Calorie Deficit Calculator

← Back to Health & Fitness

Calorie Deficit Calculator

Estimate daily maintenance calories, compare gentle calorie deficits, and see an illustrative daily intake target.

Free • Easy to Use • Adults 18+
Important: These are rough estimates, not a personal diet prescription. This tool is for adults, not for people who are pregnant, breastfeeding, or managing an eating disorder. Seek individualized guidance when needed.

How would you like to calculate?

Measurement Units
The Mifflin–St Jeor equation has two sex-specific variants; neither suits every person’s physiology.
Feet and remaining inches
Activity multipliers are broad estimates; actual energy needs can be quite different.

These percentages illustrate possible starting points, not a guarantee of weight loss or a medical recommendation.

📘 How This Calculator Works

Use My Details: The calculator estimates resting energy expenditure with the Mifflin–St Jeor formula, then multiplies it by an approximate activity factor to estimate daily maintenance calories (TDEE).

I Know My Maintenance: Enter your existing maintenance estimate and compare a 0%, 10%, 15%, or 20% reduction.

Estimated Daily Intake = Estimated Maintenance Calories × (1 − Selected Deficit Percentage ÷ 100)

Safety: This tool avoids displaying a reduced-calorie target when it falls below a conservative screening threshold or when the provided height and weight suggest an underweight BMI. These checks cannot replace individualized medical advice.

References: NIH/NIDDK Body Weight Planner, CDC Weight Management, and Mifflin–St Jeor equation.

🔗 Share This Calculator

Share the calculator or a link that restores your selected inputs and calorie estimate.

Privacy: Share Result links include your entered calorie information and, when applicable, age, height, weight, and activity level. Only send these links to people you trust.

📌

Save & Follow MyCruncher

Like this calculator? Save it for later and follow MyCruncher for more free calculators.

📌 Save This Calculator on Pinterest
Follow MyCruncher on Pinterest

About the Creator

MyCruncher — Founded by Bobby Dues

MyCruncher provides free online calculators designed to make everyday calculations easier to understand and use.

Meet Bobby Dues →

🔥 Calorie Deficit Calculator — Daily Calorie Guide

Wondering how to calculate a calorie deficit or estimate how many calories your body uses each day?

The free MyCruncher Calorie Deficit Calculator helps adults estimate daily maintenance calories, compare different calorie deficit percentages, and understand how daily calorie estimates work.

Enter your age, height, weight, activity level, and equation variant to estimate maintenance calories. You can also enter an existing maintenance-calorie estimate if you already know it.

The calculator compares maintenance with optional 10%, 15%, and 20% reductions. These are mathematical examples, not personal diet recommendations or guaranteed weight-loss rates.

Important: This calculator is for general educational use by adults aged 18 and older. It is not intended for children, adolescents, people who are pregnant or breastfeeding, or anyone managing an eating disorder. A qualified healthcare professional can help determine whether a calorie deficit is appropriate for your circumstances.

⚖️ What Is a Calorie Deficit?

A calorie deficit occurs when energy intake is lower than the energy your body uses over a period of time.

Calories provide energy for breathing, circulation, digestion, movement, and everyday physical activity.

The amount your body uses throughout a typical day is often called Total Daily Energy Expenditure, or TDEE.

Calorie Deficit Formula

Daily Calorie Deficit = Estimated Maintenance Calories − Daily Calorie Intake

For example, a person with an estimated maintenance level of 2,300 calories who consumes 2,000 calories would have an illustrative deficit of 300 calories for that day.

Example Difference: 2,300 − 2,000 = 300 calories per day

Actual energy expenditure may differ from the estimate. A calculated deficit does not guarantee a specific amount of weight loss.

📋 How to Use the Calorie Deficit Calculator

The calculator offers two ways to explore daily calorie estimates.

Option 1 — Use My Details

  1. Enter your age. This calculator is designed for adults aged 18 or older.
  2. Select an equation variant. Choose the male-based or female-based Mifflin–St Jeor formula variant.
  3. Choose your units. Enter your height and weight using pounds and feet/inches, or kilograms and centimeters.
  4. Select your activity level. Choose the option that best approximates your usual activity.
  5. Choose a calorie goal. Compare maintenance with a 10%, 15%, or 20% reduction.
  6. Calculate. Review the estimated maintenance, selected calorie difference, and illustrative daily target when the safety screening permits.

Option 2 — I Know My Maintenance

If you already have a daily maintenance-calorie estimate, select I Know My Maintenance.

Enter your estimate and choose a calorie goal. The calculator then compares your existing maintenance figure with the selected percentage.

This second mode does not recalculate your maintenance needs from your body measurements.

🔥 What Are Maintenance Calories and TDEE?

Maintenance calories are an estimate of the daily energy intake that may help keep body weight approximately stable over time.

TDEE stands for Total Daily Energy Expenditure. It reflects the energy your body uses throughout the day, including resting functions and activity.

Resting Energy vs. Total Daily Energy

Resting energy expenditure estimates calories used while the body is at rest.

Total daily energy expenditure also accounts for activity and other daily energy needs.

Estimated Maintenance Calories (TDEE) ≈ Estimated Resting Energy × Activity Multiplier

The activity multipliers are approximate planning factors. They are not exact measurements of individual metabolism.

Activity Levels Used by MyCruncher

Activity Level Multiplier
Mostly sitting 1.20
Lightly active 1.375
Moderately active 1.55
Very active 1.725
Extremely active 1.90
Activity note: Two adults with similar height, weight, and age can have different energy requirements. Activity, body composition, physiology, and other individual factors influence actual calorie needs.

📐 How Does the Mifflin–St Jeor Equation Work?

The MyCruncher Calorie Deficit Calculator uses the Mifflin–St Jeor equation to estimate resting energy expenditure.

The equation uses body weight in kilograms, height in centimeters, age in years, and one of two sex-specific formula variants.

Male-Based Equation

Resting Calories = (10 × Weight in kg) + (6.25 × Height in cm) − (5 × Age) + 5

Female-Based Equation

Resting Calories = (10 × Weight in kg) + (6.25 × Height in cm) − (5 × Age) − 161

These formulas estimate resting energy expenditure, often called RMR or REE. Strict basal metabolic rate, or BMR, is measured under more controlled conditions.

A formula variant is a mathematical assumption, not a complete representation of any individual's metabolism.

Formula limitation: Neither variant perfectly predicts the needs of every person. If the two options do not adequately represent your physiology, individualized guidance may be more appropriate.

🧮 Calorie Deficit Calculation Example

The following example matches the default settings in MyCruncher's calculator.

Example: Estimate Maintenance and a 15% Difference

  • Age: 35 years
  • Weight: 175 pounds
  • Height: 5 feet 8 inches
  • Equation: Female-based variant
  • Activity: Lightly active
  • Selected deficit: 15%

Step 1 — Convert the Measurements

175 pounds is approximately 79.38 kilograms.

5 feet 8 inches equals 172.72 centimeters.

Step 2 — Estimate Resting Energy

Apply the female-based Mifflin–St Jeor equation:

(10 × 79.38) + (6.25 × 172.72) − (5 × 35) − 161

Estimated Resting Energy: Approximately 1,537 calories/day

Step 3 — Estimate Maintenance

Multiply by the lightly active factor of 1.375.

1,537.29 × 1.375 ≈ 2,114.

Estimated Maintenance: Approximately 2,114 calories/day

Step 4 — Compare a 15% Reduction

2,114 × 0.15 ≈ 317 calories.

2,114 − 317 ≈ 1,797 calories.

Illustrative Daily Intake: Approximately 1,797 calories/day

This is an example of the calculator's mathematical output, not a recommended intake for everyone with similar measurements.

📊 Compare 10%, 15%, and 20% Calorie Deficits

MyCruncher lets visitors compare several different percentage changes from estimated maintenance calories.

The following comparison uses an illustrative maintenance estimate of 2,300 calories per day.

Selected Option Daily Difference Illustrative Daily Intake
Maintain — 0% 0 calories 2,300 calories
10% reduction 230 calories 2,070 calories
15% reduction 345 calories 1,955 calories
20% reduction 460 calories 1,840 calories

How to Calculate a Percentage-Based Target

Illustrative Daily Intake = Maintenance Calories × (1 − Deficit Percentage ÷ 100)

Example: Known Maintenance of 2,300 Calories

Suppose an adult already has a maintenance estimate of 2,300 calories per day.

They select the 15% comparison option.

2,300 × 0.15 = 345

2,300 − 345 = 1,955

Illustrative Daily Target: 1,955 calories/day

This is the same result shown by the calculator's I Know My Maintenance path for these inputs.

The percentages are comparison options, not clinical guidelines or a recommendation to choose the largest reduction.

🎯 How Accurate Is a Calorie Deficit Calculator?

A calorie deficit calculator provides an estimate based on mathematical assumptions. It cannot measure a person's exact daily calorie expenditure.

Several factors may influence actual energy requirements:

  • Body composition: People with different proportions of muscle and other tissues may use energy differently.
  • Physical activity: Exercise, work, walking, and daily movement affect energy expenditure.
  • Age and physiology: Energy requirements differ between individuals and may change over time.
  • Medical circumstances: Certain conditions and medications can affect energy needs or appropriate nutrition planning.
  • Changes over time: Maintenance calorie needs may change as body weight, activity, or other factors change.
Remember: A calculated daily deficit cannot reliably predict a specific number of pounds lost per week. Real-world weight changes are more complex than a fixed calorie-to-pound conversion.

💚 Safe and Sustainable Calorie Planning

Adequate energy and nutrition are important for overall health. A lower calorie number is not automatically a better or safer target.

Before making a significant change to calorie intake, consider your individual nutrition needs, activity, and medical circumstances.

Why Does MyCruncher Sometimes Hide a Target?

The calculator includes basic screening safeguards for unusually low calculated intakes and certain underweight BMI estimates.

When these checks are triggered, the calculator may display Not shown instead of a reduced-calorie target.

These safeguards are limited screening rules, not a medical assessment or a guarantee that any other result is safe.

Who Should Seek Individualized Guidance?

Children and teenagers, people who are pregnant or breastfeeding, and people with an eating disorder or a history of disordered eating should not use this calculator to set calorie restriction targets.

People with medical conditions, special nutritional needs, or questions about their weight or medications should seek advice from an appropriate healthcare professional.

Balanced Health Habits Matter

Healthy weight management, when appropriate, considers more than a calorie number. Nutrition quality, regular physical activity, adequate sleep, and stress management all contribute to overall well-being.

❓ Calorie Deficit Calculator FAQs

What is a calorie deficit?

A calorie deficit occurs when energy intake is lower than energy expenditure over a period of time. The calculation is an estimate, not a guaranteed prediction of weight change.

How do I calculate a calorie deficit?

Subtract daily calorie intake from estimated maintenance calories. The difference is the estimated calorie deficit for that day.

What are maintenance calories?

Maintenance calories are an estimate of the energy intake associated with approximately stable body weight over time.

What does TDEE mean?

TDEE stands for Total Daily Energy Expenditure. It estimates daily energy use, including resting functions and activity.

What is the difference between BMR and TDEE?

BMR describes energy use under specific resting conditions. TDEE reflects total daily energy expenditure, which also includes movement and activity.

What is the Mifflin–St Jeor equation?

It is a published equation used to estimate resting energy expenditure from height, weight, age, and a selected sex-specific formula variant.

Does activity level affect the result?

Yes. The calculator multiplies estimated resting energy by an approximate activity factor. A higher selected factor usually increases estimated maintenance calories.

Can I use pounds and inches?

Yes. Choose US units for pounds, feet, and inches. You can also select metric units for kilograms and centimeters.

What if I already know my maintenance calories?

Select I Know My Maintenance, enter your existing estimate, and compare maintenance with the available percentage options.

What does a 15% calorie deficit mean?

It is a mathematical reduction of 15% from an estimated maintenance amount. For example, 15% of 2,300 calories is 345 calories, leaving an illustrative intake of 1,955.

Is a 20% calorie deficit right for everyone?

No. A percentage reduction does not determine whether the resulting intake meets an individual's nutritional or medical needs.

Why does the calculator say Not shown?

The calculator may withhold a reduced-calorie target when its basic safety checks flag an unusually low intake or certain underweight BMI estimates.

Can I calculate maintenance without a calorie deficit?

Yes. Choose Maintain My Weight — No Deficit to view estimated maintenance calories without applying a reduction.

Does a calorie deficit guarantee weight loss?

No specific weight-loss rate is guaranteed. Actual results depend on individual energy expenditure, nutrition, physiological changes, and other factors.

How often do maintenance calorie needs change?

Needs may change as activity, body weight, and other factors change. A previous estimate may no longer describe current energy requirements.

Can teenagers use this calculator?

No. This calculator is intended for adults aged 18 and older. Children and adolescents have different nutrition and growth requirements.

Can I share my calorie calculation?

Yes. Share Result can create a link that restores your entered calculator details and result. Be aware that the shared link may contain sensitive personal measurements.

Is MyCruncher's Calorie Deficit Calculator free?

Yes. The Calorie Deficit Calculator is free to use online.

🧮 More Free MyCruncher Health & Fitness Calculators

MyCruncher offers additional free calculators for exploring daily energy needs, body measurements, hydration, and sleep planning.

🔥 Calorie Calculator

Estimate daily calorie needs using body measurements, activity level, and the calculator's existing energy formulas.

⚖️ BMI Calculator

Estimate body mass index using height and weight. BMI is a general screening measure and is not a diagnosis of health or body composition.

💧 Water Intake Calculator

Explore an illustrative daily hydration estimate based on body weight, activity, and other inputs.

🌙 Sleep Calculator

Plan possible bedtime and wake-up times using the calculator's sleep-cycle assumptions.

🔥 Calorie Calculator → ⚖️ BMI Calculator → 💧 Water Intake Calculator → 🌙 Sleep Calculator →

📚 Scientific References and Health Information

The calculator uses an established resting-energy equation and illustrative activity and percentage assumptions.

The following resources provide additional information about energy needs and weight management:

🚀 Explore More Free MyCruncher Calculators

Find free calculators for health and fitness, everyday math, cooking, finance, home projects, and more.

💙 Health & Fitness Calculators → 🧮 Browse All Calculators →

📌 Important Calorie Calculator Information

The MyCruncher Calorie Deficit Calculator provides mathematical estimates based on entered information and general activity assumptions.

It does not measure actual metabolic rate, diagnose a health condition, prescribe an appropriate diet, or guarantee weight-loss outcomes.

An illustrative intake value is not necessarily a safe or nutritionally adequate target for any particular person.

For individualized nutrition or weight-management advice, consult a qualified healthcare professional who understands your needs.

← Back to Health & Fitness