About Water Softener Size Calculator — Neutral Grain Sizing
Who runs Water Softener Size Calculator, why it is brand-neutral, where every formula and compensation factor comes from, and how images are credited.
Why this site exists
Softener shopping has a measurement problem: every brand's own sizing tool runs the math toward its own product line, so one brand's "recommended size" isn't comparable to another's — and every dealer calculator in the search results ends at a product page. This site is deliberately brand-neutral: the same published sizing method applies to every softener, and we show the work so you can compare on spec, not marketing.
InferredHow the numbers are produced
- One formula, one source of truth. The sizing chain (hardness × water use → daily grains → rated capacity → market tier), the iron and manganese compensation, and every unit conversion live in a single module of this site's code. The calculators, the homepage quick table, the sizing chart and the machine-readable summary for AI tools are all generated from that one module — there is no second place where the math could drift.
- Every constant has a source and a date. The 75 gal/person/day water-use basis traces to EPA WaterSense data; the +4 gpg-per-ppm iron compensation is the SoftPro/Nelsen convention; the 0.75 usable-capacity factor reflects rated-vs-real salt settings; the hardness classes are the USGS scale (Durfor & Becker, 1964); 1 gpg = 17.1 mg/L. Each figure carries a footnote-level source tag with its verification date.
- Honest uncertainty. Where a value is an editable default rather than a measured fact — your daily gallons, for example — the page says so in place. Nothing on this site is invented to sound authoritative.
What this site is not
Not affiliated with, endorsed by, or sponsored by any water softener manufacturer or dealer. Calculator results are estimates for information only — real sizing also depends on your tested water (a strip or lab test beats any zip-code guess), and the manufacturer datasheet for the exact model you buy always wins.
Image credits
Photography on this site is used under Creative Commons licenses with attribution:
- Hero photo: Shixart1985, CC BY 2.0 via Wikimedia Commons (left edge cropped)
- Kettle photos: Lee Haywood, CC BY-SA 2.0 and Alexander Davronov, CC BY-SA 4.0
- Water heater photo: Henna, CC BY-SA 1.0
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Contact
Questions, corrections or source disputes are welcome — see the contact page. If you believe a figure here contradicts its cited source, that is exactly the report we want.
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