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Water Hardness Converter: mg/L, ppm, °dH & °fH

Water companies and appliance manuals use different hardness units. This calculator converts the most common ones to a shared calcium-carbonate basis.

Home Water Tools Water Hardness Converter: mg/L, ppm, °dH & °fH

Convert hardness

200 mg/L ≈ 200 ppm ≈ 11.2 °dH ≈ 20.0 °fH.

What the result means

Hardness categories vary between organisations and suppliers, so use your supplier's terminology when interpreting a local report. The converter is more useful than forcing every result into a universal “hard/soft” label.

Read next: What is hard water? · filters and limescale.

Reviewed: 6 October 2026. Pure Water Guide distinguishes regulatory/public-health guidance from manufacturer claims and general filtration principles. Product performance varies by system and operating conditions.