Water Softener Sizing Calculator
Size your system in seconds. Pick residential or commercial, enter your water details, and we'll recommend the right capacity and point you to matching systems. Need the install/service docs? They're free in our Manuals Library.
Don't know it? 1 ppm = 0.058 gpg; check your water report or test strip.
Residential advice
- Compensate for iron. Every 1 ppm of iron adds ~4 gpg of load — we include this automatically.
- Don't undersize. An oversized softener regenerates less often and uses less salt over its life.
- Metered valves win. Fleck/Clack demand-initiated valves regenerate based on use, not a timer — far more efficient.
- Well water? Treat iron/sulfur with an iron filter first, disinfect with UV, and polish drinking water with reverse osmosis.
Commercial advice
- Flow drives the valve. Size the control valve to your peak gpm so pressure doesn't drop at full demand.
- Need 24/7 soft water? Use a twin-alternating system so one tank regenerates while the other stays online.
- High daily volume means more frequent regeneration — size capacity to your gallons/day and hardness.
- Browse commercial water treatment systems or contact us for a spec'd quote.
Required: download your full results & recommendation as a PDF to save and share.
Frequently asked questions
What size water softener do I need?
Multiply daily water use (about 75 gallons per person) by your hardness in grains per gallon, add iron load, then pick the next standard grain size. This calculator does it for you.
How do I calculate grains of hardness?
Daily grains = people × 75 gallons × hardness (gpg). Each 1 ppm of iron adds about 4 gpg. Size capacity to about 7 days of this load.
Does iron affect water softener sizing?
Yes — iron adds roughly 4 gpg per 1 ppm, so it increases the capacity you need. High iron is better removed by a dedicated iron filter first.