About these calculators

Show the work

Every tool prints the formula it uses and a worked example computed by the very same code that powers the live calculator, so the example can never drift from the result. The commodity tools, board feet, lumber cost, cubic feet, and the linear-to-board-feet converter, are simple geometry. The engineering tools, shelf sag and wood movement, rest on standard beam and shrinkage equations.

Where the wood data comes from

Shelf sag and wood movement depend on measured material properties: the modulus of elasticity for stiffness, and the tangential and radial dimensional change coefficients for movement. We carry a grounded value for 117 woods and panels, drawing on 119 distinct cited sources. The primary references are the USDA Forest Products Laboratory Wood Handbook (GTR-282), The Wood Database, the published wood movement tables, and panel specifications for sheet goods.

Where a value is an estimate rather than a sourced constant, mainly indicative lumber prices and a few sheet-good densities, it is labelled as such on the species page. Prices are rough guides for planning, not quotes.

Limits

These calculators are for planning and estimation. Engineering results (shelf sag, wood movement) use published average material properties; real boards vary by grade, grain, moisture and defects. Verify load-bearing designs with a professional.