Meq and mmol Calculation Information

 

For a web-based calculator for electrolytes, click here.

 

Basic meq and mmol calculations:

mmol = molecular weight (MW) in mg

1meq = 1mmol # of charges

Charges is defined as the total number of positive OR negative charges, but NOT

positive and negative charges added together.

 

Example:

Ca++ gluconate- - (MW = 430)

1 mmol of calcium gluconate = 430mg

Ca gluconate has two positive and two negative charges

1meq Ca gluconate = 430mg 2 = 215mg

        When converting mg to meq, the number of meq to mmol is the number of charges.

For example, in the case of Ca gluconate, there are 2 meq for every mmol

because there are 2 charges. (1mmol = 430mg; 430mg/215mg = 2meq;

1mmol = 2meq of Ca gluconate)

 

 

More about the molecular weight:

 

        The molecular weight may be more than just the salt youre using. For

example, magnesium sulfate (Mg++SO4- -; MW = 120.36) is available

commercially as magnesium sulfate heptahydrate (Mg++SO4- -7H20;

MW = 246.47). In this case, you would use the molecular weight of

magnesium sulfate heptahydrate since that is what you actually have.

 

Mmol and meq of Phosphates:

 

NaPO4 and KPO4 exhist as a mixture of monobasic and dibasic (monobasic KPO4

and dibasic K2PO4

3mmol of NaPO4 = 4meq of NaPO4

3mmol of KPO4 = 4.4meq of KPO4

mmol is used to express the phosphate and meq used to express Na or K

        Because of dibasic form, there will be more Na or K than PO4. Therefore, meq will

always be the larger number.

3mmol of KPO4 mixture contains 93mg of phosphorus (MW = 31) (NOT

PHOSPHATE although Im not sure why) and 170.3mg of K (MW = 39.1)

 

170.3mg

1mmol

1meq

=

4.4meq of K

 

39.1mg

1mmol

 

93mg

1mmol

=

3mmol of PO4

 

31mg

 

        3mmol of NaPO4 mixture contains 93mg of phosphorus (MW = 31) (NOT

PHOSPHATE although Im not sure why) and 92mg of Na (MW = 23)

 

92mg

1mmol

1meq

=

4meq of Na

 

23mg

1mmol

 

93mg

1mmol

=

3mmol of PO4

 

31mg