BMR Calculator by Age, Weight & Height
A BMR calculator by age, weight, and height estimates how many calories the body burns each day simply staying alive β breathing, circulating blood, and keeping organs running, without any physical activity factored in.
BMR Calculator
Calculate your Basal Metabolic Rate using your age, weight, height, and sex.
This is the estimated number of calories your body needs at complete rest to support basic functions.
Estimated calories to maintain your current weight.
Approximate daily intake using a 500 kcal deficit.
Estimated Daily Calorie Needs
Basal Metabolic Rate (BMR) is an estimate of the calories your body uses each day to perform essential functions such as breathing, circulation, and maintaining body temperature while at rest.
Your actual calorie needs can be higher depending on your physical activity, exercise, and other individual factors.
What Is BMR?
Basal Metabolic Rate, or BMR, represents the minimum number of calories the body needs at complete rest to maintain essential functions. A BMR calculator for men and women uses age, weight, height, and biological sex to estimate this number, since metabolic rate naturally differs based on all four factors. Most BMR calculators, including a BMR calculator with age and height and weight, rely on validated scientific formulas rather than rough estimates, which is why the inputs matter so much for accuracy.
How BMR Is Calculated: The Mifflin-St Jeor Equation
The most widely trusted BMR formula in modern use is the Mifflin-St Jeor equation, published in 1990 and shown in multiple validation studies to outperform older formulas like Harris-Benedict, particularly across a wide range of body types. A BMR calculator based on age, weight, and height using this equation applies the following:For men: BMR = (10 Γ weight in kg) + (6.25 Γ height in cm) β (5 Γ age in years) + 5 For women: BMR = (10 Γ weight in kg) + (6.25 Γ height in cm) β (5 Γ age in years) β 161Whether using a BMR calculator metric or a BMR calculator imperial version, the underlying math stays the same β imperial inputs are simply converted to kilograms and centimeters behind the scenes before applying the formula.
Does Age Affect BMR?
Yes. Metabolic rate tends to decline gradually with age, largely due to a natural reduction in muscle mass over time, which is why the formula subtracts a value based on age.
Does Weight and Height Affect BMR?
Both do. A BMR calculator based on weight and a BMR calculator based on height both reflect real physiological patterns β more body mass and greater height generally require more resting energy to maintain.
Does Gender Affect BMR?
Biological sex affects BMR primarily due to differences in average muscle mass and body composition, which is why the Mifflin-St Jeor equation uses separate constants for men and women.
BMR vs. TDEE: What's the Difference?
BMR only accounts for calories burned at rest. Total Daily Energy Expenditure, or TDEE, builds on BMR by factoring in activity level β everything from daily movement to structured exercise. A BMR and calorie calculator typically multiplies BMR by an activity multiplier to estimate daily calorie needs for weight maintenance, weight loss, or weight gain, depending on the goal.
How to Increase BMR
Building lean muscle mass through resistance exercise is one of the most effective ways to raise resting metabolic rate over time, since muscle tissue burns more calories at rest than fat tissue. Staying adequately fed also matters, as prolonged calorie deficits can sometimes lower metabolic rate as the body adapts.
Frequently Asked Questions About BMR Calculators
What is BMR and why does it matter?
BMR is the number of calories the body burns at rest, and it forms the baseline for calculating daily calorie needs for weight loss, gain, or maintenance.
How accurate is a BMR calculator?
The Mifflin-St Jeor equation predicts measured BMR within about 10% for most healthy adults, though individual results can vary based on body composition.
What's the difference between BMR and TDEE?
BMR reflects calories burned at rest only, while TDEE adds physical activity on top of BMR to estimate total daily calorie needs.
How many calories does the body burn at rest?
This varies by individual but typically ranges from about 1,200 to 2,000 calories per day, depending on age, weight, height, and sex.
Can BMR be increased?
Yes, primarily through building muscle mass, since muscle tissue requires more resting energy than fat tissue.
Note: This Tool is for educational purposes only and does not diagnose or treat any medical condition.