About TrueCalc
A plumb bob doesn't estimate vertical — it proves it. Hang one from a string and gravity does the rest; there's no judgment call, no "close enough." That's the standard this site holds its own calculators to. A calculator that returns a plausible-looking number isn't good enough if the number is wrong — it just means the mistake is harder to catch.
What we build
Single-purpose calculators for construction and materials, pay and pricing, home utilities, and dates. Each one is built to answer exactly one task, quickly: how much sand, what the raise percentage is, how many pavers, how many years apart. No calculator on this site tries to be a general-purpose tool — narrow scope is what makes the formula easy to verify and the page easy to trust.
The standard every calculator has to pass
Before a calculator is published, its formula is checked against a reference source, then run through a minimum of three known-answer test cases — including at least one edge case — plus independent unit-conversion checks and input validation for zero, negative, decimal and unusually large values. The full process is documented on the methodology page, including the exact test case shown as the worked example on every calculator page.
Why the formula is always shown
Every calculator page shows its formula and a fully worked example, not just a results box. That's deliberate — the point isn't to ask you to trust a black box, it's to let you check the arithmetic yourself in under a minute. If the formula on the page doesn't match what you expect for your situation, that's useful information before you rely on the result.
What this site is not
These are general-purpose estimators, not professional advice. Construction quantities don't account for site-specific conditions or your local building code. Pay and pricing figures are gross numbers, not tax or payroll advice. Verify anything with real money, safety or legal consequences against a qualified professional or your supplier's own specifications.
Corrections
If a calculator gives you a result that doesn't match your own math, we want to know — report it here. A formula error is treated as a launch-blocking issue, not a routine content fix.