Calorie Deficit Calculator (Weight Loss)
Work out how many calories to eat each day to lose weight, your weekly rate of loss, and how many weeks it will take to reach your goal — with a safe, sustainable deficit.
Weight-Loss Plan
Calories to stay the same weight
Target Daily Calories
1700 kcal
0.45 kg/week → goal in ~11 weeks
Eat Per Day
1700 kcal
Weekly Weight Loss
0.45 kg
Time to Goal
11 weeks (77 days)
Total Energy Deficit
38,500 kcal
How It Works
Weight loss comes down to a calorie deficit: eating fewer calories than your body burns, so it draws on fat stores for the difference. About 7,700 kcal is stored in one kilogram of body fat, so a daily deficit of 500 kcal produces roughly 0.45 kg of loss per week (500 × 7 ÷ 7,700). This calculator takes your maintenance calories (your TDEE — what you burn in a day), the daily deficit you want to run, and how much weight you want to lose. It returns the target calories to eat each day, your expected weekly loss, and how long the goal will take. A safe, sustainable deficit is usually 300–750 kcal/day; larger deficits work faster but are harder to maintain and can cost muscle. Avoid going below about 1,200 kcal (women) or 1,500 kcal (men) without medical guidance.
Formula
Target calories = Maintenance − Deficit. Time = (kg to lose × 7,700) ÷ Deficit (days). Weekly loss = Deficit × 7 ÷ 7,700 kg.
Frequently Asked Questions
How big should my calorie deficit be?
A sustainable deficit is usually 300–750 kcal/day, giving about 0.25–0.7 kg of loss per week. Aggressive deficits lose weight faster but are harder to stick to and can reduce muscle and energy.
How many calories is 1 kg of fat?
Roughly 7,700 kcal. So to lose 1 kg you need a total deficit of about 7,700 kcal — for example, 500 kcal/day for around 15 days.
What is maintenance calories (TDEE)?
The number of calories that keeps your weight stable — your total daily energy expenditure. Eat below it to lose weight, above it to gain. Use our TDEE/BMR calculator to estimate yours.
Is very low-calorie dieting safe?
Going below about 1,200 kcal (women) or 1,500 kcal (men) can leave you short on nutrients and muscle, and is hard to sustain. Do it only under medical supervision.
Why has my weight loss stalled?
As you lose weight your maintenance calories fall, shrinking the deficit. You may need to recalculate your TDEE and adjust intake. Water retention and muscle gain can also mask fat loss.