How a calorie deficit works
You lose weight when you eat fewer calories than your body burns — a calorie deficit. Your daily target = maintenance calories − deficit. Because about 3,500 calories equals one pound of fat, a 500-calorie daily deficit adds up to roughly 1 lb (0.45 kg) of loss per week. From a 2,500 maintenance, a 500 deficit means eating 2,000 a day.
How to use this calculator
Enter your maintenance calories (find them with the maintenance calorie calculator) and the daily deficit you want. The result shows your daily target and the estimated weekly weight loss in pounds and kilograms. Never plan a target below the floor shown by the BMR calculator.
Choose a safe, sustainable deficit
A moderate deficit of about 300–500 calories a day (up to roughly 1% of body weight per week) is sustainable and protects muscle. Avoid eating below about 1,200–1,500 calories a day without medical supervision — very low intakes are hard to sustain, can cost you muscle, and may be unsafe. Slower is steadier. Once you have the calorie target, split it into protein, carbs and fat with the macro calculator.
Why the scale isn't linear
Weight loss rarely tracks the math exactly. Water, sodium, glycogen and hormones cause day-to-day swings, and metabolism adapts as you lose. Use the weekly trend, not a single weigh-in. This tool is a general estimate for information only, not medical or nutrition advice.
Frequently asked questions
- How do I calculate a calorie deficit?
- Subtract your chosen deficit from your maintenance calories. A 500-calorie deficit from a 2,500 maintenance means eating 2,000 a day, for about 1 lb of loss per week.
- How big should my calorie deficit be?
- A moderate 300–500 calories a day is sustainable for most people. Avoid going below about 1,200–1,500 total calories without medical guidance.
- How much is one pound of fat in calories?
- Roughly 3,500 calories, which is why a 500-a-day deficit loses about a pound a week.
- Why am I not losing as fast as the math says?
- Water, sodium and hormonal shifts mask fat loss day to day, and metabolism adapts. Track the weekly trend instead of single weigh-ins.
- What if my deficit is bigger than my maintenance calories?
- Then the target is not usable. A deficit should be a slice of maintenance, not most of it, so if the daily target falls under roughly 1,200-1,500 calories, reduce the deficit. This is a general estimate, not medical advice.