Calorie Deficit Calculator
Turn a weekly weight-loss goal into a daily calorie target and a realistic timeline — an estimate of how long it will take you to reach your goal weight.
Try to keep your intake above your BMR. A 550 kcal daily deficit — roughly 0.5 kg per week — is a sustainable pace most people can hold long-term.
What is a calorie deficit calculator?
A calorie deficit calculator works out how much to eat to lose weight at a chosen pace. It starts by estimating your total daily energy expenditure (TDEE) — the calories you burn in a day — using the Mifflin-St Jeor equation with your age, gender, height and weight, then applying an activity multiplier. From there, it converts a weekly weight-loss goal (0.25 to 1 kg) into a daily calorie deficit, and a daily calorie target by subtracting that deficit from your TDEE.
Because roughly 7,700 calories are stored per kilogram of body fat, a 550 calorie daily deficit produces about half a kilogram of loss per week. The calculator also shows how many weeks (and months) it will take you to move from your current weight to your goal weight at that pace, combining four things — your maintenance calories, your planned deficit, your available energy reserve and the weight you still need to lose. Everything runs on JavaScript in your browser, so results are instant and nothing is uploaded.
How to use
- Enter your age and select your gender.
- Enter your height in centimetres and your current weight in kilograms.
- Choose the activity level that describes an average week.
- Set the weight you want to reach and the weekly pace you want to aim for.
- Click Calculate deficit to see your TDEE, daily calorie target and timeline to goal.
How the deficit is calculated
BMR (men) = 10×weight + 6.25×height − 5×age + 5 BMR (women) = 10×weight + 6.25×height − 5×age − 161 TDEE = BMR × activity factor Daily deficit = (weekly goal kg × 7700) ÷ 7 Daily calorie target = TDEE − daily deficit
The weekly loss is simply the deficit you set, and the time to goal is the remaining weight divided by that weekly rate.
Example
With the defaults — a 30-year-old male, 175 cm and 80 kg at moderate activity (multiplier 1.55) — the tool estimates a BMR of 1,749 kcal and a TDEE of about 2,711 kcal. Choosing a goal of 75 kg at a 0.5 kg/week pace gives a daily deficit of 550 kcal, a daily calorie target of about 2,161 kcal, and a timeline of about 10 weeks (roughly 2.3 months) to reach your target weight.
Common use cases
- Sustainable fat loss: set a moderate 0.5 kg/week deficit you can actually stick to.
- Event preparation: find out if you can realistically lose the amount you want before a date or a photoshoot.
- Setting a diet calorie budget: get a concrete daily number to build a meal plan around.
- Checking an aggressive goal: see why a 1 kg/week pace is hard to sustain long-term.
Pro tips
- Start at 0.5 kg/week: it is gentle enough to preserve muscle and stick with.
- Recheck as you lose: your TDEE drops with your weight, so recalculate every few weeks.
- Adjust from real data: if the scale is flat for two weeks, lower the intake slightly or move more.
- Don't crash-diet: big deficits raise the risk of muscle loss and rebound weight gain.
FAQ
What is a calorie deficit?
A calorie deficit is the gap between how many calories you burn in a day (TDEE) and how many you eat. Eating fewer than you burn forces your body to use stored fat, which produces weight loss.
How is TDEE calculated here?
We estimate BMR using the Mifflin-St Jeor equation from your age, gender, height and weight, then multiply by an activity factor (1.2–1.9) to get your daily burn.
How many calories equal one kilogram of fat?
Roughly 7,700 calories per kilogram (about 3,500 per pound). So a daily deficit of 550 calories produces around half a kilogram of weight loss per week.
What is a safe daily deficit?
A deficit of 300-500 calories a day (0.25-0.5 kg per week) is generally sustainable. Larger deficits risk muscle loss, nutrient deficiency and binge eating.
Should I eat below my BMR?
Mostly no. Eating well below your basal metabolic rate can slow your metabolism and risk muscle loss. It is usually better to stay above your BMR and move more instead.
Is a 7,700 calorie figure exact?
No — it is an approximation. Fat and lean mass are not stored in fixed 7,700-calorie blocks, so treat results as estimates and adjust to how your weight moves.
Does a deficit work without exercise?
Yes — diet alone creates a deficit. But exercise raises your TDEE, so you can eat more food while still losing weight, and it helps preserve muscle.
Why does my weight stall on a deficit?
As you lose weight your TDEE also drops, so the same intake becomes a smaller deficit. Water retention and hormonal shifts can also hide progress for a week or two.
Should I recalculate the deficit as I get lighter?
Yes. Recalculate every few weeks or after a significant weight change, because your maintenance level shrinks as you lose weight.
Is this calculator medical advice?
No. These are general estimates. For large deficits or medical conditions, please consult a dietitian or doctor.
Is this calorie deficit calculator free?
Yes. It runs entirely in your browser and nothing you enter is uploaded or stored.
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