Mifflin-St Jeor Calculator — Calculate Your BMR & Daily Calories Free
Use the most accurate calorie calculator trusted by nutritionists. Enter your age, weight, height, and activity level to get your personalized BMR and TDEE instantly.
Calculate NowCalculate Your Calories
BMR
1680
calories/day
TDEE
2604
calories/day
Fat Loss
2104
calories/day
-500 cal/day
Weight Gain
3104
calories/day
+500 cal/day
Maintenance: 2604 calories/day
These are estimates. Individual needs vary. Consult a healthcare professional for personalized advice.
What Your Results Mean
What Is BMR (Basal Metabolic Rate)?
Your basal metabolic rate (BMR) is the foundational baseline of your metabolism. It represents the exact number of daily calories your body requires just to stay alive if you were to stay in bed all day.
Even when you are completely at rest, your body is working hard behind the scenes — pumping blood, breathing, regulating body temperature, and repairing cells.
Think of your BMR as your body's "engine idling" cost.
Usage of BMR
Your Basal Metabolic Rate (BMR) represents the minimum amount of energy your body needs to stay alive and perform essential functions, even when you are completely at rest. These functions include breathing, circulating blood, regulating body temperature, supporting brain activity, and maintaining healthy organs.
Knowing your BMR provides a strong starting point for creating a realistic nutrition and fitness plan. Whether your goal is losing weight, building muscle, or maintaining your current weight, understanding how many calories your body burns naturally helps you make informed decisions about your daily calorie intake.
For example, an average adult male may consume around 2,500 calories per day, while his BMR may be approximately 1,700 calories. This means that nearly 70% of his daily calorie needs are used simply to keep his body functioning. The remaining calories are burned through everyday activities such as walking, working, exercising, household tasks, and other forms of movement.
If your goal is weight loss, your BMR helps determine how many calories your body already burns before exercise is considered. This makes it easier to calculate an appropriate calorie deficit without reducing your intake too aggressively.
If you're aiming for muscle gain or healthy weight gain, your BMR serves as the foundation for estimating how many additional calories you should consume to create a sustainable calorie surplus.
Keep in mind that BMR is not the same for everyone. Several factors influence your result, including:
- •Age
- •Biological sex
- •Height
- •Body weight
- •Lean muscle mass
- •Body composition
- •Certain health conditions and hormonal changes
Because these factors vary from person to person, your BMR should always be viewed as a personalized estimate rather than a fixed number.
Common BMR Formulas
Over the years, researchers have developed several equations to estimate Basal Metabolic Rate. While each formula uses a slightly different approach, they all aim to calculate the number of calories your body burns at complete rest.
Most modern calculators rely on one or more of the following scientifically recognized equations:
Mifflin–St Jeor Equation
Widely considered the most accurate choice for healthy adults and commonly recommended by nutrition professionals.
Harris–Benedict Equation
One of the earliest BMR formulas and still widely used for general calorie estimation.
Revised Harris–Benedict Equation
An updated version of the original formula that improves accuracy using modern research data.
Katch–McArdle Formula
Best suited for individuals who know their body fat percentage, as it calculates BMR based on lean body mass.
Most BMR equations require the same basic information:
- •Weight (kilograms)
- •Height (centimeters)
- •Age (years)
- •Sex (male or female)
Providing accurate measurements helps produce a more reliable BMR estimate, which can then be used to calculate your Total Daily Energy Expenditure (TDEE) and daily calorie targets.
What Is TDEE (Total Daily Energy Expenditure)?
While your BMR covers your survival energy, your total daily energy expenditure (TDEE) accounts for everything else you do. Your TDEE is the total amount of daily calorie needs based on your active lifestyle.
It is calculated by multiplying your baseline BMR by an activity level multiplier.
The Mifflin-St Jeor equation uses five distinct activity tiers to find your TDEE:
- 1Sedentary (BMR × 1.2): Little to no exercise; desk job lifestyle.
- 2Lightly Active (BMR × 1.375): Light exercise or sports 1 to 3 days per week.
- 3Moderately Active (BMR × 1.55): Moderate exercise or sports 3 to 5 days per week.
- 4Very Active (BMR × 1.725): Hard exercise or intense sports 6 to 7 days per week.
- 5Extra Active (BMR × 1.9): Very strenuous daily exercise, physical labor, or double training sessions.
How to Use the BMR Calculator
Calculating your Basal Metabolic Rate (BMR) takes less than a minute. Simply enter a few personal details, and the calculator will estimate the number of calories your body burns each day while at complete rest.
| Step | Instructions |
|---|---|
| 1 | Select your sex by choosing Male or Female. This allows the calculator to apply the correct BMR formula. |
| 2 | Enter your age in years using your current age. |
| 3 | Choose your preferred height unit (Centimeters or Feet & Inches), then enter your height. |
| 4 | Select your weight unit (Kilograms or Pounds) and enter your current body weight. |
| 5 | Pick the BMR equation you'd like to use. The Mifflin–St Jeor Equation is pre-selected because it is widely considered the most accurate option for most adults. |
| 6 | Review your information before calculating. The calculator automatically converts units, so you can use the measurement system you're most comfortable with. |
| 7 | Click the Calculate BMR button to generate your personalized results instantly. |
| 8 | Your results will display your estimated Basal Metabolic Rate (BMR) along with your daily calorie needs (TDEE) based on different activity levels, making it easier to plan for weight loss, weight maintenance, or muscle gain. |
Which Calorie Goal Is Right for You?
Once our BMR calculator reveals your TDEE, you can map out how many calories you should eat to hit your personal goals. Your target splits into three main paths:
Fat Loss
Calorie Deficit: To lose weight, consume 500 calories fewer than your TDEE. This forces your body to burn stored fat for fuel, resulting in healthy, sustainable weight loss.
Maintenance
Calorie Balance: Eating at your TDEE maintains your current weight. Perfect for those who have reached their goal and want to stay there.
Weight Gain
Calorie Surplus: To build muscle, add 300-500 calories above your TDEE. Combined with strength training, this supports muscle growth.
The Mifflin-St Jeor Equation
The Mifflin-St Jeor equation was developed in 1990 and is considered the most accurate formula for calculating BMR. It is widely used by nutritionists and healthcare professionals.
For Men:
BMR = (10 × weight) + (6.25 × height) - (5 × age) + 5
For Women:
BMR = (10 × weight) + (6.25 × height) - (5 × age) - 161
Note: Weight is in kilograms, height is in centimeters, and age is in years.
Frequently Asked Questions
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