How the tools get chosen, how the numbers get checked, and what we do when something is wrong.
This policy covers a site that builds tools rather than reviews products. It used to describe how we researched and ranked products; that whole business was removed from the site, so the policy was rewritten to match what actually happens here now.
How topics are chosen
Tools are built around questions people actually search for, and then judged on a simple test: does having this tool save someone a real piece of work? A percentage calculator earns its place because the question comes up constantly and the answer is fiddly to work out by hand. A tool that only duplicates something the operating system already does well does not, however easy it would be to build.
Reader requests carry a lot of weight. If several people ask for the same converter, that is better evidence of a real need than any keyword volume figure.
How the numbers are checked
The mathematical tools are checked against authoritative definitions rather than against other websites, because other websites are frequently where the errors come from. In practice that means: conversion factors are taken from the defining standard (an inch is defined as exactly 2.54 cm, it is not approximately that), date arithmetic is tested across leap years and month boundaries, and financial calculators are verified against the standard amortisation and compound interest formulas.
Where a tool has a known limitation, the page says so instead of hiding it. The BMI calculator repeats that BMI is a population-level screening measure and not a diagnosis. The unit converter states that it uses US customary gallons, because a UK gallon is a fifth larger and the difference matters in a recipe.
What we do not do
- We do not recommend products. There are no buying guides, no rankings and no “best of” lists on this site. Product roundups were removed because they age badly and are hard to keep honest.
- We do not take payment for placement. Nothing on the site is a sponsored position, because there is nothing to place.
- We do not run a testing lab. We are not claiming hands-on experience with hardware. We build and describe software tools, which we can verify directly.
- We do not collect what you enter. The tools run in your browser. See the privacy policy for the little that does get collected.
AI assistance, stated plainly
The explanatory writing on this site is produced with AI assistance and then reviewed. We are not going to pretend otherwise, because a reader is entitled to know how a page was made and because being vague about it is itself a kind of dishonesty.
What that means for you: descriptions of the tools are reliable, because they describe software we can run and check. Broader claims about the world — conventions, standards, how a field usually works — are researched rather than tested, and should be treated as a starting point rather than a final authority. If a decision is expensive or irreversible, confirm it against a primary source.
Corrections
If a tool gives a wrong answer, that is a bug and we want to know. Email sunfei0318@gmail.com with the tool, the input and what you expected. Errors in the maths get priority over everything else on this site.
Independence and funding
The site is not funded by affiliate commissions, sponsored content or product placement, because it does not carry any of those things. Running costs are covered by the operator. That is worth stating explicitly precisely because so many tool sites are not set up this way, and because a site with a commercial incentive behind each recommendation is a different proposition from one that just answers a question.