Focal

Free tool

Calorie deficit calculator

Work out a daily calorie deficit from your maintenance calories. Choose a gentle, steady or faster cut, see the weekly pace, and keep fat loss sustainable.

years
cm
kg
Activity level
Deficit pace

Fill in your age, height and weight to see a calorie deficit target. Everything is calculated on this page; nothing is stored or sent anywhere.

How a calorie deficit calculator works

This tool estimates your maintenance calories with the Mifflin-St Jeor equation and standard activity multipliers, then subtracts the deficit you choose. That is the same approach used by most maintenance calorie calculators, with the fat-loss step built in.

Enter weight in kilograms or UK stone and pounds. Height can be cm or feet and inches. Nothing is stored; the maths runs in your browser.

Picking a deficit you can keep

A 250 kcal cut is easier to live with and suits longer fat-loss phases. A 500 kcal cut is the usual default for noticeable weekly change. A 750 kcal cut is faster but demands more planning around protein, sleep and training. If gym performance collapses or hunger becomes constant, reduce the cut rather than forcing it.

  • Gentle: about 0.25 kg a week
  • Steady: about 0.5 kg a week
  • Faster: about 0.75 kg a week

From deficit to protein and macros

Calories decide the rate of loss; protein decides how much of that loss is fat versus muscle. After you have a daily calorie target, set protein with the protein intake calculator, then optionally split the rest of your calories with the macro calculator.

How to check the plan is working

Weigh yourself a few mornings a week under similar conditions and watch the trend over two to three weeks, not day-to-day noise. If the average is flat, trim another 100 to 200 kcal or add a little activity. If the drop is steeper than you want, raise calories toward maintenance.

Common questions

What is a calorie deficit?
A calorie deficit means eating fewer calories than your body burns in a day. Your body makes up the difference by using stored energy, which is why a consistent deficit leads to fat loss over time. The size of the deficit decides how quickly that happens.
How do I calculate a calorie deficit?
First estimate your maintenance calories (TDEE) from sex, age, height, weight and activity. Then subtract 250 to 500 kcal for a sustainable cut, or up to about 750 kcal if you prefer a faster pace and can keep protein high. This calculator does that in one step.
How big should my calorie deficit be?
Most people do best with 250 to 500 kcal below maintenance, roughly 0.25 to 0.5 kg a week. Larger deficits can work short-term but are harder to stick to and raise the risk of losing muscle, especially if protein and training drop.
Is a 500 calorie deficit good for weight loss?
Yes. A 500 kcal daily deficit is the classic sustainable target and usually lands around 0.5 kg a week. If energy, training or adherence suffer, step down to 250 kcal and give it two to three weeks before judging.
How many calories should I eat to lose weight?
Start from maintenance, then choose a deficit. Someone who maintains at 2,400 kcal might eat about 1,900 kcal for a steady cut or 2,150 kcal for a gentler one. Floor targets at 1,200 kcal in this calculator so results stay in a safer range for most adults.
Do I need a calorie deficit every day?
Weekly average matters more than any single day. Many people keep a steady daily target; others eat a bit more on hard training days and a bit less on rest days. Either approach works if the weekly average stays below maintenance.
Will a calorie deficit slow my metabolism?
Long, aggressive deficits and large weight drops can lower daily burn a little through less body mass and adaptive changes. A moderate deficit, enough protein, resistance training and occasional diet breaks help keep progress steadier.
Should I combine a deficit with high protein?
Yes. Higher protein (often 1.8 to 2.4 g per kg while dieting) helps preserve muscle and keeps you fuller. Pair this tool with the protein calculator, then track both calories and protein in an app if you can.

More free tools

Make the deficit automatic

Focal sets your calorie target and logs meals by photo, barcode or voice so you can see the deficit closing in real time.

Download on the App Store
Soon