Water hardness unit converter
Use the unit on your supplier report or hardness test. Then compare the converted number with your appliance’s own manual.
Enter a non-negative total hardness result to see the conversions.
These are equivalent units, not new tests. Do not enter calcium alone, conductivity or a TDS-meter reading. Rounded conversions can differ slightly from supplier tables.
Worked example
264 mg/l as CaCO₃ is approximately 2.64 mmol/l, 14.78 German degrees, 26.40 French degrees or 18.48 Clark degrees. These all describe the same hardness.
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Conversion basis: Wessex Water’s household hardness units. This tool does not select a model-specific appliance setting.