Calorie deficit calculator
How much to eat to lose weight at a steady pace, and how many weeks it would take. Free, and no sign-up needed.
14-day free trial. FuelKey turns your numbers into real meals and a daily checklist.
See how FuelKey worksHow it works
1. What you burn
Your resting burn (Mifflin-St Jeor) times how active your job is, plus a little for each training day.
2. Your deficit
About 500 calories a day under that for each pound a week you want to lose.
3. Weeks to goal
The pounds between you and your goal weight, divided by your pace.
How big should a deficit be?
For most people, a pace of about 0.5 to 1% of bodyweight a week works: fast enough to see progress, slow enough to keep muscle and keep going. Faster than that tends to cost muscle and gets hard to stick with.
The calculator warns you if your target would drop below 1,200 calories for women or 1,500 for men, the lowest intakes generally considered safe without medical supervision.
Common questions
Is 500 calories a day really a pound a week?
It's a good rule of thumb: about 3,500 calories is roughly a pound of body fat. Real weight moves less evenly than that, because water and food weight go up and down day to day. Judge it by your trend over two to three weeks.
Why might it take longer than the weeks shown?
As you lose weight you burn a little less, so the same intake makes a slightly smaller deficit. FuelKey's weekly review adjusts your target from your actual trend so you don't stall.
Should I eat more protein while losing?
Yes. Higher protein helps keep muscle while you're eating less. The protein calculator works out a daily goal for you.
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Not medical or dietary advice. These are estimates from standard formulas. If you are pregnant, under 18, have a medical condition or take medication that affects appetite or weight, check with your doctor before changing how you eat.