unusually active or quiet.
Is a very low calorie target safe?
Dropping too low can cost muscle and leave you short on nutrients. As a general guide, avoid going under about 1,500 kcal for men or 1,200 for women without professional supervision.