Introduction
Your resting metabolic rate (RMR) is the number of calories your body burns each day just to stay alive. Even when you sleep, your body uses energy to breathe, pump blood, and keep your organs working. Knowing your RMR helps you understand how many calories you need to eat each day to maintain, lose, or gain weight.
This free RMR calculator uses three trusted formulas—Mifflin-St Jeor, Harris-Benedict Revised, and Cunningham—to estimate your resting metabolic rate based on your age, sex, height, weight, and activity level. It also shows your total daily energy expenditure (TEE), which is the full number of calories you burn when daily movement and exercise are included. Enter your details below to get your results in seconds, complete with a step-by-step breakdown of how each formula works.
How to Use Our RMR Calculator
Enter your body stats below to find your resting metabolic rate (RMR). The calculator will show how many calories your body burns at rest each day and estimate your total daily calorie needs.
Unit System: Pick Imperial or Metric. This sets your height and weight fields to pounds and feet or kilograms and centimeters. You can also change units for each field on its own.
Age: Enter your age in years. You must be between 18 and 100 years old to use this calculator.
Biological Sex: Choose Male or Female. The formulas use different numbers for each sex.
Height: Enter your height in feet and inches or in centimeters. Use the toggle above the field to switch between the two.
Weight: Enter your weight in pounds or kilograms. Use the toggle above the field to switch between the two.
Activity Level: Select how active you are on a typical week. Options range from Sedentary (little or no exercise) to Very Heavy (multiple daily training sessions). This is used to estimate your total daily calories burned.
Body Composition Input: Choose how you want to handle body fat. Pick "Use standard formulas" if you do not know your body fat percentage. Pick "I know my body fat percentage" and type it in to unlock the Cunningham formula, which can give a more accurate result. If you do not know your exact number, you can use our Body Fat Calculator to find it. Pick "Estimate body fat % from BMI" to let the calculator guess it for you based on your BMI. If you are African American, check the adjustment box for a more precise estimate.
Calculate RMR: Press the blue Calculate button to see your results. You will get your RMR from up to three proven formulas, a bar chart comparison, a step-by-step math breakdown, a calorie table for every activity level, and a comparison to population averages.
What Is Resting Metabolic Rate (RMR)?
Your resting metabolic rate is the number of calories your body burns each day just to stay alive. Even when you are sleeping or sitting still, your body uses energy to breathe, pump blood, and keep your organs working. RMR makes up about 60% to 75% of all the calories you burn in a day. To see a complete picture of your daily calorie burn including exercise and activity, try our Calories Burned Calculator.
How This RMR Calculator Works
This calculator uses your age, sex, height, and weight to estimate your RMR. It gives you results from up to three trusted formulas:
- Mifflin-St Jeor (1990) — The most recommended formula for most adults. It uses your total body weight, height, age, and sex.
- Harris-Benedict Revised (1984) — An older formula that is still widely used. It works the same way as Mifflin-St Jeor but uses different numbers in the equation.
- Cunningham / Katch-McArdle (1991) — This formula uses your lean body mass instead of total weight. It only appears when you enter your body fat percentage. It can be more accurate for people who are very muscular or have a known body fat level. Athletes and strength trainers may also find our FFMI Calculator helpful for understanding their body composition.
RMR vs. BMR
RMR and basal metabolic rate (BMR) are very similar. BMR is measured under strict lab conditions after a full night of sleep and fasting. RMR is measured under slightly less strict conditions, so it tends to be a tiny bit higher. In everyday use, the two terms mean nearly the same thing. If you want to compare your results, you can also check our BMR Calculator for an alternative estimate.
Total Daily Energy Expenditure (TEE)
Your RMR only covers the calories you burn at rest. To find out how many total calories you burn each day, the calculator multiplies your RMR by an activity factor. A more active lifestyle means a higher multiplier and more calories burned. This total number is called your Total Energy Expenditure, or TEE. For a more detailed breakdown of your daily energy needs, you can also use our TDEE Calculator. Knowing your TEE helps you plan how much to eat whether your goal is to lose weight, gain muscle, or maintain your current weight.
Why RMR Matters
Knowing your RMR gives you a starting point for building a nutrition plan. If you eat fewer calories than your TEE, you will likely lose weight over time—our Calorie Deficit Calculator can help you set a safe daily target. If you eat more, you will likely gain weight. Once you know your calorie target, use our Macro Calculator to find the right balance of protein, carbs, and fat, or our Protein Calculator to dial in your daily protein needs. Your RMR can also change based on factors like age, muscle mass, and hormones. Regular exercise and strength training can help raise your RMR by building more lean muscle. To track your overall daily calorie needs as your fitness level changes, our Calorie Calculator is another useful tool to keep on hand.