Water Softener Sizing & Grain Capacity Calculator

Enter how many people live in your home, roughly how much water you use and your measured hardness. We work out the grains of hardness your home removes each day and recommend a softener big enough to handle it without regenerating too often. The most common and most expensive mistake is buying too small: an undersized unit runs out of soft water, regenerates constantly, burns through salt and wears out early.

Why the load matters: a softener cartridge holds a fixed number of grains of hardness before it has to regenerate with salt. Your daily load is simply how much water you use multiplied by how hard it is. Pick a unit whose working capacity lets it regenerate roughly every three to six days. Regenerating much more often than that wastes salt and water and shortens the resin life; much less often than weekly can let stale water sit in the resin between cycles. Most softeners only deliver about two thirds of their headline grain rating at an efficient salt dose, so we size against working capacity, not the figure on the box.