Board Foot Calculator

How to use this calculator

1. Enter thickness and width as the yard prices them — usually nominal (2×6) for softwood, or rough-sawn quarters (4/4, 8/4) for hardwood.
2. Enter length and the number of pieces.
3. Add a price per board foot to estimate cost; metric mode prices per m³.

Method & assumptions

Board feet = Thickness (in) × Width (in) × Length (ft) ÷ 12 × Pieces
1 board foot = 144 cu in = 0.002360 m³
1 m³ ≈ 423.8 board feet

Nominal vs actual

a 2×6 is about 1½ × 5½ in after drying and planing

Quarter thickness

4/4 = 1 in, 8/4 = 2 in rough-sawn hardwood

Assumptions & limits

• Uses the dimensions you enter; it does not convert nominal to actual automatically.
• No waste factor — add 15–30% for defects when buying rough hardwood.

Rounding: purchase quantities are always rounded up to whole bags, boxes, sheets or bundles. See our methodology.

Worked examples

In depth: board feet planning notes

Nominal versus actual sizes

In North America, softwood framing lumber is named by its nominal size before drying and planing. A 2×4 is actually 1½ × 3½ in, a 2×6 is 1½ × 5½ in and a 1×6 is ¾ × 5½ in. Board feet for softwood are usually calculated from nominal sizes, which is how lumber yards price it. Hardwood is different: it is sold rough-sawn by thickness in quarters — 4/4 is 1 in, 8/4 is 2 in — and board feet are calculated from the rough dimensions.

Our calculator uses whatever thickness and width you enter, so for framing enter nominal sizes; for hardwood enter the rough quarter thickness and the measured width. In metric markets, timber is sold by actual sawn or planed sizes in millimetres, and the calculator converts to cubic metres and board feet so you can compare.

Pricing and yield

Hardwood dealers quote a price per board foot, and the total is board feet times price. Random-width boards are measured individually, then totalled. When you plan a project, buy 20–30% more board feet than the finished parts need: rough lumber loses thickness when planed, edges must be jointed, and defects such as knots, checks and splits need to be cut out.

For metric purchases, timber is often priced per linear metre for a given section, or per cubic metre for bulk orders. One cubic metre is about 424 board feet. Converting quotes to the same unit is the easiest way to compare suppliers.

Board feet measure volume, not strength or grade. Structural uses require graded lumber of the right species and size for the span; consult span tables or an engineer.

Worked comparison of two quotes

Suppose one yard offers 8/4 white oak at a price per board foot and another sells 50 mm oak at a price per linear metre for a 200 mm wide board. To compare, convert the second to board feet: 50 × 200 mm × 1 m is 0.01 m³, which is about 4.24 BF per metre. Divide the price per metre by 4.24 and you have a price per board foot to set against the first quote.

Remember that rough and dressed timber are not equivalent. Dressed boards are already planed, so less of the volume you pay for is lost in the workshop. A slightly higher price per board foot for dressed stock can work out cheaper if you would otherwise lose 15–20% to planing.

Tips & common mistakes

• Ask whether the price is per board foot on nominal or actual size — most yards use nominal.
• Rough hardwood loses about ⅛–¼ in when surfaced; buy thick enough.
• Store lumber flat and stickered so it doesn't warp before use.

Sources

1. USDA Forest Products Laboratory – Wood Handbook — checked 2026-10; verify before launch
2. American Lumber Standard Committee – softwood sizes (PS 20) — checked 2026-10; verify before launch
3. National Hardwood Lumber Association – grading rules — checked 2026-10; verify before launch

Default values (bag yields, coverage rates, densities) are typical figures from manufacturer literature. Always check the label on the product you buy.

Cite or embed this calculator

DIYCalcLab. “Board Foot Calculator.” Oct 18, 2026. https://diycalclab.com/lumber/board-foot-calculator/

An embeddable version for blogs and contractor sites is planned.