Choose a cation-to-anion ratio or reverse charge calculation, water ion balance, or feed DCAD. Use measured concentrations and the stated reporting basis; these calculations do not establish water or ration safety.

Use total positive and negative charge on the same meq/L basis.

Related Calculators

Cation to Anion Ratio Formula

The following formula is used to calculate the cation to anion ratio:

CAR = Cation Charge / Anion Charge

Variables:

  • CAR is the cation to anion ratio
  • Cation Charge is the total charge of cations in milliequivalents per liter (meq/L)
  • Anion Charge is the total charge of anions in milliequivalents per liter (meq/L)

To calculate the cation to anion ratio, divide the total cation charge by the total anion charge. The result is a dimensionless number that represents the balance between positively charged ions (cations) and negatively charged ions (anions) in a solution.

What is a Cation to Anion Ratio?

The cation-to-anion ratio compares measured positive and negative charge totals. Together with signed charge balance error, 100 × (C − A)/(C + A), it can screen analytical consistency. It does not by itself predict reactions, water safety, scaling, corrosion or chemical stability. Water mode converts mg/L to meq/L using rounded equivalent weights. Optional blanks contribute zero, so include known major ions and avoid double-counting alkalinity. Feed DCAD uses (Na + K) − (Cl + S) equivalents on a dry matter basis, reported in meq/kg DM; it is not a ration or supplementation recommendation.

How to Calculate Cation to Anion Ratio?

The following steps outline how to calculate the Cation to Anion Ratio:

  1. First, select Cation-to-anion ratio and enter total cation charge (meq/L).
  2. Next, determine the total anion charge in the solution (meq/L).
  3. Use the formula CAR = Cation Charge / Anion Charge.
  4. Finally, select Calculate. The example totals of 50 and 40 meq/L give a ratio of 1.25 and a signed charge balance error of about 11.111%.
  5. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem:

Use the following variables as an example problem to test your knowledge.

Cation Charge (meq/L) = 50

Anion Charge (meq/L) = 40