Scape
Math
Metric
US
Water hardness & alkalinity converter
KH / alkalinity
GH / general hardness
GH from Ca & Mg
Alkalinity / KH reading
Unit
dKH (German degrees)
ppm (mg/L) as CaCO₃
meq/L (mmol/L)
dKH
–
ppm as CaCO₃
–
meq/L
–
As bicarbonate
–
General hardness / GH reading
Unit
dGH (°dH, German degrees)
ppm (mg/L) as CaCO₃
mmol/L
meq/L
grains per US gallon (gpg)
°fH (French degrees)
dGH
–
ppm as CaCO₃
–
mmol/L (Ca + Mg)
–
Also
–
USGS class
–
Calcium (Ca)
from a test or water report
mg/L
Magnesium (Mg)
mg/L
GH
–
ppm as CaCO₃
–
mmol/L (Ca + Mg)
–
USGS class
–
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. Method, worked examples and sources on the full page.