Accurate RMR Calculator

Accurate RMR Calculator

Resting Metabolic Rate

This may be the most accurate RMR Calculator online. It's 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 activities you do. It's just the most basic level of life.

Try our Accurate TDEE Calculator to get your Total Daily Energy Expenditure.

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.

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 formulas we use in this Resting Metabolic Calculator: 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) ) )

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 activity 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 example, if your RMR is 2,000 calories + daily activity level calories of 500, then a 10% calorie deficit will mean that you need to roughly eat 2,250 calories a day to ensure you are in a caloric deficit. A deficit of between 10% to 20% is recommended for reducing body fat — too many calories cut will also mean muscle loss.

Calculating RMR for muscle gain. Conversely, if you are trying to gain muscle then you will require a calorie surplus against your RMR calculation. For example, if your RMR is 2,000 calories + daily activity level calories of 500, then a 10% calorie surplus will mean that you need to roughly eat 2,750 calories a day to ensure you are in a caloric surplus. A surplus of between 10% to 20% is recommended for muscle gain — too many extra calories will also mean fat gain.

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

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