Enter the milligrams (mg) of substance, valence, and molecular weight into the calculator to determine the mEq.

mEq Formula

The following formula is used to calculate the milliequivalent (mEq) of a substance. 

mEq = mg * V / MW
  • where mEq is the milliequivalent
  • mg is the milligrams of substance
  • V is the valence of the substance
  • MW is the molecular weight of the substance

To calculate mEq, multiply the milligrams by the valence of the substance, then divide by the molecular weight of the substance.

mEq Definition

mEq is short for milliequivalent. The milliequivalent is a measure of the combining power of an element relative to the activity of 1 mg of hydrogen. This term is most often associated with electrolytes.

Example Problem

How to calculate mEq?

  1. First, determine the mg of the substance.

    In this example, there is a total of 25mg of substance.

  2. Next, determine the valence.

    The valence of this material is 3.

  3. Next, determine the molecular weight.

    The molecular weight is found to be 40 mg/mol.

  4. Finally, calculate the mEq.

    Using the formula above, the milliequivalent is calculated to be:
    mEq = mg * V / MW
    mEq = 25*3/40
    mEq = 1.875