What hardness measures
Water hardness mainly reflects dissolved calcium and magnesium. These minerals affect scaling, soap performance, treatment requirements, and aquarium chemistry.
Hardness is often reported as mg/L or PPM as calcium carbonate, written as CaCO3.
Why CaCO3 equivalents are used
Calcium and magnesium have different chemical weights. Reporting both as CaCO3 equivalents creates a common basis for comparison.
The calculator uses standard conversion factors to estimate hardness from calcium and magnesium concentrations.
How to interpret the result
The result is not the same as calcium concentration alone. It is a combined hardness value that expresses mineral contribution as CaCO3.
Frequently asked questions
Is hard water unsafe?
Hardness is usually an aesthetic and operational concern, but interpretation depends on the use case and local guidance.
Why are calcium and magnesium both needed?
Both ions contribute to hardness, so using only one can understate the total value.