Water hardness converter
Every brewing tradition reports hardness differently — German degrees, English Clark degrees, American grains per gallon. Convert any of them to the units your calculator expects.
How it works
All hardness units are equivalent expressions of the same thing. Anchored to ppm as CaCO₃: 1 meq/L = 50 ppm, 1 °dH = 17.85 ppm, 1 Clark degree = 14.25 ppm, and 1 grain per US gallon = 17.12 ppm. Conversions are exact — the only judgment call is remembering whether your report meant hardness or alkalinity.
FAQ
Which unit is my report using?
US labs report ppm as CaCO₃ or grains per gallon; German reports use °dH; older UK reports use Clark degrees. If a European report says “mval”, that is meq/L.
Is hardness the same as alkalinity?
No — hardness counts calcium and magnesium; alkalinity counts carbonate buffering. Both are conventionally expressed as CaCO₃, which is why they get confused. The unit conversions here apply to either.
How do I get the actual calcium ppm from hardness?
If the hardness is all calcium, multiply ppm as CaCO₃ by 0.40. Real water splits hardness between calcium and magnesium, so a full report beats a converted single number.
What counts as soft or hard water for brewing?
Below about 50 ppm as CaCO₃ is soft, 50–150 moderate, over 300 hard. Great beer is brewed across that whole range — what matters is matching water to style, not chasing softness.
Conversion factors from standard water chemistry references, as compiled in the brewwtr formula documentation and verified in its test suite.