Calorie Deficit Calculator
Estimate a daily calorie target, weekly deficit and rough weight-change pace using cautious UK-friendly guidance.
Calculate your calorie deficit
Enter your estimated maintenance calories and planned deficit to see your daily target and a rough weekly pace.
This is a rough daily calorie target based on your selected deficit.
How this calorie deficit calculator works
A calorie deficit means your average calorie intake is below the energy your body uses over time. The calculator starts with your maintenance calories, subtracts your planned food deficit, then estimates a rough weekly pace.
Use the result as a planning guide, not a rule. Hunger, activity, sleep, health conditions, food tracking and normal water-weight changes can all affect the real result.
Calorie deficit formula
The calculator uses a simple energy-balance estimate.
Daily target calories = maintenance calories − food deficit
Weekly deficit = daily total deficit × 7
Estimated kg per week = weekly deficit ÷ 7,700
Estimated weeks to target = target kg ÷ estimated kg per weekThe 7,700 kcal per kg figure is only a rough conversion. It does not mean weight loss will happen in a perfectly straight line.
What is a safe calorie deficit?
For many adults, a smaller deficit is easier to keep up than an aggressive one. NHS Better Health says reducing intake by around 600 calories a day can be a safe and sustainable way to lose weight for many people, but that does not make it right for everyone.
Be especially cautious if you are pregnant, breastfeeding, under 18, have a history of disordered eating, have a medical condition, take medication that affects appetite or weight, or feel unwell while dieting.
Worked examples
Why the result may be wrong
Calorie estimates are not precise. Your true TDEE may be higher or lower than a calculator predicts, and calorie labels, portion sizes and activity trackers can all introduce errors.
If progress stalls, do not rush to cut calories sharply. It is usually better to review food tracking, activity, sleep and consistency over a few weeks before making changes.
What to use next
Calorie deficit FAQs
What is a calorie deficit?
It means eating and drinking fewer calories than your body uses over time. A deficit can support weight loss, but the size and sustainability of the deficit matter.
Is a 600 calorie deficit safe?
It can be a general starting point for many adults, but not for everyone. Very active people, smaller adults, pregnant or breastfeeding people, young people and anyone with a medical concern should get professional advice.
Can this calculator tell me exactly how much weight I will lose?
No. It gives a rough estimate using a simple calorie model. Real weight changes vary because of water, digestion, activity, hormones, sleep and tracking accuracy.
Should I include exercise calories?
You can, but use caution. Exercise trackers can overestimate calorie burn, and eating back every estimated exercise calorie may reduce the actual deficit.
Related health terms
Build the rest of your plan carefully
Once you know your calorie target, use the macro and protein calculators to make the number more practical — without turning it into medical advice.
Calculatorz may earn a commission from some links. Health and body results are estimates only and are not medical advice.