HardWaterFixFind the fix. Keep the flow.

Free planning tool

Water softener sizing calculator.

Estimate daily hardness demand and a rough capacity range. Confirm the result with a current water test and the equipment maker's usable-capacity chart before purchasing.

Use your test result. If reported as mg/L or ppm as CaCO₃, divide by about 17.1.
Use a measured estimate when you have one; actual use varies.
Iron correction is a rough rule of thumb only. Get a water analysis and follow the chosen system's manual.

Your planning estimate

About 20,000–30,000 grains

Enter your water and household details to update this estimate.

Adjusted hardness used
10 gpg
Estimated daily hardness load
1,800 grains/day
Planning capacity before rounding
15,750 grains

This is not a guarantee of performance and is not a substitute for manufacturer sizing tables. Advertised grain capacity can depend on salt dose, water chemistry, peak flow, reserve settings and the model's actual usable capacity.

How the estimate works

The tool estimates daily load as adjusted hardness multiplied by daily household gallons. It then multiplies by the selected number of days and adds a 20% planning allowance. Some manufacturers use a different capacity rating or recommend other regeneration intervals; compare like-for-like usable capacity and consider professional advice where iron, manganese or high usage complicates the design.

Read the water softener sizing guide and how to test water hardness before buying equipment. A hardness result does not test for bacteria, lead, nitrates or other contaminants.