Editorial policy
What a page has to have before it is published
Every calculator page carries the tool first, then the formula in plain words and a table or chart where the topic has one. After that come a worked example with real numbers, questions and answers, and a closed list of the documents its figures come from. Every guide carries the same list. A page without a source list for its figures does not go up; the release check that runs before every deploy fails if one is missing.
Where figures come from
Quantities depend on a handful of physical facts. How much a bag yields, how much a cubic foot of a material weighs, what size a board really is, how deep a layer should be. Those facts are taken from the people who make or regulate the product. They come from manufacturers' product data sheets and installation guides, and from government agencies such as the US Geological Survey and state transportation departments. University extension services and standards bodies such as the American Wood Council supply the rest. Retailers, forums and other calculator sites are read to find gaps in what visitors are offered, and their text is never copied. Each source is listed with the date it was read.
How the math is checked
Every formula lives in code with an automated test suite. Each test has an answer that was worked out separately from the code, with plain arithmetic, before the code was written. The site cannot be built while a test fails. The worked figures on the calculator pages and in the guides were recomputed with the same code the calculators run before the pages went up. A release check then reads every built page for a missing source list, a broken link and the other faults it is written to catch. When two sources disagree about a figure, the page says so and uses the more conservative one for buying.
How the pages are made, and what they never claim
The pages are prepared with AI assistance. The tools read the source documents listed at the end of each page, prepare the text from them and recalculate every number with the calculator code. The text is then checked against the sources and against a list of banned claims. No person has read a page before it is published. The How Many Bags team will read the pages over time, after publication. A page a person has read carries a "read by the team" line with the date in its byline. A page without that line has not been read by a person yet. Every page shows the date it was last updated.
The pages describe arithmetic and published guidance. They do not describe jobs the team has done, tests the team has run on materials, or opinions presented as experience. None of that has happened, and saying otherwise would mislead the person about to spend money. Costs appear as ranges from named documents, with the published figures each range is built from quoted against their document, or as figures the visitor types in.
Money
The site is free to use, carries no advertising today and sells nothing. No supplier, manufacturer or retailer pays for a mention, and the sources listed on each page are chosen for being the primary document, not for any relationship. If Google ads are added later, they will sit in marked positions between sections below each tool, never inside a calculator or near a control. They will never appear on the contact, legal, sitemap or guides index pages. Advertisers will have no say in any figure, source or wording, and the privacy page will describe the cookies involved before the first ad shows.
Corrections
If a figure, a formula or an example looks wrong, write to the address on the contact page with the page and the number. Reports are checked against the sources and the test suite. The page is corrected where the report is right, and its last-updated date changes with it.