Three active calculators that show the working — the assumptions, the sources, and the number you actually asked for. Including, quite often, the number that says don't buy anything.
We don't help people buy products.
We help them avoid buying the wrong ones.
What clean-air delivery rate your room needs, which unit covers it, and what a year of running it costs.
"What size air purifier do I need?"Six questions that match a filter to your documented water problem — or tell you that you don't have one.
"Do I actually need a water filter?"What your bathroom really costs in money, paper, water and hours — plus the care and dignity case.
"Will a bidet pay for itself?"The Ear Math — flying with a small child
How often children really get ear pain on a plane, why a baby can’t “just pop their ears”, and an honest look at every remedy — including the free advice everyone gives that nobody has ever tested. Nothing is sold on that page.
Toilet Health — independent evidence review
Five smart-toilet health monitors, checked against the manufacturers’ own documents and the FDA’s databases. A research page — it reviews evidence, it doesn’t sell you a product.
The Sleep Math (parked — in development)
Parked until we’ve verified specific mattress picks, trial periods and return terms. The tool stays online, but we’re not sending anyone shopping from it yet.
Because most of them are shopping lists wearing a lab coat. You arrive with a question, you leave with a product — and the arithmetic in between was decorative.
We do it the other way round. The maths comes first and the recommendation has to survive it. If your room needs 450 CFM and the biggest unit we list delivers 391, we say so and tell you to buy two, instead of quietly linking the one that fits our commission better. That has actually happened, and it's on the record. Every recommendation we have withdrawn or corrected, with what it cost us →
The air purifier calculator is available as an embeddable widget — one line of code, no cost, no tracking of your readers. If a version of one of the other tools would suit your audience, ask.