Board Foot Calculator

Quick Answer

Last updated: 2 November 2026 ·How we calculate this: standard board foot formula

How This Board Foot Calculator Works

Hardwood lumber is often priced by the board foot, a unit of volume. Enter the size and number of each board, up to three sizes, and the calculator gives the total board feet and an estimated cost.

How to Use the Board Foot Calculator

1. Enter the thickness and width of Board 1 in inches, and its length in feet.
2. Enter how many boards of that size you need.
3. Add up to two more sizes as Board 2 and Board 3, or leave their quantity empty.
4. Optionally, enter a price per board foot and an extra percentage for waste.
5. Press Calculate to see total board feet, cubic feet and the estimated cost.

Core Formulas

• Length in feet: T × W × L ÷ 12
• Length in inches: T × W × L ÷ 144
• Total: board feet × quantity
• Cost: total board feet × price per board foot

Key Terms

• Board foot: a volume of 144 cubic inches, such as 1 in × 12 in × 1 ft.
• Nominal size: the name size of a board, such as 2 × 4, before drying and planing.
• Actual size: the real measured size, such as 1.5 × 3.5 in for a 2 × 4.
• Quarter system: hardwood thickness in quarters of an inch: 4/4 is 1 in, 8/4 is 2 in.
• S4S: surfaced four sides, meaning the board is planed smooth on all four faces.

Worked Example

You need four oak boards, 1 inch thick, 8 inches wide and 10 ft long, at $6 per board foot.

• One board = 1 × 8 × 10 ÷ 12 = 6.67 board feet
• Four boards = 26.67 board feet
• Cost = 26.67 × $6 = $160.00

Real-Life Examples

• A dining table top: six walnut boards at 8/4 (2 in) thick, 7 in wide and 7 ft long are 49.00 board feet. At $14 per board foot, that is about $686.00.
• Bookshelves: eight 1 × 10 boards, 8 ft long, are 53.33 board feet.
• A workbench frame: ten 2 × 4 boards at 8 ft are 53.33 board feet.
• Comparing prices: a 1 × 6 × 8 board priced at $16 is 4 board feet, so it costs $4 per board foot.

Board Feet vs Linear Feet

• Board feet: measure volume. Used mostly for hardwood sold in random widths and lengths.
• Linear feet: measure length only. Used for trim, molding and many softwood boards sold in set sizes.
• Converting: board feet = linear feet × thickness (in) × width (in) ÷ 12.

Board Feet in Common Lumber Sizes

Based on nominal size.

Nominal and Actual Sizes

• Softwood: a 2×4 is about 1.5 × 3.5 inches after planing.
• Hardwood: thickness is often given in quarters, such as 4/4 (1 inch) or 8/4 (2 inches).
• Pricing: suppliers usually price by nominal size, so use that unless told otherwise.

Common Mistakes to Avoid

• Entering length in inches. This calculator uses feet for length.
• Mixing nominal and actual sizes. Use the size your supplier prices by.
• Forgetting waste. Knots, splits and cutting often use 10% to 20% extra.
• Ignoring rough thickness. Rough boards lose thickness when planed.
• Rounding each board. Add exact board feet first, then round the total.

Frequently Asked Questions

References & Sources