Converter
Hardness unit converter
Switch between gpg (common for softener sizing) and ppm / mg/L as CaCO₃ (common on kits and reports).
Conversion factor: 1 gpg ≈ 17.1 ppm
Edit either field—the other updates automatically.
Notes
- Assumes hardness as calcium carbonate (CaCO₃) equivalent.
- Kit rounding and strip color charts are approximate.