At the current one-time price of about $45 per cartridge and a 60–90 day interval, annual replacement spend is roughly $180 to $270 before discounts. Subscription pricing can reduce that materially.
One-time cartridge pricing
Filterbaby currently lists the Pro replacement cartridge around $45 one-time. The company recommends replacement every 60–90 days depending on water quality and usage.
That produces a simple annual range of four to six cartridges.
Annualized cost
Four cartridges at $45 equals about $180 per year. Six cartridges equals about $270 per year.
A household with cleaner water and moderate use may land closer to the lower end, while heavy use or faster fouling can push replacement frequency upward.
Subscription economics
Filterbaby offers lower subscription pricing and multi-pack discounts. The value depends on whether the user actually needs the advertised replacement cadence and is comfortable with recurring deliveries.
Compare the system, not just the hardware price
A $100–$140 faucet device can look inexpensive next to under-sink filtration, but three years of cartridges can cost several times the initial hardware price.
That does not make the system poor value; it simply means recurring cost belongs in the purchase decision.