Project estimator
List the parts of your project: how many, their finished size and the wood. You get the rough boards and plywood sheets to buy, the board feet by species, how much ends up as offcuts and, with your yard's prices, the cost, ready to print or copy for the trip to the lumber yard.
Shopping list
- Red oak, 4/4 rough: 1 board 6 in × 8 ft (4 bd ft)
- Solid wood
- 4 bd ft
- Plywood
- 0 sheets
- Red oak: parts use 2.08 of 4 bd ft, 48% offcuts
Why: Buy 4 bd ft of solid wood.
Why these numbers?
The situation
1 part line, cut from 6 in wide boards in 8, 10, 12 ft lengths and 4 × 8 ft sheets, with a 1/8 in kerf.
From your input: your parts and the stock you can buy
What that means
3/4 in parts plane from 4/4 rough: the standard surfaced (S2S) size of 4/4 is 13/16 in, the thinnest that is thick enough.
One source: National Hardwood Lumber Association, the hardwood grading rules , sources [1]
So
Red oak: parts ripped side by side where they fit across the board and laid along the lengths take 1 × 8 ft; at 4/4 × 6 in that is 4 bd ft (thickness × width × length in ft ÷ 12), of which the parts use 2.08: 48% offcuts.
Arithmetic: exact by definition
Sources
How the estimate is worked out
Hardwood is sold rough and planed to thickness, so each solid part is cut from the thinnest rough board that planes to its finished thickness under the hardwood grading rules: a 3/4 inch part comes from 4/4 rough, which surfaces to 13/16. The hardwood lumber thickness chart lists every size.
Parts narrower than the boards are ripped side by side, as many as fit across with the saw kerf between them, and the rows are laid along the board lengths your yard sells by the same engine as the cut list calculator. Plywood parts are laid out on 4 × 8 ft sheets by the plywood cut list calculator's engine. Board feet are thickness times width times length in feet, divided by 12, the way the board foot calculator counts them.
The offcut share is real waste from the layout, not a guess. Lumber has knots, checks and wane the layout can't see, so add an allowance of your own for those. Prices vary too much by species, grade and place to give one, so the cost uses yours.