Measure the run, rise or bay you are counting
Studs need wall length and spacing. Joists and rafters need span and spacing. Stairs need total rise and target riser/tread. Decking needs bay size, board width and gap. Board feet needs actual piece dimensions.
- On-centre spacing includes the extra end member in a proper count.
- Sheet goods use selected sheet coverage, not an assumed 32 ft² if you are buying a different size.
- Stair results are planning geometry, not a code-compliant stair design.
Count the system you are buying
Use board feet for billed lumber volume, studs/joists/rafters for member counts, lumber linear for running length, sheet goods for plywood or OSB, decking for deck boards, and stairs for riser/tread/stringer planning.
Pieces, sheets and board feet
Suppliers sell sticks, sheets and board feet. Leave waste visible for cuts, unusable ends and grade fallout.
- Do not treat a joist count as a span rating.
- Hardware, hangers, flashing and fasteners are separate lines.
- Replace any planning price with a dated yard quote.
Planning boundary
These tools estimate counts. They do not perform structural design, span-table selection, lateral design or code approval.