EZ Calculators

Calorie Deficit Calculator

This calorie deficit calculator compares your maintenance calories (TDEE) with what you plan to eat. Enter an intake, a daily deficit or a weekly pound or kilogram figure. You'll see the daily gap, its share of your TDEE, weekly and period totals, and a side-by-side table of deficit sizes.

Calculation and content reviewed by EZ Calculators Editorial Team on .

Enter values

Compare an entered adult maintenance estimate with planned intake or an energy-gap assumption. Static pound and kilogram shorthand stays separate from dynamic body-weight prediction.

Build the scenario below, then calculate for a complete result report.

Runs in your browser
Maintenance valueEntered by user
Comparison modelThree explicit modes
Weight forecastNot calculated
Choose what you want to compare

Each mode arrives at the same daily energy-gap ledger from a different starting assumption.

Set the comparison baseline

Use an adult maintenance estimate you already have and choose how many weeks of energy arithmetic to display. Error in TDEE carries into every result.

Adult comparison
Enter a measured or estimated adult TDEE. Any error in this starting value carries into every result.
kcal/day
The period totals energy arithmetic only; it does not project body weight.
weeks

Enter planned intake

The result subtracts planned intake from entered TDEE. It does not approve or prescribe the intake.

Compare planned intake
This is compared with TDEE; it is not approved or prescribed by the calculator.
kcal/day
Energy arithmetic, not a body-weight promise

Body mass, energy expenditure, water, and tissue composition change over time. This page never turns a static energy total into predicted future weight or a prescribed diet.

How many calories should I eat to lose weight?

Start from your maintenance calories (TDEE) and subtract a deficit. A 2013 U.S. obesity guideline describes a deficit of 500 or 750 kcal a day. If your TDEE is 2,400 kcal, a 500 kcal deficit means eating about 1,900 a day. Treat it as a starting point and adjust from your weight trend over several weeks.

How to use the calorie deficit calculator

You need a maintenance estimate first. This calculator doesn't work out your TDEE from your body size, so get that number from our TDEE calculator, a tracking app or your own food-and-weight trend.

Then pick the mode that matches the number you already have. All three show the same kind of result: your daily gap, weekly gap, period total and the gap as a share of TDEE.

  1. Enter your estimated maintenance calories (TDEE) between 1,000 and 8,000 kcal a day.
  2. Choose Compare planned intake if you know what you plan to eat.
  3. Or choose Set a daily energy gap if you know the deficit you want, such as 500.
  4. Or choose weekly-change shorthand to convert lb or kg per week into a daily gap.
  5. Set a period from 1 to 52 weeks and calculate.

Calorie deficit formula

The math is simple subtraction. The hard part is that both inputs are estimates. If your real TDEE is 200 kcal higher or lower than what you entered, your real deficit moves by the same 200.

The pound and kilogram figures use the familiar 3,500 kcal per pound and 7,700 kcal per kilogram conversions. The calculator labels them as shorthand, because your body doesn't follow that rule exactly over time.

Formula guide
  • Daily deficit = TDEE - planned intake
  • Planned intake = TDEE - daily deficit
  • Weekly deficit = daily deficit x 7
  • Deficit as % of TDEE = daily deficit / TDEE x 100
  • Shorthand lb per week = weekly deficit / 3,500
  • Shorthand kg per week = weekly deficit / 7,700

Worked example: 2,400 kcal TDEE

Say your TDEE is 2,400 kcal a day and you plan to eat 1,900. That's a 500 kcal daily gap, or 20.83% of your TDEE. Over a week it's 3,500 kcal. Over eight weeks it's 28,000 kcal. By the shorthand, that's 1.00 lb or about 0.45 kg a week.

The calculator also lays out the same TDEE at five deficit sizes, so you can see the trade-offs without retyping anything.

Deficit sizes at a 2,400 kcal TDEE
Deficit (% of TDEE)Daily deficitPlanned intakeWeekly deficit
5%120 kcal2,280 kcal840 kcal
10%240 kcal2,160 kcal1,680 kcal
15%360 kcal2,040 kcal2,520 kcal
20%480 kcal1,920 kcal3,360 kcal
25%600 kcal1,800 kcal4,200 kcal

Calorie deficit for weight loss: how much?

The 2013 AHA/ACC/TOS guideline on managing overweight and obesity in adults lists a 500 or 750 kcal a day deficit as one way to set a reduced-calorie diet. At a 2,400 kcal TDEE, 750 a day means eating 1,650, a weekly gap of 5,250 kcal or 1.5 lb by the shorthand.

CDC describes gradual loss of about 1 to 2 pounds a week as more likely to last than faster loss. The same 500 kcal is a bigger bite out of a smaller TDEE: 25% of 2,000 kcal but only about 16.7% of 3,000. Pick a size you can keep up, and get advice from a clinician if you're unsure.

Why the 3,500-calorie rule overstates loss

The rule assumes your energy use stays the same as you lose weight. It doesn't. Research by Kevin Hall and colleagues at NIH shows that as you get lighter, you burn less, so a fixed deficit produces slower loss over time than the rule predicts.

That's why this calculator shows energy totals, not a goal date or future weight. For a time-based forecast, the NIDDK Body Weight Planner uses a dynamic model built on that research.

Why the scale doesn't match the math

Day to day, your weight moves with water, salt, stored carbohydrate, food in your gut and, for many women, the menstrual cycle. A week in a deficit can still show a higher number. Early drops can also be bigger than real fat loss.

Look at a multi-week trend under the same conditions. If it doesn't match your plan, check your TDEE source and your food logging before cutting further. Don't add a smartwatch's exercise calories to a TDEE that already includes your activity, or you'll count it twice.

Safety limits

This is arithmetic, not a diet plan. The calculator won't accept an intake below 1,000 kcal a day, which matches the floor in the NIDDK Body Weight Planner. That isn't a safe minimum for you. Intakes above it can still be too low.

Don't use this page for children or teens, pregnancy or breastfeeding, eating disorders or a history of them, or medical conditions and medications that affect weight. Very low-calorie diets need medical supervision. Stop tracking and get support if it causes distress, dizziness, constant hunger or other symptoms.

Sources

These government sources, guidelines and studies back up the deficit sizes, weekly pace and modeling limits on this page.

AHA/ACC/TOS 2013 obesity guideline summary (ACC)Lists the 500 or 750 kcal daily deficit option for adults.CDC: steps for losing weightCDC guidance on gradual weight loss of 1 to 2 pounds a week.NIDDK: Body Weight PlannerNIH's dynamic tool for planning intake and weight over time.Hall and Chow on the 3,500-calorie ruleWhy the static 3,500 kcal per pound rule overpredicts weight loss.Hall et al.: dynamic adult body-weight modelThe model behind NIDDK's Body Weight Planner.NIDDK: choosing a safe and successful weight-loss programWhat to look for in a safe weight-loss plan.

FAQ

How do I calculate my calorie deficit?

Subtract what you plan to eat from your TDEE. With a 2,400 kcal TDEE and a 1,900 kcal intake, your deficit is 500 kcal a day, or 3,500 kcal a week.

Is a 500 calorie deficit good?

It's a common starting point. A 2013 adult obesity guideline lists 500 or 750 kcal a day as options. Whether it suits you depends on your size, health and how sustainable it feels.

How much weight will I lose in a 500 calorie deficit?

The old shorthand says 1 lb a week, but real loss usually slows over time because your body burns less as you get lighter. Use the NIDDK Body Weight Planner for a time-based estimate.

Why am I not losing weight in a calorie deficit?

Your TDEE estimate may be too high, logging can miss food, and water shifts can hide fat loss for a week or two. Check a multi-week trend before cutting further.

Should I eat back exercise calories?

Not if your TDEE already includes your activity level. Adding a watch's workout calories on top counts that activity twice and shrinks your real deficit. Pick one way to count activity and stick with it.

Why won't the calculator go below 1,000 calories?

It matches the minimum intake the NIDDK Body Weight Planner accepts. That isn't a personal safe minimum, and intakes above it can still be too low for you. Very low intakes need medical supervision.

What is 500 calories a day in kilograms?

By the 7,700 kcal per kilogram shorthand, a 500 kcal daily deficit is 3,500 kcal a week, or about 0.45 kg. Real loss over time is usually lower than that.