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Calculating RMR - What's your Resting Metabolic Rate?

Our accurate RMR Calculator will work out your Resting Metabolic Rate. That's how many calories your body needs to stay alive. RMR covers all the basic bodily functions including keeping your heart beating, your lungs breathing, your brain functioning, and all the other tasks your body does to maintain life. Free accurate resting metabolic rate calculator.

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Accurate RMR Calculator

Our RMR Calculator is designed to help you work out how many calories your body burns to maintain life, which includes all the basic bodily functions. It does not account for sleeping, moving, eating, exercising, and other activties you do. It's just the most basic level of life.

Atlas Says: RMR is a great calculation when working out a minimum number of calories your body needs which is ideal for your fitness and nutrition plan. Never eat fewer calories than your RMR.

RMR vs TDEE?

Your RMR (Resting Metabolic Rate) and TDEE (Total Daily Energy Expenditure), differ slightly in that your TDEE calculation is your RMR plus all of your daily activities including sleeping, walking, working, exercising, eating, etc.

Atlas Says: Try our TDEE Calculator to discover how many calories you burn in a day.

What formulas do you use to work out RMR?

There are two formula's we use in this Resting Metabolic Calculator, they are: Mifflin-St Jeor and Katch-McArdle. If you include body fat percentage then the calculator uses the accurate Katch-McArdle formula. However, if you do not add your body fat percentage, then the calculator falls back to using the Mifflin-St Jeor formula (which is still very accurate). This formula excludes the activity level factor usually included in the above formulas to provide an accurate RMR calculation.

Mifflin-St Jeor Formula

Male = ( 10 x Weight in KGs ) + ( 6.25 x Height in CMs ) - ( 5 x Age ) + 5
Female = ( 10 x Weight in KGs ) + ( 6.25 x Height in CMs ) - ( 5 x Age ) - 161

Katch-McArdle Formula

Male & Female = 370 + ( 21.6 x ( Weight in KGs - (Body Fat % x Weight in KGs) ) )

Atlas Says: These formulas give an estimation of the number of calories your body burns staying alive. It's best to say that there is a margin of error of 10%, so regularly check and tweak to provide better results.

RMR Calculations and why calculating RMR is important

The single most important reason for calculating RMR is to do with accurately estimating how many calories your body requires depending on your own personal body composition - with the exclusion of your daily active levels.

Once you have this number, then you can use it as the backbone for your training and nutrition goals when you factor in your daily activity levels.

Calculating RMR for fat loss. If you are trying to reduce the amount of body fat then you will require a deficit against your RMR calculation. For the example of calculating RMR for fat loss, if your RMR is 2000 calories + daily activity level calories of 500, then a 10% calorie deficit will mean that you need to roughly eat 2250 calories a day to ensure you are in caloric deficit. The 10% deficit used here is a manageable deficit, a deficit of between 10% to 20% is recommended for reducing body fat - too many calories will also mean muscle loss.

Calculating RMR for muscle gain. Conversly if you are trying to gain muscle then you will require a calorie surplus against your RMR calculation. For the example of calculating RMR for muscle gain, if your RMR is 2000 calories + daily activity level calories of 500, then a 10% calorie surplus will mean that you need to roughly eat 2750 calories a day to ensure you are in caloric surplus. The 10% surplus used here is a manageable surplus, a surplus of between 10% to 20% is recommended for muscle gain - too many calories will also mean fat gain.

Please also note that these RMR calcualtion examples are when combining nutrition with resistance and cardio training for maximum benefit + don't forget your RMR does not include the calories you burn through your daily activity.

Atlas Says: RMR calulations are the backbone for fat loss, muscle gain, and weight maintenance. What is measured, can be improved.