Board Foot Calculator

How to Use This Calculator

Enter your lumber dimensions using the nominal size printed on the board label. For a 2×4, enter 2 for thickness and 4 for width. Length goes in feet: enter 8 for an 8-foot board. Set quantity to the number of boards in your order. The result shows board feet per piece and total board feet. Enter a price per board foot to get a cost estimate. For projects with multiple board sizes, run the calculator once per size and add the totals. Use the quick-pick buttons below the inputs to load common sizes without typing. The formula is the same for softwood framing lumber and hardwood stock; only the price per board foot differs.

How to Calculate Board Feet

Formula: Board Feet = (Thickness × Width × Length) ÷ 12. Thickness and width are in nominal inches. Length is in feet.

Example: a 2×4 that is 8 feet long. Board Feet = (2 × 4 × 8) ÷ 12 = 64 ÷ 12 = 5.33 board feet per piece.

For 10 boards: 5.33 × 10 = 53.3 total board feet. At $4.50 per board foot, that order costs $239.85.

Common board foot counts per piece: 1×4×8 = 2.67 BF. 1×6×8 = 4.00 BF. 2×4×8 = 5.33 BF. 2×6×8 = 8.00 BF. 2×4×10 = 6.67 BF. 4×4×8 = 10.67 BF.

One important note: lumber dimensions are nominal, not actual. The board labeled 2×4 measures 1.5 inches by 3.5 inches after milling and drying. Board foot calculations commonly use nominal or rough lumber dimensions, especially when pricing hardwoods and rough-sawn stock. Hardware stores price dimensional softwood by the linear foot rather than the board foot, so this formula matters most when buying hardwoods, rough-sawn lumber, or comparing different species.

Lumber Tips

Buy 10 to 15 percent extra for waste. Rough-sawn hardwood boards are rarely perfectly flat; cupped, bowed, or twisted boards lose material during jointing and planing. Budget 10 percent extra for straight-cut projects and 15 percent for work with angled joints or many short pieces.

Nominal vs. actual dimensions affect weight and volume, but not board foot pricing. Hardwood dealers commonly quote lumber by the board foot, often based on rough or nominal dimensions before final surfacing. After milling the wood square, you get less actual wood, but the purchase price was based on the pre-surfaced measurements.

For large orders, ask whether the dealer offers MBF pricing or volume discounts. Some suppliers offer better pricing for larger quantities, so it is worth asking before placing a big order.

Check moisture content before buying hardwood for furniture or interior trim. Kiln-dried stock at 6 to 8 percent moisture is ready for use. Air-dried lumber at 12 to 15 percent needs 2 to 4 weeks to acclimate in your shop before milling, or it will move after you cut it.

What to Buy

For framing and general construction: buy dimensional softwood (SPF, Douglas fir, Southern yellow pine) at any hardware store. These are priced by the linear foot and sold in standard 8, 10, 12, 14, and 16-foot lengths.

For furniture, cabinets, and finish work: buy from a hardwood dealer or lumber yard. Common species include red oak, hard maple, walnut, cherry, and poplar. Rough-sawn hardwood is sold by the board foot in standard nominal thicknesses: 4/4 (1 inch), 5/4 (1.25 inches), 6/4 (1.5 inches), and 8/4 (2 inches). Expect $4 to $20 or more per board foot depending on species and grade.

For posts, beams, and heavy timber: contact a local sawmill. Green lumber from a local mill costs 30 to 60 percent less than kiln-dried stock from a dealer. Factor in drying time if buying green.

Frequently Asked Questions