Understanding TDEE and BMR

TDEE (Total Daily Energy Expenditure)

The total number of calories your body burns in a day, including all physical activity. It determines how many calories you need to maintain, lose, or gain weight.

BMR (Basal Metabolic Rate)

The number of calories your body needs at complete rest to maintain basic life functions such as breathing, circulation, and cell production. BMR typically accounts for 60-75% of your total daily calorie burn.

Key Insight: Your TDEE is always higher than your BMR because it includes calories burned through movement, exercise, and digestion throughout the day.

Three Scientifically Validated Formulas

This calculator uses multiple evidence-based formulas to provide accurate calorie estimates:

Mifflin-St Jeor

Considered the most accurate for most adults.

Uses weight, height, age, and gender
Recommended by nutrition experts
Best for general population

Harris-Benedict (Revised)

A well-established formula with proven reliability.

Uses same inputs with different coefficients
Extensively validated over decades
Reliable alternative method

Katch-McArdle

Precision formula for athletic individuals.

Uses lean body mass calculation
Requires body fat percentage
More accurate for athletes

Table of Contents

1. Understanding TDEE and BMR
2. How to Use the Calorie Calculator
3. Calculator Features
4. Frequently Asked Questions

How to Use the Calorie Calculator

Choose Your Unit System

Select Metric (kg/cm) or Imperial (lbs/ft) at the top of the calculator. The interface will automatically adjust all input fields to match your preferred measurement system.

Enter Your Personal Details

Input your weight, height, and age accurately. Select your gender from the available options. These values form the foundation of your calorie calculations.

Select Activity Level (For TDEE)

Choose your activity level from five options ranging from Sedentary to Extra Active. Your TDEE is calculated by multiplying your BMR by the activity multiplier corresponding to your lifestyle.

Calculate BMR (Optional)

Switch to the BMR tab to view your basal metabolic rate. Optionally enter your body fat percentage to enable the Katch-McArdle formula for a more personalized comparison.

View Your Results

Results update instantly as you type or change any input. No need to click a calculate button — the calculator responds in real-time to provide immediate feedback.

Understanding Your Results

TDEE Value

Your estimated total daily calorie expenditure based on your BMR and selected activity level. This is the number of calories you burn each day.

Goal Cards

Shows personalized calorie targets for losing weight (-500 cal/day), maintaining current weight, or gaining weight (+500 cal/day).

Macro Breakdown

Displays recommended daily protein (30%), carbohydrates (45%), and fat (25%) in grams for your selected goal, with visual progress bars.

Formula Comparison

In BMR mode, compare results from Mifflin-St Jeor, Harris-Benedict, and Katch-McArdle formulas side by side to see how different methods estimate your metabolism.

Calculator Features

TDEE Calculation with Activity Levels

Choose from five precisely defined activity levels, each with a specific multiplier applied to your BMR. This provides an accurate estimate of your daily calorie burn based on your lifestyle and exercise habits.

Activity Level	Description	Multiplier	Example
Sedentary	Little or no exercise	BMR × 1.2	Desk job, minimal movement
Lightly Active	Light exercise 1-3 days/week	BMR × 1.375	Walking, light sports occasionally
Moderately Active	Moderate exercise 3-5 days/week	BMR × 1.55	Regular gym sessions, active lifestyle
Very Active	Hard exercise 6-7 days/week	BMR × 1.725	Daily intense workouts, sports training
Extra Active	Very hard exercise + physical job	BMR × 1.9	Athlete training + manual labor

Multiple BMR Formulas

Compare your BMR across three established formulas to understand the range of your metabolic rate. The Mifflin-St Jeor equation serves as the primary result, while Harris-Benedict and Katch-McArdle results are displayed for comparison.

Formula Activation: The Katch-McArdle formula becomes available when you enter your body fat percentage, providing a more personalized calculation based on lean body mass.

Weight Goal Recommendations

Receive personalized calorie targets tailored to three distinct goals:

Calorie Deficit

Lose Weight

500 calorie daily deficit
~0.5 kg (1 lb) loss per week
Minimum 1,200 cal/day enforced
Safe, sustainable approach

Calorie Surplus

Gain Weight

500 calorie daily surplus
~0.5 kg (1 lb) gain per week
Supports muscle building
Controlled weight increase

Safety First: The calculator enforces a minimum of 1,200 calories per day for weight loss to prevent unhealthy restriction and ensure adequate nutrition.

Macro Breakdown

For each weight goal, the calculator provides a scientifically-backed macronutrient split designed to support your objectives:

Protein 30%

Carbohydrates 45%

Fat 25%

Grams are calculated based on your calorie target, with visual progress bars for easy comparison and tracking.

Dual Unit Support

Switch seamlessly between Metric (kilograms and centimeters) and Imperial (pounds, feet, and inches) with a single click. Results recalculate automatically when you change units, ensuring accuracy regardless of your preferred measurement system.

Metric System

International standard measurements

Weight in kilograms (kg)
Height in centimeters (cm)
Precise decimal inputs

Imperial System

US customary measurements

Weight in pounds (lbs)
Height in feet and inches
Familiar US format

Real-Time Calculation

Experience instant feedback with real-time calculations. All results update automatically as you type or change any input — no need to click a calculate button. This dynamic approach allows you to experiment with different values and immediately see how they affect your calorie needs.

Instant Results: The calculator processes your inputs in milliseconds, providing immediate visual feedback through updated numbers, progress bars, and goal cards.

Frequently Asked Questions

What is the difference between TDEE and BMR?

BMR (Basal Metabolic Rate) is the calories your body burns at complete rest — just to keep you alive. It covers essential functions like breathing, circulation, cell production, and nutrient processing.

TDEE (Total Daily Energy Expenditure) includes your BMR plus all calories burned through physical activity, digestion (thermic effect of food), and daily movement. TDEE is always higher than BMR because it accounts for everything you do throughout the day.

Example: If your BMR is 1,500 calories and you're moderately active, your TDEE might be around 2,325 calories (1,500 × 1.55).

Which formula is the most accurate?

The Mifflin-St Jeor equation is generally considered the most accurate for most adults and is recommended by the Academy of Nutrition and Dietetics. It was developed in 1990 and has been validated across diverse populations.

If you know your body fat percentage, the Katch-McArdle formula may be more accurate, especially for athletes or very lean individuals, because it uses lean body mass rather than total body weight.

The Mifflin-St Jeor equation is more predictive of measured resting metabolic rate than the Harris-Benedict equation in non-obese individuals.
— Academy of Nutrition and Dietetics

Differences of 50-200 calories between formulas are normal and reflect different mathematical approaches to estimating metabolism.

How do I choose the right activity level?

Be honest about your actual daily activity. Many people overestimate their activity level, which can lead to consuming more calories than needed.

Sedentary: Desk job with no exercise, minimal walking
Lightly Active: Light exercise or sports 1-3 days per week
Moderately Active: Moderate exercise or sports 3-5 days per week
Very Active: Hard exercise or sports 6-7 days per week
Extra Active: Very intense exercise plus a physically demanding job

Common Mistake: Don't count planned exercise if you're inconsistent. Choose the level that reflects your actual average weekly activity over the past month.

Is a 500 calorie deficit safe for weight loss?

A 500 calorie daily deficit typically results in about 0.5 kg (1 lb) of weight loss per week, which is generally considered safe and sustainable by health professionals.

Too Aggressive

1,000+ Calorie Deficit

Muscle loss
Nutrient deficiencies
Metabolic slowdown
Difficult to maintain

Recommended

500 Calorie Deficit

Preserves muscle mass
Adequate nutrition
Sustainable long-term
Steady progress

Safety Feature: The calculator enforces a minimum of 1,200 calories per day to prevent unhealthy restriction. Always consult a healthcare professional before starting a diet, especially if you have medical conditions.

Why do the three formulas give different results?

Each formula uses different mathematical coefficients and approaches based on the research populations they were developed from:

Mifflin-St Jeor and Harris-Benedict use weight, height, age, and gender but with different equations derived from different study populations
Katch-McArdle uses lean body mass instead, which accounts for muscle-to-fat ratio and may be more accurate for athletic individuals
Differences of 50-200 calories between formulas are normal and expected

Think of these formulas as providing a range rather than a single exact number. Your actual metabolic rate can vary based on genetics, hormones, stress, sleep, and other factors not captured by these equations.

Pro Tip: Use the average of the formulas as your starting point, then adjust based on real-world results over 2-4 weeks. Track your weight and energy levels to fine-tune your calorie intake.

Is my data stored or shared?

No. All calculations happen entirely in your browser using JavaScript. Your personal information is never sent to any server, stored in any database, or shared with any third parties.

Complete Privacy: This calculator operates 100% client-side. When you close your browser, all your data is gone. No cookies, no tracking, no data collection.

This approach ensures maximum privacy and security for your personal health information.

Formula	BMR (cal)
Mifflin-St Jeor	--
Harris-Benedict	--
Katch-McArdle *	--