BMR Calculator
BMR Calculator
Estimate your Basal Metabolic Rate (BMR)—the number of calories your body burns at rest—using the Mifflin-St Jeor Equation.
Worked Examples
A 30-year-old male weighing 180 lbs at 5'10" has a BMR of approximately 1,822 kcal. If he works a sedentary desk job, his maintenance needs are 2,186 kcal.
However, if he trains for a triathlon (very intense exercise), his body requires 3,462 kcal daily—over 1,200 additional calories simply to maintain his weight while supporting his activity level.
A 45-year-old female weighing 200 lbs at 5'4" has a BMR of 1,617 kcal. After losing 40 lbs (down to 160 lbs), her BMR drops to 1,435 kcal.
This reveals why weight loss plateaus occur; as the body becomes smaller, it requires fewer calories to function at rest, meaning she must adjust her maintenance intake downward by 182 kcal to sustain her new weight.
Master Your Metabolism with MyApexCalc
Whether you are aiming to lose weight, build lean muscle, or simply maintain your current physique, understanding your body’s daily energy requirements is the ultimate starting point. Every day, your body burns a significant number of calories simply keeping your organs functioning, circulating blood, and maintaining body temperature—even if you stay in bed all day. Our free online bmr calculator removes the guesswork by establishing your baseline energy needs in seconds.
The Science of Metabolism: How Your BMR is Calculated
Your Basal Metabolic Rate (BMR) represents the absolute minimum number of calories your body needs to survive at rest. Our basal metabolic rate calculator utilizes the most accurate, medically recognized formulas to determine this baseline.
Our metabolic rate calculator supports both the Mifflin-St Jeor Equation (widely considered the most accurate for modern lifestyles) and the classic Harris-Benedict Equation.
The Mifflin-St Jeor Equation
For Men:
BMR = (10 × W) + (6.25 × H) - (5 × A) + 5
For Women:
BMR = (10 × W) + (6.25 × H) - (5 × A) - 161
* W = weight in kilograms, H = height in centimeters, A = age in years.
Once this baseline is established, you can multiply your BMR by an activity factor to determine your Total Daily Energy Expenditure (TDEE). This tells you exactly how many calories you need to consume to hit your target fitness goals.
Why Use the MyApexCalc Calculator for Metabolic Rate?
Instead of guessing your calorie needs or relying on complex manual formulas, MyApexCalc provides a seamless, secure, and instant health dashboard:
Dual Formula Support
Toggle between the modern Mifflin-St Jeor and revised Harris-Benedict formulas to compare baseline estimates across different clinical standards.
Metric and Imperial Inputs
Easily enter your stats in pounds and feet/inches or kilograms and centimeters without needing external conversion tools.
Instant TDEE Projections
View a clear breakdown showing how your baseline calorie burn scales up based on your daily physical activity levels.