Water hardness converter (GH and KH)
Convert water hardness between German degrees (°dH), ppm CaCO₃, mmol/l and mEq/l.
ppm CaCO₃178
mmol/l1.78
mEq/l3.57
How it’s calculated
Works the same for GH and KH: 1 °dH equals 17.848 ppm CaCO₃. Drop tests usually give °dH; digital meters and tap water reports, ppm or mmol/l.