This page explains how we build and check every calculator on MathForBuilders.
1. Standard formulas
Each calculator uses the standard formula for the job (for example, board feet = T × W × L ÷ 12, cubic yards = cubic feet ÷ 27) and shows that formula on the page.
2. Hand-checked test cases
Before a calculator goes live, we compare its output to worked examples calculated by hand, such as a 2×4×8 = 5.33 board feet or a 6/12 pitch = 26.57°.
3. Clear assumptions
When a result depends on an assumption (material density, door size, waste factor), we state the default and let you change it.
4. Code references
Where building codes apply, we reference the model code (such as the IRC) and remind you that local codes may differ.
5. Corrections
If you spot an error, please tell us. We review and update pages, and show the last-updated date.