# Calculator methodology

Every BRIX calculator shows its formula and a worked example on the page. The math lives in small, tested functions, and the worked example printed on each page is computed by the same function, so the explanation and the result can never disagree.

## How the calculators are built

- Each calculator's math is a pure function with automated tests that cover the worked example shown on the page.
- Default inputs are realistic examples, not benchmarks. Replace them with your own numbers.
- Results update as you type and are saved in the page URL, so you can bookmark or share them.
- Nothing you type is sent to BRIX. The calculators run in your browser.

## Tax and rate figures

Calculators that use government figures, such as the IRS standard mileage rate, Social Security wage base or Section 179 limits, read them from one dated configuration file with links to the IRS source. Those calculators give estimates, not tax advice.

## Rules of thumb

Trade estimating tools such as HVAC tonnage or pipe sizing estimators are labelled as rough estimates. They are not a substitute for a Manual J load calculation, an engineer, or your local code official.

See all [free calculators](https://www.brix.so/tools).

## Related

- [About BRIX](https://www.brix.so/about)
- [Contact BRIX](https://www.brix.so/contact)
- [Editorial policy](https://www.brix.so/editorial-policy)

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Written by BRIX Editorial Team. Last updated 2026-10-12.
Canonical: https://www.brix.so/methodology