How this calculator works
It works out how many calories you burn in a day with the Mifflin-St Jeor equation and your activity level, then takes off a daily deficit: 250 calories for a gentle pace, 500 for a steady one, or 750 for a faster one. A pound of body fat holds about 3,500 calories, so a 500-calorie deficit is about a pound (0.45 kg) a week.
It assumes you keep the same deficit all the way, which means eating a little less as you get lighter, so it shows two numbers: your calories at the start and at your goal. Real progress goes up and down from week to week, so look at your weekly average instead of any single weigh-in.
Once you know your calories, our free Macro, TDEE & BMR Calculator can split them into protein, carbs and fat for you.
Common questions
How long will it take to lose 20 pounds?
At a steady pace of about a pound a week, it takes around 20 weeks, or about five months. A gentle pace takes about twice as long.
How fast is too fast?
Losing more than about 1% of your body weight a week makes it harder to keep your muscle and stick with the plan. If the calculator flags your pace, try the next slower option.
Why does my progress slow down?
As you get lighter, your body burns fewer calories, so eating the same amount gives you a smaller deficit. If you recalculate every 10 to 15 lb (4.5 to 7 kg), your deficit stays on track. Your weight can also swing a few pounds from day to day with water, so your weekly average is a better guide. See How much water is enough?
For more, see How to count calories to lose weight.
