How it works
A softener removes hardness minerals and regenerates with salt. The total hardness you remove in a year divided by how many grains each pound of salt handles gives your salt use.
Hardness is often reported in mg/L; switch the unit and the calculator converts it to grains per gallon.
Bag price is an example assumption. Efficiency depends on your model and salt-dose setting.
The formula
- Grains per year = hardness (gpg) × gallons per day × 365
- Salt (lb) = grains per year ÷ grains removed per lb of salt
- Bags = ⌈salt ÷ bag size⌉; cost = bags × price per bag
How to use this calculator
- Enter your water hardness from a test or your utility's water quality report.
- Enter daily household water use.
- Enter your softener's efficiency in grains per pound of salt.
- Enter bag size and price to see yearly cost.
Frequently asked questions
How hard is my water?
USGS classifies 0–60 mg/L as soft, 61–120 moderately hard, 121–180 hard, and over 180 very hard. Your utility's annual water quality report usually lists hardness.
Why round up to whole bags?
You buy salt by the bag, so the yearly cost uses whole bags.
Sources
- USGS: Hardness of Water: Soft/moderately hard/hard/very hard classes in mg/L as CaCO₃
- PNNL Building America Solution Center: Water Softeners: NSF/ANSI 44 efficiency rating: at least 3,350 grains per pound of salt
- EPA WaterSense: Statistics and Facts: Average American uses 82 gallons of water a day at home
Sources last checked Oct 21, 2026Written and reviewed by the Tapped Out team against the sources above.How we calculate