Calorie Deficit Calculator

Use the Calorie Deficit Calculator to estimate your daily calorie needs, maintenance calories, and a calorie target based on your desired deficit.

The calculator estimates your basal metabolic rate (BMR), adjusts it for activity to estimate total daily energy expenditure (TDEE), and then subtracts the selected calorie deficit.

These calculations are estimates and should not be treated as individualized medical advice.

Calorie Deficit Calculator

Enter:

• Age
• Sex
• Height
• Weight
• Activity level
• Desired calorie deficit

The calculator can estimate:

• BMR
• Maintenance calories
• TDEE
• Daily calorie deficit
• Suggested daily calorie intake
• Estimated weekly calorie deficit
• Approximate weight-loss rate

What Is a Calorie Deficit?

A calorie deficit occurs when you consume fewer calories than your body uses over time.

For example, if your estimated daily energy expenditure is:

2,400 calories/day

and you consume:

1,900 calories/day

your estimated daily deficit is:

2,400 − 1,900 = 500 calories/day

A sustained energy deficit can lead to weight loss, although actual weight changes are affected by factors beyond a simple calorie calculation.

How the Calorie Deficit Calculator Works

The calculation has three main stages:

BMR → TDEE → Calorie Target

Step 1: Estimate BMR

BMR is an estimate of the energy your body requires at rest.

The calculator can use the Mifflin-St Jeor equation, a widely used equation for estimating resting energy expenditure.

Step 2: Estimate TDEE

Your estimated BMR is multiplied by an activity factor to estimate your Total Daily Energy Expenditure (TDEE).

TDEE represents the estimated number of calories your body uses each day based on resting energy requirements and typical activity.

Step 3: Apply the Deficit

The selected calorie deficit is subtracted from estimated maintenance calories:

Daily Calorie Target = TDEE − Calorie Deficit

For example:

TDEE = 2,400 calories

Deficit = 500 calories

Target = 1,900 calories/day

Mifflin-St Jeor Formula

For males:

BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5

For females:

BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161

The equation uses:

• Weight in kilograms
• Height in centimeters
• Age in years

These equations are widely used for estimating resting metabolic rate.

How to Calculate a Calorie Deficit

The basic calculation is:

Calorie Deficit = Maintenance Calories − Daily Calorie Intake

If your estimated maintenance level is 2,200 calories and you eat 1,800 calories, the estimated deficit is:

2,200 − 1,800 = 400 calories/day

Over seven days:

400 × 7 = 2,800 calories/week

This is an energy-balance estimate, not a guarantee of a specific amount of fat loss.

Calorie Deficit Examples

These are mathematical examples rather than individualized recommendations.

How Much of a Calorie Deficit Should You Use?

There is no single deficit that is appropriate for every person.

Clinical weight-management literature commonly discusses deficits in the range of 500–750 calories per day for weight-loss interventions, but the appropriate target depends on the individual and their circumstances.

A larger deficit is not automatically better.

Factors that can affect an appropriate calorie target include:

• Current body weight
• Body composition
• Age
• Activity level
• Medical conditions
• Medications
• Nutritional needs
• Previous weight changes
• Ability to maintain the eating pattern

For individualized guidance, a qualified healthcare professional or registered dietitian can help determine an appropriate approach.

What Is a 500-Calorie Deficit?

A 500-calorie daily deficit means your estimated daily energy expenditure is approximately 500 calories greater than your calorie intake.

For example:

Maintenance: 2,500 calories

Daily intake: 2,000 calories

Deficit: 500 calories

Across seven days:

500 × 7 = 3,500 calories

Older weight-loss guidance often uses 3,500 calories as a rough equivalent of one pound of body fat. However, real-world weight loss does not follow this relationship perfectly because energy expenditure changes as body weight changes and the body adapts over time.

Calorie Deficit and Weight Loss

Weight loss occurs when energy expenditure exceeds energy intake over time, but the actual rate of weight change can vary.

As body weight decreases, energy requirements can also decrease. This means the same calorie intake may produce a smaller deficit later in a weight-loss process.

Other factors can also affect changes on the scale, including:

• Water retention
• Glycogen levels
• Digestive contents
• Physical activity
• Changes in body composition
• Metabolic adaptation

For this reason, the calculator should be used as a planning estimate, not a promise of exactly how much weight you will lose.

Does Exercise Increase a Calorie Deficit?

Physical activity can increase energy expenditure.

For example, if your estimated maintenance expenditure increases because of greater activity while your food intake remains unchanged, the resulting energy deficit may increase.

However, exercise calories are difficult to estimate precisely, and wearable devices and exercise machines may not perfectly measure energy expenditure.

It is generally better to use consistent activity assumptions rather than repeatedly adding uncertain exercise calories to your daily target.

Why Your Actual Results May Differ

A calculator cannot perfectly measure your individual energy expenditure.

Your actual calorie needs may differ because of:

• Individual metabolism
• Muscle mass
• Daily movement
• Exercise
• Sleep
• Food intake accuracy
• Changes in body weight
• Metabolic adaptation
• Health conditions
• Medications

Estimated BMR and TDEE should therefore be treated as starting points rather than exact measurements.

Important Safety Considerations

This calculator is intended for general educational and planning purposes.

It should not replace individualized medical or nutritional advice.

Extra caution is appropriate for:

• People under 18
• Pregnant people
• Breastfeeding people
• People with eating disorders or a history of disordered eating
• People with certain medical conditions
• People taking medications that affect weight or metabolism

NIDDK’s Body Weight Planner, for example, is designed for adults and specifically excludes younger people and people who are pregnant or breastfeeding.

If you have a medical condition, are pregnant or breastfeeding, or are unsure whether calorie restriction is appropriate for you, speak with a qualified healthcare professional.

Frequently Asked Questions

What is a calorie deficit?

A calorie deficit occurs when you consume fewer calories than your body uses over a period of time.

How do I calculate my calorie deficit?

Subtract your daily calorie intake from your estimated maintenance calories:

Calorie Deficit = TDEE − Calorie Intake

What is TDEE?

TDEE stands for Total Daily Energy Expenditure. It is an estimate of the total calories your body uses each day, including energy used at rest and through activity.

What is BMR?

BMR stands for Basal Metabolic Rate. It estimates the energy your body requires to support basic physiological functions at rest.

What is the formula for a calorie deficit?

The basic formula is:

Calorie Deficit = Maintenance Calories − Calories Consumed

What is a 500-calorie deficit?

A 500-calorie deficit means your estimated daily energy expenditure is 500 calories greater than your daily calorie intake.

How many calories should I eat to lose weight?

That depends on your estimated energy needs, body size, activity, health status, and goals. A calculator can provide an estimate, but it cannot determine an individualized medical nutrition prescription.

Does a calorie deficit always cause weight loss?

A sustained energy deficit generally supports weight loss, but actual weight changes vary between individuals and over time.

Can I use this calculator every day?

You can use the calculator as a planning reference, but your estimated calorie needs may change as your weight, activity, or other circumstances change.

Is a calorie deficit safe for everyone?

No. Calorie restriction is not appropriate for everyone. Certain groups, including children, pregnant or breastfeeding people, and people with some medical or eating-related conditions, may require specialized guidance.

Is 1,200 calories a safe target?

A universal minimum should not be presented as appropriate for everyone. Calorie needs vary substantially by individual, and an appropriate target should account for age, body size, activity, health status, and nutritional requirements.