Calorie Deficit Calculator
Losing weight comes down to eating a little less than your body uses. This calculator estimates your maintenance calories with two formulas, then shows your daily target for a 500, 750 or 1,000 kcal deficit — and roughly how long it could take to reach your goal weight.
Calories per day
| Formula | Maintenance | Target |
|---|---|---|
| Mifflin-St Jeor BMR | ||
| MET BMR |
Maintenance (TDEE) = BMR × . Target = maintenance − kcal. Mifflin-St Jeor and MET are two different formulas, shown separately.
Expected loss
kg/week
NHLBI · ≈7,700 kcal per kg
Time to goal
weeks
Add a goal weight below your current weight
kg at kcal/day
Real-world loss usually slows over time: as your weight drops, so do your maintenance calories. Recalculate every few kilos.
Your results are attached to the form below
These figures are estimates for general awareness only and are not medical advice or a diagnosis. Read our Medical Disclaimer.
Want a Plan Built Around Your Numbers?
A certified dietitian will turn these figures into a diet that fits your routine and your food.
How this is calculated
Maintenance calories (TDEE) = BMR × activity factor (PAL). BMR is shown by two methods, separately: Mifflin-St Jeor (1990), which uses your weight, height, age and sex, and the MET method (24 kcal per kg per day for men, 22.5 for women), which uses weight only. Each activity level has a PAL range rather than a single figure, so maintenance and target calories are shown as ranges. The deficit options follow the US National Institutes of Health (NHLBI) guidance of 500–1,000 kcal per day, and weekly weight loss is estimated with the classic rule of about 7,700 kcal per kg of body fat (3,500 kcal per pound).
What is a calorie deficit?
A calorie deficit means eating fewer calories than your body burns in a day. Your body makes up the difference from its stored energy, mainly body fat. The bigger the deficit, the faster the weight loss — but also the harder it is to sustain, and the greater the risk of losing muscle and missing out on nutrients.
How big should the deficit be?
The US National Institutes of Health guidance for adults is a deficit of 500 to 1,000 kcal a day, which typically gives a loss of about 0.5 to 1 kg a week. It also recommends that low-calorie diets stay around 1,000–1,200 kcal a day for most women and 1,200–1,600 kcal a day for men. If your target comes out below that, choose a smaller deficit and add activity instead, or speak to a dietitian before going further.
Why two formulas?
Mifflin-St Jeor takes your height, age and sex into account; the MET method uses only your weight. They will usually give slightly different answers, especially for people who are tall or older. Seeing both side by side shows you a realistic range rather than a falsely precise single number.
Why weight loss slows down
As you lose weight, your body needs fewer calories, so the same intake gives a smaller deficit over time. Recalculate every few kilos — and if progress stalls, that is the point where a personalised plan helps most.
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- Maintenance Calorie Calculator The calories that keep your weight steady — today, and at your goal weight, so you know what to eat once you get there.
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