Guides

Short, practical explanations that answer the search query quickly, then link to the matching free calculator and iPhone app.

Roofing & rafters

Work out common rafter length from span and pitch or rise and run.

Convert an X/12 pitch into rafter length for a known run.

The core formula carpenters use for common rafter layout.

What X/12 pitch means and how it relates to angle.

Estimate bag count from pour volume and bag yield.

Estimate bags for round post-hole footings.

How bag size changes count for the same pour.

Cubic feet and yards for rectangular slabs.

Find riser height, tread depth, and unit count from total rise.

Translate rise/run math into a stringer cut layout.

Use the classic lumber board-foot formula.

Add and subtract construction measurements without decimal mistakes.