Use this BMR Calculator to estimate your Basal Metabolic Rate—the number of calories your body burns at complete rest. Knowing your BMR helps you set realistic calorie targets for weight loss, maintenance, or muscle gain.
What is BMR?
Basal Metabolic Rate (BMR) is the energy your body requires to keep vital functions running while at rest—breathing, circulation, cell production, and temperature regulation. It does not include calories burned during movement, exercise, or daily tasks. Because BMR is the foundation of your total daily energy expenditure (TDEE), understanding it is the first step in building a smart nutrition plan.
How this BMR Calculator works
This calculator uses the widely accepted Mifflin–St Jeor equation, which research shows provides reliable estimates for most adults. Simply enter your sex, age, height, and weight. You can use either metric (kg, cm) or imperial (lb, ft/in) units. The calculator converts everything to the correct units behind the scenes and returns your estimated BMR in calories per day.
Why Mifflin–St Jeor?
The Mifflin–St Jeor formula is considered more accurate than older equations for modern populations. It adjusts for age, height, weight, and sex to estimate resting energy needs. While no equation is perfect for every individual, it is a strong starting point for most nutrition and fitness goals.
How to use the BMR Calculator
- Select your sex (male or female).
- Enter your age in years. Adult ranges are best suited for these equations.
- Provide your weight and choose kg or lb.
- Enter your height in centimeters or in feet and inches.
- Click “Calculate BMR” to see your daily resting calorie estimate.
For the most accurate results, use a recent, consistent morning weight and a measured height (not an estimate). If you are between sizes in height or unsure, rounding to the nearest whole number is fine.
From BMR to daily calorie targets
BMR is your baseline. To estimate your daily calorie needs, multiply your BMR by an activity factor to get Total Daily Energy Expenditure (TDEE). For example, if you are lightly active (1–3 exercise sessions per week), your TDEE might be around BMR × 1.375. Moderately active individuals often use 1.55, and very active individuals use 1.725 or higher. This gives you a more practical daily target.
Setting goals using your BMR
- Weight loss: Aim for a calorie intake slightly below your TDEE (for example, 300–500 calories per day less).
- Maintenance: Target your TDEE to keep your weight stable.
- Muscle gain: A modest calorie surplus over TDEE, paired with resistance training and adequate protein, supports growth.
Remember, BMR is an estimate. Individual variability—such as body composition, genetics, hormonal status, sleep, and stress—can influence your true energy needs.
Tips to improve accuracy
- Use consistent units and double-check entries before calculating.
- Measure height without shoes and stand straight against a wall.
- Weigh yourself at a consistent time of day, ideally in the morning.
- Recalculate after significant changes in weight or training volume.
Common questions about BMR
Is BMR the same as RMR?
They are similar. Resting Metabolic Rate (RMR) is typically measured under less strict conditions than BMR, so RMR results are often slightly higher. Many calculators and articles use the terms interchangeably for practical purposes.
Do I need to fast or rest before calculating BMR?
No. This calculator uses a predictive equation, not a metabolic test. Just enter your details and you will get an estimate. Clinical metabolic testing under controlled conditions would be needed for a direct measurement.
Can I use imperial units?
Yes. Select pounds for weight and feet/inches for height. The calculator converts them to metric units internally to run the formula.
Takeaway
Your BMR is the foundation for setting calorie goals. Use the result as a starting point, then adjust based on real-world feedback such as changes in body weight, strength progression, performance, and how you feel day to day. Periodic recalculations help keep your plan aligned with your current body and activity level.