Water Softener Size Calculator
Answer a few questions to find the right grain capacity for your home.
Your details
Grains per gallon — find it on your utility report
Default is 75 gal/person/day.
Each 1 ppm iron adds 5 gpg of effective hardness.
Your result
Recommended size: 24,000 grains
Water classification
Hard (171 mg/L)
How we calculated this
Daily grains = 10 gpg (effective) × 4 people × 75 gal = 3,000
Weekly grains = 3,000 × 7 = 21,000 grains
Sizing step: smallest standard capacity ≥ weekly grains
Estimated salt usage (typical household)
~12 bags/year (40 lb each), $60–$300/yr
Sizing note
Choosing a smaller unit forces frequent regeneration, reducing efficiency, while a grossly oversized unit wastes salt and may not regenerate often enough to keep the resin bed healthy.