We show the math because estimates should be inspectable.
Every calculator separates exact math from practical purchase rounding, documents its assumptions, and has a direct path for reporting something that looks wrong.
Exact result vs. what to buy
Those are two different numbers and the interface treats them that way. If a mulch bed mathematically needs 3.7 cubic yards, the calculator recommends 4 cubic yards after an allowance and a rounding rule. Both are shown, and the allowance is stated next to the result rather than folded invisibly into it.
Assumptions live on the page
Coverage rates, standard deductions, waste percentages, package sizes and rounding rules appear near the calculation and again in the method note at the foot of each calculator. If an assumption materially affects the answer, it cannot be buried only in source code.
Not every result deserves fake precision
Volume calculators can be precise about geometry. A moving-box estimate cannot know how many books, shoes or mysterious cables live in a person’s closet. Those tools present a planning estimate and say so plainly.
Review and maintenance policy
The site is built for low-touch maintenance without becoming abandoned. Availability checks run daily. Known-input “golden” calculations run on every deployment and weekly thereafter. A monthly review covers calculator health, analytics anomalies, search visibility, stale review dates, broken links, browser errors and user-submitted problem reports.
Analytics are useful for detecting that behaviour changed. They are not enough to prove the math is correct — formula correctness is checked with deterministic test cases that live beside the formula itself.
Review dates are not refreshed to look current. A date changes only when the formula or the content was actually reviewed.
User problem reports
Every result includes a “Something look wrong?” link. A report carries what you wrote, the page path, and the category you chose. If you tick the box offering it, it also carries the calculation on screen, which is what turns a vague report into something reproducible. Nothing else goes with it — no IP address, no browser details, no identifier — and product analytics never receive your measurements, prices or free text. Theprivacy note lists it field by field.
Advertising rules
Ads never sit between an input and the Calculate button, or between Calculate and the result. Desktop rail space is reserved before loading, and inline ads begin only after the complete result and its actions, so layout shift cannot interfere with the task.
What this site will not calculate
The scope is material planning. Structural beam sizing, electrical service and load sizing, gas sizing, foundation engineering and similar safety-critical engineering decisions are deliberately out of scope.
Corrections
If a formula or an editorial assumption changes, the calculator’s test cases, its review date and the explanatory copy change in the same release. A correction should never silently rewrite history in a way that makes a previous result impossible to explain.