Calorie Deficit Calculator for Weight Loss
Set your deficit, see the exact calories to eat each day, and watch a 12-week projection of your weight loss update in real time.
Your details
How your deficit is built
12-week weight projection
Estimated progress at this deficit (7,700 kcal ≈ 1 kg).
A calorie deficit is the foundation of every weight-loss plan: eat fewer calories than your body burns, and it makes up the difference from stored fat. This calculator finds your maintenance calories (your TDEE), subtracts the deficit you choose, and projects how your weight is likely to change over the next twelve weeks — all based on the well-established estimate that a pound of fat holds roughly 3,500 calories (about 7,700 per kilogram).
How a calorie deficit drives weight loss
Your body needs a certain number of calories each day just to function and move around — that's your TDEE. Eat below it and you create a deficit; your body covers the shortfall by burning fat and, if the deficit is too aggressive, some muscle too. A deficit of about 500 calories a day is the classic sweet spot, producing roughly one pound (0.45 kg) of loss per week while staying comfortable enough to sustain.
The Energy Flow diagram shows how your deficit is built from your BMR and activity, and the projection line turns that daily number into a week-by-week forecast. Change your deficit and both update instantly so you can find a pace that fits your life.
How big should your deficit be?
A mild deficit of 250 calories suits people who are already lean or want to protect muscle and performance. A 500-calorie deficit is the standard recommendation for steady, sustainable loss. A 1,000-calorie deficit produces faster results but is harder to maintain and only appropriate for those with more weight to lose.
Whatever you choose, this tool won't let your target fall below 1,200 calories a day for women or 1,500 for men. Very low intakes are difficult to stick to, tend to leave you under-nourished, and often cost you lean muscle — the opposite of what most people want.
Frequently Asked Questions
Eat about 500 calories below your TDEE for steady weight loss of roughly one pound per week. Use the calculator above to get your personalised number based on your age, sex, height, weight, and activity level.
As a rule of thumb, a 500-calorie daily deficit produces about one pound (0.45 kg) of fat loss per week, and a 1,000-calorie deficit about two pounds. Real results vary with water weight, muscle, and adherence, so track your average weight over two to three weeks.
A 1,000-calorie deficit can be appropriate for people with more weight to lose, but it's aggressive and harder to sustain. This calculator never drops your target below 1,200 calories (women) or 1,500 (men). If you'd need to eat less than that, choose a smaller deficit or speak to a professional.
As you lose weight, your body becomes smaller and burns fewer calories, so the same intake becomes a smaller deficit. Recalculate every few weeks with your new weight to keep progress steady.
Not if your activity level is set correctly — your TDEE already includes typical exercise. Only add calories back if you selected a low activity level but trained much harder than usual.
These results are estimates for general educational purposes only and are not medical or nutritional advice. Individual needs vary. Consult a qualified healthcare professional or registered dietitian before making significant changes to your diet, especially if you are pregnant, breastfeeding, under 18, or have a medical condition.