Accurate BMR Calculator

Accurate BMR Calculator

Basal Metabolic Rate

This may be the most accurate BMR Calculator with body fat 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.

BMR 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 BMR as it's the minimum for a healthy functioning body.

BMR vs TDEE?

Your BMR (Basal Metabolic Rate) and TDEE (Total Daily Energy Expenditure) differ slightly in that your TDEE calculation is your BMR 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 BMR?

There are two formulas we use in this accurate Basal 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 BMR 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.

BMR calculations and why calculating BMR is important

The single most important reason for calculating BMR 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 BMR for fat loss. If you are trying to reduce the amount of body fat then you will require a deficit against your BMR calculation. For example, if your BMR 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 BMR for muscle gain. Conversely, if you are trying to gain muscle then you will require a calorie surplus against your BMR calculation. For example, if your BMR 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 BMR calculation examples are when combining nutrition with resistance and cardio training for maximum benefit — and don't forget your BMR does not include the calories you burn through your daily activity.

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