Board Foot Calculator: Lumber Volume & Cost

Calculate lumber volume before ordering

Enter thickness and width in inches, length in feet, and the number of equal-sized boards. The calculator returns volume before waste, volume with your selected allowance, and an estimated material price when you enter a price per board foot. It does not obtain supplier prices or reserve stock.

The board foot formula

Board feet = thickness (in) × width (in) × length (ft) × quantity ÷ 12

One board foot is 144 cubic inches, or 1/12 of a cubic foot. It measures volume, not floor coverage.

| Example input | Board feet before waste | |---|---| | One board: 1 in × 6 in × 8 ft | 4 BF | | Five boards: 1 in × 6 in × 8 ft | 20 BF | | One board: 2 in × 6 in × 8 ft | 8 BF |

These examples use the stated dimensions, not the actual size of a nominal construction-lumber product.

Rough dimensions, surfaced dimensions, and billing

Use measured actual dimensions for physical volume. To estimate a supplier's invoice, use its billing dimensions and tally rules. Hardwood may be billed using nominal rough thickness after surfacing, but practices vary. Confirm rather than assume.

A 4/4 designation refers to nominal one-inch rough stock, not a guarantee of a finished one-inch part. Ask about minimum finished thickness and flattening allowance. Record whether surfacing is included in the price.

Board feet versus linear feet

A board foot measures volume; a linear foot measures length. For a constant cross-section, board feet per linear foot equal thickness in inches multiplied by width in inches, divided by 12. Only compare prices after confirming the same dimensions and billing basis. Square feet measure area and require a thickness to convert to volume.

Waste allowance is not usable yield

Saw kerf, trimming, defects, color matching, and flattening reduce usable material. Base your allowance on the cut list and boards available. A fixed percentage cannot guarantee enough long, clear pieces.

This calculator adds your chosen percentage to net volume. For example, 20 BF plus 10% gives 22 BF. That differs from assuming 90% yield: 20 divided by 0.90 requires about 22.22 BF of purchased stock. Confirm which approach your estimate needs.

Read how lumber grades affect usable material and where to buy quality lumber before requesting quotes.

Compare delivered material cost

Estimated material cost = board feet including allowance × quoted price per board foot.

Use an actual supplier quote. Add milling, freight, tax, and minimum-order charges that are not included. A low unit price may produce a higher total cost if the boards cannot yield your required parts.

Use Compare Species before choosing a material. For exposed work, read the outdoor furniture buying guide instead of choosing by hardness or price alone.

Weight and technical limits

The optional weight estimate uses the selected profile's recorded dried density. Actual moisture, species variation, and packaging can change shipping weight. Confirm freight weight with the supplier; this is not a structural load approval.

Reference for lumber terminology and measurement context: USDA Forest Products Laboratory, Wood Handbook (2021), Chapter 6: Commercial lumber, round timbers, and ties. Formula examples are arithmetic illustrations, not supplier quotes. Editorial revision: October 15, 2026.