Lumber & Material
Board Foot Calculator with Waste & Defect Allowance
Estimate board feet for hardwood, softwood, or project packs — including realistic waste, defect, and planing allowances.
Calculator
Higher for FAS, lower for #1 Common.
3/16 in is a common rough allowance; 1/16 in is S4S.
Oak ~44, Maple ~40, Walnut ~38, Pine ~28.
What makes this different
Most online board-foot calculators only do nominal dimensions × length × quantity. This one adds three knobs that matter in the shop: a defect/grading allowance (0–25 %), a planer/jointer surfacing deduction (real shrinkage after milling, default 3/16 in per face), and a kerf-aware waste factor for rip cuts. It outputs both nominal and net-milled board feet, plus a rough weight estimate by species.
Who it's for & when to use it
Ordering hardwood from a lumber yard for furniture, kitchen cabinets, or a small deck; sanity-checking a quote; comparing rough-sawn to S4S lumber.
How to use
- Enter the dimensions of your material or the parameters of your project.
- Adjust the optional knobs (waste factor, kerf, planer allowance) to match your shop practice.
- Click Calculate and read the output. Use the per-item breakdown for ordering, the totals for budgeting.
- Compare the result to your lumber yard's quote — the effective $/BF column is the apples-to-apples number.
Formula: BF = (T × W × L) / 144 × Qty. Defect and kerf waste applied multiplicatively. Planer deduction removes 2 × planer_per_face × width × length from the piece volume before BF conversion.
Notes & tips from the shop
- Board foot is a volume measure (144 in³), not a board area. Two pieces of 4/4 × 6 in × 8 ft and 8/4 × 3 in × 8 ft contain the same BF even though one looks twice as big.
- Defect allowance is not waste from cutting. It accounts for knots, wane, splits, and color variation that you reject at the lumber rack.
- Planer deduction is per face; both faces are milled, so the actual thickness after planing is nominal − 2×(planer per face).
Frequently asked questions
Do I need to include kerf waste for rip cuts?
Only if you intend to rip the boards. For straight-edge-of-the-rack pieces that go straight to the planer, leave kerf at 0. For panels ripped out of larger boards, 5–10 % is more honest than zero.
Why does my lumber yard charge by the piece and not by board foot?
Small yards and big-box stores often price by the piece because they pre-surfaced it. BF pricing is more common for FAS hardwood sold rough.
What is the difference between nominal and net board feet?
Nominal BF uses the rough thickness and width you asked for. Net BF is what is actually left after the planer/jointer has dressed the board — that is the wood you actually build with.
Limitations
Does not account for long-grain warping (bow, cup, crook) during storage; always visually inspect boards before milling. Does not compute shipping weight.
All calculations happen in your browser — nothing you type is sent to a server.