# What is my calorie deficit?

Works out the daily calorie deficit and intake to lose a chosen weight each week: TDEE (BMR × activity factor) minus the rate × 3,500 calories per pound ÷ 7.

- Page: https://www.acalculator.org/health/calorie-deficit-calculator
- JSON spec: https://www.acalculator.org/health/calorie-deficit-calculator.json
- Version: a5f66ef251ee

## Default answer

Example with the default inputs (Sex Female, Age 30, Height 5 ft 5 in, Weight 150 lb, Activity Light: exercise 1 to 3 days, BMR formula Mifflin-St Jeor, Weight to lose each week 1 lb): Eat about 1,427 calories a day for your weekly goal: a deficit of 500 from your 1,927.

## Inputs

| Key | Label | Description |
| --- | --- | --- |
| sex | Sex | Sex at birth, which the body formulas use. |
| age | Age | Your age in whole years. |
| height | Height | Your height without shoes. |
| weight | Weight | Your body weight. |
| activity | Activity | How active you are in a usual week, which sets the multiplier on your BMR. |
| formula | BMR formula | The equation for basal metabolic rate: Mifflin-St Jeor (1990) or the revised Harris-Benedict (1984). |
| rate | Weight to lose each week | How much weight you want to lose each week. |

## Outputs

| Key | Label | Description |
| --- | --- | --- |
| target | Eat this many calories a day | Daily calories to lose the chosen weight each week: TDEE − daily deficit. |
| deficit | Daily calorie deficit | Calories a day under your TDEE: weekly loss in lb × 3,500 ÷ 7. |
| tdee | Calories to keep your weight (TDEE) | Total daily energy expenditure: BMR × activity factor. |
| share | Deficit as a share of TDEE | The daily deficit as a percentage of TDEE. |
| limit | Note | A warning when the daily target is below the lowest intake the weight-loss guideline suggests. |

## Method

Daily target = TDEE − weekly loss (lb) × 3,500 ÷ 7, with TDEE = BMR × activity factor and BMR from Mifflin-St Jeor or the revised Harris-Benedict.

## Assumptions

- A pound of body weight is taken as 3,500 calories (7,716 calories a kilogram). Real loss slows over time as your needs fall.
- TDEE is worked out at your current weight. Enter your new weight every few weeks.
- Activity factors: sedentary 1.2, light 1.375, moderate 1.55, very active 1.725, extra active 1.9.
- A target under 1,200 calories a day (women) or 1,500 (men) is shown with a warning: the low end of the diets in the 2013 AHA/ACC/TOS guideline.
- This is an estimate for planning, not medical advice.

## Worked examples

1. sex = female, age = 30, height = 1.651, weight = 68.038856, activity = light, formula = mifflin, rate = 0.453592 gives deficit = 500, target = 1,426.737388, tdee = 1,926.737388, share = 25.950605%. Source: Mifflin et al. 1990; 3,500 kcal per lb (Wishnofsky 1958); hand calculation in content.mdx.
2. sex = male, age = 45, height = 1.8, weight = 100, activity = moderate, formula = mifflin, rate = 0.5 gives tdee = 2,952.75, deficit = 551.155655, target = 2,401.594345, share = 18.665842%. Source: Mifflin et al. 1990; 3,500 kcal per lb = 7,716.2 kcal per kg; hand calculation in content.mdx.
3. sex = female, age = 50, height = 1.6, weight = 70, activity = sedentary, formula = mifflin, rate = 0.907185 gives tdee = 1,546.8, deficit = 1,000, target = 546.8, limit = This is under 1,200 calories a day, below the lowest diet the weight-loss guideline suggests. Choose a slower rate or ask a doctor.. Source: Mifflin et al. 1990; AHA/ACC/TOS 2013 guideline (1,200 kcal a day for women); hand calculation in content.mdx.

## FAQ

### What is a calorie deficit?

A calorie deficit is eating fewer calories than you burn. Your body makes up the difference from its stores, so you lose weight. The calories you burn in a day are your total daily energy expenditure (TDEE), which this calculator estimates from your BMR and activity level.

### How big a calorie deficit do I need to lose 1 pound a week?

About 500 calories a day. A pound of body weight is taken as 3,500 calories, and 3,500 ÷ 7 days = 500 calories a day. For 2 pounds a week the deficit is 1,000 calories a day; for 0.5 kg a week it is about 551.

### What is a safe calorie deficit?

The 2013 guideline from the American Heart Association, the American College of Cardiology and The Obesity Society suggests a deficit of 500 to 750 calories a day, or diets of 1,200 to 1,500 calories a day for women and 1,500 to 1,800 for men. The CDC notes that losing about 1 to 2 pounds a week makes it more likely you keep the weight off. The calculator warns you when your target is under 1,200 (women) or 1,500 (men) calories a day.

### Why am I losing weight more slowly than the calculator says?

The 3,500-calorie rule works for the first weeks but overestimates loss over months. As you lose weight your body burns fewer calories, so the same intake gives a smaller deficit. Studies found the rule can overestimate loss a lot over a year. Enter your new weight every few weeks, or use the weight loss calculator, which allows for this.

### Should I cut calories or exercise more?

Both change the deficit. Exercise raises your TDEE, and eating less lowers your intake. If you start exercising more, choose a higher activity level here so your TDEE and target calories go up to match.

### How is the deficit worked out in kilograms?

The same way. 3,500 calories per pound is about 7,716 calories per kilogram (3,500 ÷ 0.45359237). Losing 0.5 kg a week needs 0.5 × 7,716 ÷ 7 = 551 calories a day.

## Sources

- Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr. 1990;51(2):241-247. https://doi.org/10.1093/ajcn/51.2.241
- Roza AM, Shizgal HM. The Harris Benedict equation reevaluated: resting energy requirements and the body cell mass. Am J Clin Nutr. 1984;40(1):168-182. https://doi.org/10.1093/ajcn/40.1.168
- FAO/WHO/UNU. Human energy requirements (2004), section 5.3.1, Classification of physical activity levels (PAL = TEE ÷ BMR). https://www.fao.org/4/y5686e/y5686e07.htm
- Wishnofsky M. Caloric equivalents of gained or lost weight. Am J Clin Nutr. 1958;6(5):542-546. https://doi.org/10.1093/ajcn/6.5.542
- Thomas DM, et al. Can a weight loss of one pound a week be achieved with a 3500-kcal deficit? Commentary on a commonly accepted rule. Int J Obes. 2013;37(12):1611-1613. https://doi.org/10.1038/ijo.2013.51
- Jensen MD, Ryan DH, Apovian CM, et al. 2013 AHA/ACC/TOS Guideline for the Management of Overweight and Obesity in Adults. Circulation. 2014;129(25 Suppl 2):S102-S138. https://pmc.ncbi.nlm.nih.gov/articles/PMC5819889/
- Centers for Disease Control and Prevention. Steps for Losing Weight. https://www.cdc.gov/healthy-weight-growth/losing-weight/index.html