Calorie Deficit and Weight Loss Time Calculator
Enter your weight and goal, then plan by a target date, a weekly loss or a daily calorie gap. Add the calories you use to see what to eat.
This is an estimate for general information and is not medical advice. Use the calorie calculator if you do not know the calories you use. Speak to your GP or a dietitian before eating much less than usual.
Worked examples
7 kg in 70 days
Lose 7 kg in 70 days, using 2,500 kcal a day
Gap 770 kcal, eat 1,730 kcal, 0.7 kg a week
7 x 7,700 / 70.
10 kg at 500 kcal a day
Lose 10 kg with a daily gap of 500 calories
22 weeks
10 x 7,700 / (500 x 7).
About Calorie Deficit and Weight Loss Time Calculator
A calorie deficit means eating fewer calories than your body uses, and the size of the gap decides how quickly weight changes. This calculator works whichever way round suits you. Give it a target date and it tells you the daily gap needed. Or give it a weekly loss, or a daily gap, and it tells you how many weeks it will take and the date you would arrive.
It uses about 7,700 calories per kilogram of body weight (about 3,500 per pound). If you enter the calories you use in a day, it subtracts the gap to show how much to eat. It also shows the weekly loss your plan implies and comments if that is faster than the 0.5 to 1 kg (1 to 2 lb) a week the NHS suggests. Real progress slows as you get lighter. This is an estimate and not medical advice.
How to use Calorie Deficit and Weight Loss Time Calculator
- Choose metric or imperial units, then enter your current and goal weights.
- Choose how to plan: by a target date, a weekly loss or a daily calorie gap, and enter it.
- Add the calories you use in a day if you would like the calories to eat.
- Read the daily gap, the weekly loss, the weeks to goal and the date.
Common uses
- Planning around a wedding or holiday date
- Checking if a deadline is realistic
- Seeing how long a 500 calorie gap takes
- Finding calories to eat for a chosen pace
Frequently asked questions
How big a calorie deficit is reasonable?
Many people use about 500 calories a day, which leads to roughly 0.45 kg a week. The NHS suggests 0.5 to 1 kg (1 to 2 lb) a week. Bigger gaps are harder to keep up.
How is the time worked out?
The weight to lose is multiplied by 7,700 calories per kilogram and divided by the weekly calorie gap. A daily gap of 500 calories is 3,500 a week, so losing 10 kg takes about 22 weeks.
Where do I get the calories I use?
Use the calorie calculator. It multiplies your resting energy by an activity level. Treat it as a starting figure and adjust after a few weeks of tracking.
Why will real life be slower?
As you lose weight your body uses less energy, so the same gap produces less loss. Water, hormones and eating out also move the scale around. Plan for plateaus and allow some extra weeks.
Is this medical advice?
No. It is an estimate and not medical advice. Speak to your GP or a dietitian before eating much less than usual, particularly if you have a medical condition, take medicine, are pregnant or are under 18.