Water Hardness Converter & PPM to dH Calculator (UK Tool)

Water Hardness Converter – Convert PPM, dH, °TH, Clarke & gpg (UK Calculator)

Convert water hardness instantly using our UK-friendly converter. Enter any hardness value in PPM, mg/L, German dH, French °TH, Clarke or US grains per gallon and the tool will calculate all units automatically. Ideal for homeowners, plumbers, heating engineers and facilities teams.

Understanding water hardness is important for homeowners, plumbers, heating engineers and facilities teams, but the terminology—PPM, mg/L, German degrees (°dH), French degrees (°TH), Clarke and US grains per gallon—can be confusing. This tool gives you a clear, instant way to convert between all major hardness units used across the UK and Europe. Whether you’re checking the hardness before choosing a water conditioner, comparing readings from different water suppliers, or trying to understand how hardness levels relate to limescale build-up in your home or commercial system, this converter provides accurate results in one place. Hard water affects everything from boilers and heat exchangers to taps, showers and appliances, and knowing the true hardness level helps you choose the right solution. Simply enter your value in the unit you have, click convert, and the full breakdown appears instantly.