This page explains where the figures and formulas on Calculator Palooza come from and where to find the references for each calculator.
How the calculators are built
- Each calculator page shows the formula it uses and the assumptions behind it.
- Where a result depends on a price, rate, density or product figure, the calculator page says where that figure comes from, such as your own quote or the label on the product you buy.
- Worked examples use made-up figures to show the arithmetic. They are not current prices, rates or product data.
Unit definitions
Conversions use exact definitions published by the U.S. National Institute of Standards and Technology (NIST).
- 1 foot = 0.3048 meter exactly. Source: NIST, Revised unit conversion factors (the international foot).
- 1 yard = 0.9144 meter (3 feet). Source: NIST Guide to the SI, Appendix B.8: Factors for units listed alphabetically.
Other conversions follow from these. A cubic yard is 27 cubic feet (3 ft × 3 ft × 3 ft), and a square yard is 9 square feet. Trade units such as the roofing square (100 square feet) are defined on the calculator pages that use them.
Calculator references
Calculators that rely on an outside reference list it in the Sources section at the bottom of the page. Figures taken from manufacturers, suppliers or official publications are attributed there.
Reporting an error
If you think a formula, figure or source is wrong, please tell us through the Contact page. Include the calculator name and the numbers you entered.
Last updated: October 24, 2026.