Calorie Deficit Calculator
See how fast you'll lose weight from a calorie deficit. Enter your maintenance calories (TDEE) and how much you plan to eat each day, and this calculator shows your daily deficit plus your projected weekly and monthly weight loss — and how long it takes to drop each kilogram.
Formula
Deficit = TDEE − Target Calories
Weekly loss (kg) = Deficit × 7 / 7,700
- Your daily deficit is your maintenance calories (TDEE) minus what you actually eat.
- About 7,700 kcal equals roughly 1 kg of body fat, so weekly loss ≈ (daily deficit × 7) ÷ 7,700.
- A 500 kcal/day deficit is about 0.5 kg per week; 1,000 kcal/day is about 1 kg per week.
- If your intake is above your TDEE, you're in a surplus and will gain rather than lose.
- To find your TDEE first, use a TDEE or calorie calculator with your age, weight, height, and activity level.
- These are estimates — weigh yourself over 2–3 weeks and adjust intake if your actual loss differs.
TDEE 2,500, eating 2,000 kcal
Inputs
- Your TDEE (Maintenance Calories): 2500 kcal/day
- Target Daily Calories: 2000 kcal/day
Daily deficit = 2,500 − 2,000 = 500 kcal. Weekly loss ≈ (500 × 7) ÷ 7,700 ≈ 0.45 kg/week, or about 1 kg every 15 days.
Frequently asked questions
How big should my calorie deficit be?
A 500 kcal/day deficit (about 0.5 kg/week) is a common, sustainable target. Going beyond 1,000 kcal/day risks muscle loss, fatigue, and rebound eating.
Why 7,700 calories per kilogram?
One kilogram of body fat stores roughly 7,700 kcal of energy. Creating that much of a cumulative deficit is what's behind losing about a kilogram of fat.
Why am I not losing as predicted?
Estimates assume a steady TDEE and perfect tracking. Water retention, underestimated intake, and a metabolism that adapts as you lose can all slow progress — use the scale trend over weeks to recalibrate.
Is a bigger deficit always better?
No. Too large a deficit can cost you muscle, lower your energy, and make the diet hard to sustain. A moderate deficit you can stick with usually wins long term.
Can I lose weight without exercise?
Yes — the deficit drives fat loss, and you can create it through diet alone. Exercise raises your TDEE so you can eat a bit more, and it helps preserve muscle.
Related calculators
TDEE Calculator Calculate your Total Daily Energy Expenditure (TDEE) — the total calories you burn in a day including exercise. This is your maintenance calorie number. Calorie Calculator Find out how many calories you need each day to lose, maintain, or gain weight. This calculator estimates your BMR with the Mifflin-St Jeor equation, multiplies by your activity level to get your maintenance calories (TDEE), then adjusts for your goal so you get a daily calorie target you can actually eat to. Weight Loss Percentage Calculator Weight Loss Percentage Calculator is a health and wellness calculator that helps you calculate a percentage from a part and a whole, or a percentage change. The formula used is: Weight Loss % = ((Starting Weight − Current Weight) / Starting Weight) × 100. Enter values using the units shown next to each input field (e.g. kg, cm, years).