Methodology / worked examples
FilterProof guide
Start from the exact appliance model, then compare only facts you can support: connection, rated capacity, cartridge life, and a price you entered.
Record the reference before shopping
Copy the model and installed filter reference from the nameplate, manual, or cartridge. A family name or a retailer search phrase is not an exact model confirmation.
Use three compatibility outcomes
Incompatible means an entered fact conflicts. Unknown means a needed fact is missing or the exact model is not confirmed. Compatible is reserved for rows you marked yes for exact model match that pass all entered checks.
Compare annualized cartridge cost
The annualized cost is a simple planning comparison and does not include installation, shipping, tax, or changed replacement behavior.
Annualized cost = entered price × 12 ÷ entered life months
A $24 cartridge with a six-month life annualizes to $48 per year. That figure is not a purchase quote.
Limits and assumptions
- There is no product catalog, retailer feed, affiliate link, or real-time price lookup. You supply every candidate row.
- Unknown means a required fact was not confirmed. It is never treated as compatible.
- Compatibility depends on the exact appliance model, installation geometry, certification, and manufacturer instructions. Confirm those outside this tool.