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 from stored energy, mostly body fat, which is what makes the scale move down over time.

How big should my calorie deficit be?

For most people a deficit between 250 and 750 calories per day works well, with around 500 as the common middle ground. That corresponds to losing roughly 0.25 to 0.75 kg (0.5 to 1.5 lb) per week. Bigger deficits work faster but are much harder to sustain.

How many calories are in one kilogram of body fat?

Roughly 7700 calories per kilogram, or about 3500 per pound. That is why a daily deficit of about 550 calories loses close to half a kilogram per week: 550 times 7 is close to half of 7700.

How low can my daily calories safely go?

As a rule of thumb, most women should not eat below about 1200 calories per day and most men not below about 1500 without medical supervision. Under those floors it becomes very hard to get enough protein, vitamins, and minerals. If your target lands lower, choose a slower pace.

How fast can I lose weight without losing muscle?

Around 0.5 to 1 percent of your bodyweight per week is a widely used guideline. Keep protein high, keep lifting, and prefer the slower end of that range the leaner you get. Aggressive deficits cost more muscle, especially without resistance training.

Do I need to recalculate as I lose weight?

Yes. Maintenance calories drop as you get lighter, so a deficit that worked at the start slowly shrinks. Re-check your maintenance every 4 to 5 kg (about 10 lb) of loss, or whenever the scale stalls for two to three weeks, and set a fresh target.

Free calorie deficit calculator

Your goal weight,
with a date on it.

Pick how fast you want to lose, and see your daily calorie target, your daily deficit, and the date you reach your goal. Free, instant, no signup.

Units

Current weightkgGoal weightkg

Maintenance calorieskcal

Not sure of your maintenance calories? The TDEE calculator estimates them in under a minute.

Pace

At this pace you lose about 0.5 kg per week.

Your daily calorie target

1,850

kcal per day

77% of your 2,400 kcal maintenance stays on your plate.

Daily deficit: 550 kcal
Weeks to goal: 12
Projected finish: December 13, 2026

25% of the way: 82.5 kgOctober 11, 2026
50% of the way: 81.0 kgNovember 1, 2026
75% of the way: 79.5 kgNovember 22, 2026

Weight loss is rarely a straight line. The first two weeks usually move faster because of water, then the trend settles toward your chosen pace.

How to plan your calorie deficit

Enter your weights and maintenance calories, pick a weekly pace, and read your daily calorie target with a projected finish date.

1
Enter your weights and maintenance calories
Add your current weight, your goal weight, and your maintenance calories. The TDEE calculator can estimate maintenance if you do not know it.
2
Pick a weekly pace
Choose relaxed, steady, or aggressive. The pace sets how much weight you lose per week and how large your daily deficit is.
3
Read your target and your date
See the calories to eat each day, the weeks to your goal, and the projected date you arrive, with milestones along the way.

How the math works

A deficit is a plan, not a punishment.

The energy gap

One kilogram of body fat stores roughly 7700 calories, about 3500 per pound. Eat below your maintenance every day and your body covers the gap from stored fat.

Pace is a trade

A larger deficit reaches the goal sooner, but costs more hunger, less energy in training, and puts more muscle at risk. A smaller one is slower and far easier to keep.

The date does the motivating

A daily target with a finish date turns a vague wish into a countdown. Milestones at every quarter of the way keep the middle weeks honest.

Questions, answered

Calorie deficits, explained.

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 from stored energy, mostly body fat, which is what makes the scale move down over time.
How big should my calorie deficit be?: For most people a deficit between 250 and 750 calories per day works well, with around 500 as the common middle ground. That corresponds to losing roughly 0.25 to 0.75 kg (0.5 to 1.5 lb) per week. Bigger deficits work faster but are much harder to sustain.
How many calories are in one kilogram of body fat?: Roughly 7700 calories per kilogram, or about 3500 per pound. That is why a daily deficit of about 550 calories loses close to half a kilogram per week: 550 times 7 is close to half of 7700.
How low can my daily calories safely go?: As a rule of thumb, most women should not eat below about 1200 calories per day and most men not below about 1500 without medical supervision. Under those floors it becomes very hard to get enough protein, vitamins, and minerals. If your target lands lower, choose a slower pace.
How fast can I lose weight without losing muscle?: Around 0.5 to 1 percent of your bodyweight per week is a widely used guideline. Keep protein high, keep lifting, and prefer the slower end of that range the leaner you get. Aggressive deficits cost more muscle, especially without resistance training.
Do I need to recalculate as I lose weight?: Yes. Maintenance calories drop as you get lighter, so a deficit that worked at the start slowly shrinks. Re-check your maintenance every 4 to 5 kg (about 10 lb) of loss, or whenever the scale stalls for two to three weeks, and set a fresh target.

See what the scale cannot.

The physique rater scores every muscle group from photos, so you can watch your shape change while the weight comes down.

Rate my physique

Your goal weight,with a date on it.