To lose weight you need a calorie deficit — eating slightly less than your body burns. But how many calories should you actually eat? The free calorie deficit calculator below works out your maintenance calories using the trusted Mifflin-St Jeor equation, then shows you exactly how much to eat for steady, healthy weight loss.

What is a calorie deficit?

A calorie deficit means you take in fewer calories than your body uses in a day. When that happens, your body makes up the difference by burning stored fat, and you lose weight. The calculator above first estimates your maintenance calories (also called your TDEE, or total daily energy expenditure), then subtracts a sensible amount so you lose weight at a steady pace.

How big should your calorie deficit be?

Roughly 7,700 calories equals about 1 kg (2.2 lb) of body fat. So a deficit of about 550 calories a day leads to around 0.5 kg (1 lb) of fat loss per week, which most experts consider a safe and sustainable rate. A larger deficit sheds weight faster but is harder to stick to and can cost you muscle. It is best not to eat below about 1,200 calories a day for women or 1,500 for men without medical supervision.

Tips for sticking to a calorie deficit

Fill up on protein and high-fibre foods so you feel satisfied on fewer calories, drink plenty of water, and do not cut too hard too fast. Track your intake honestly for a couple of weeks to learn portion sizes, and weigh yourself at the same time each week rather than daily, since water weight fluctuates. Pairing your deficit with strength training helps you keep muscle while you lose fat.

Frequently asked questions

How many calories should I eat to lose weight?

Eat about 500 to 550 calories a day below your maintenance level to lose roughly 0.5 kg (1 lb) a week. Use the calculator above to get your personal maintenance number, then pick the weight-loss target that suits you.

Is a 1,200 calorie diet safe?

1,200 calories is the usual lower limit for women (about 1,500 for men). Going lower can leave you short on nutrients and is only advisable under medical supervision. Most people lose weight comfortably on a smaller, more sustainable deficit.

Why am I not losing weight in a calorie deficit?

The most common reasons are underestimating portions, eating back exercise calories, or a target that is only a small deficit. Track intake carefully for two weeks, be consistent, and remember that water weight can hide fat loss on the scale.