Water Softener Sizing Calculator

A softener must hold every grain of hardness your household produces between regenerations - which means the size is set by usage times hardness times interval, plus a safety reserve.

Water Softener Sizing Calculator turns household water use, hardness and iron into a grain capacity and a matching standard softener size.

• Hardness: Grains per gallon or ppm input.
• Iron factor: Adds resin-consuming grains.
• Usage: Occupants and gallons per person.
• Regeneration: Interval and reserve days.
• Capacity: Required grains and nearest standard size.
• Salt: Estimated salt per regeneration.
• Export: Text, CSV or JSON report.

1. Enter occupants and daily use per person.
2. Add hardness in gpg or ppm and any iron.
3. Set the regeneration interval and reserve.
4. Read the required grain capacity and standard size.
5. Export the result if needed.

Example 1. A family of 4 using 80 gallons each a day with 15 gpg hardness needs roughly 4,800 grains a day - a 32,000-grain softener regenerating weekly covers it with room to spare.

Example 2. Adding 1.5 mg/L iron pushes effective hardness toward 22 gpg - the same family needs about 7,000 grains a day and a larger 40,000-grain unit.

• Right size first: Avoid undersized or oversized units.
• Iron aware: Real hardness includes iron.
• Standard sizes: Matches common retail units.
• Salt planning: Salt-per-cycle estimate.
• Free and private: No uploads, no logging.