Calorie Deficit Calculator

Eating fewer calories than your body burns in a day, so it makes up the difference from stored fat. A kilogram of body tissue holds roughly 7,700 kcal, which is why a steady 550 kcal daily deficit works out to about half a kilo a week.

The NHS advises losing 0.5 to 1 kg a week, which means a deficit of roughly 550 to 1,100 kcal a day. Smaller deficits are easier to stick to and keep more muscle, and consistency beats aggression over months. That's why our paces stop at 1 kg a week.

We don't plan faster than that, because the NHS advises against it: quicker losses cost more muscle, raise the risk of gallstones and nutrient shortfalls, and rebound harder. If you're carrying a lot of weight you'll often beat the plan in the early weeks anyway, mostly water, and that's normal. Anything genuinely faster belongs under medical supervision, and your GP can refer you to NHS weight management services.

Because we tell the truth. We never plan your calories below the safe floors, 1,500 for men and 1,200 for women, so if an aggressive pace would need fewer calories than that, we hold the floor, work out the pace you can actually achieve, and date the timeline from that real pace. Most calculators print the fantasy date instead.

No, the deficit does the losing. But activity raises what you burn, which means more food for the same pace, better muscle retention and an easier time sticking to it. Pick your real activity level above, not the one you aspire to.

As you lose weight your body burns less, so the same calories become a smaller deficit. Plateaus of a week or two are also normal water noise. Recalculate here every 2 to 3 kg, or use an app that adjusts the target for you automatically.

It's the floor we never plan below for women, 1,500 for men, in line with widely used safety minimums. Going lower than that belongs under medical supervision, not a website. If the calculator holds you at the floor, that's it protecting you, not a bug.

It runs on the same Mifflin-St Jeor engine as our TDEE calculator, uses the standard 7,700 kcal per kilogram convention, keeps every plan inside NHS pace guidance and safety floors, and dates your timeline from the pace you can genuinely hit rather than the one you clicked. Nothing you type is saved and there are no ads.

If you have a lot to lose, your GP can refer you to NHS weight management support. Speak to them first if you're on medication, managing a condition, or pregnant. And if eating or tracking ever starts to feel obsessive, step back and talk to someone, that matters more than any date on this page.