Linear Feet to Board Feet Calculator

This calculator converts a length measured in linear feet into board feet, which is a volume measurement used for lumber. You enter the length in feet, the width in inches, and the thickness in inches, and it returns the volume in board feet (and cubic feet). One board foot equals 144 cubic inches, or 1 ft × 1 ft × 1 in.

Formula

The standard formula for board feet is:

Board Feet = (Length in feet × Width in inches × Thickness in inches) ÷ 12

Where:

• Length is measured in feet (ft).
• Width is measured in inches (in).
• Thickness is measured in inches (in).
• 12 is the conversion factor because one board foot is 1 ft × 1 ft × 1 in, and 1 ft × 1 ft × 1 in = 144 in³, but since length is already in feet, dividing by 12 converts the width×thickness product from square inches to board feet.

If you prefer to work entirely in inches, the equivalent formula is:

Board Feet = (Length in inches × Width in inches × Thickness in inches) ÷ 144

Both give the same result; the first is more convenient when your length is already in feet.

Worked Example

Using the default values from the calculator: length = 12 ft, width = 6 in, thickness = 1 in.

1. Multiply length × width × thickness: 12 × 6 × 1 = 72.
2. Divide by 12: 72 ÷ 12 = 6.
3. The result is 6 board feet.

The calculator shows the same answer: 6.00 bd ft. The volume in cubic feet is 12 × 6 × 1 ÷ 144 = 0.50 ft³.

Why Use Board Feet Instead of Linear Feet?

Linear feet simply measures length along a straight line. A 10-foot 2×4 and a 10-foot 2×12 both have the same linear footage, but the 2×12 contains six times more wood. Board feet accounts for thickness and width, giving a true measure of wood volume. This matters when you are buying lumber, estimating shipping weight, or comparing prices between different sizes. Sawmills and lumberyards price hardwood and softwood by the board foot, not by the piece or by linear foot, so knowing how to convert is essential for accurate budgeting.

How to Measure for the Calculator

To get an accurate board foot figure, you need three dimensions:

• Length: Measure the longest side of the board in feet. If your board is 8 feet 6 inches, enter 8.5 (since 6 inches = 0.5 ft).
• Width: Measure across the face of the board in inches. For a 2×4, the nominal width is 4 inches, but the actual width is about 3.5 inches. Use the actual width for the most precise volume.
• Thickness: Measure the narrow dimension in inches. A 2×4 is nominally 2 inches thick, but actually 1.5 inches. Again, use the actual thickness if you want real volume.

If you have multiple boards of the same size, calculate one board and multiply by the number of boards. For mixed sizes, calculate each group separately and add the totals.

Nominal vs. Actual Lumber Sizes

A common point of confusion is the difference between nominal and actual dimensions. A “2×4� is not 2 inches by 4 inches; after planing and drying, it measures about 1.5 × 3.5 inches. Similarly, a “1×6� is about 0.75 × 5.5 inches. When you buy lumber, you are usually charged for the nominal size, not the actual size. This means a 12-foot 2×4 is sold as 8 board feet (12 × 4 × 2 ÷ 12 = 8), even though the actual volume is only 6.125 board feet (12 × 3.5 × 1.5 ÷ 12 = 6.125). For rough lumber (unfinished), the nominal size matches the actual size. Always ask your supplier whether the price is based on nominal or actual dimensions.

Common Mistakes and How to Avoid Them

• Mixing units: The formula requires length in feet and width/thickness in inches. If you measure length in inches, use the ÷144 version. Mixing them will give a result off by a factor of 12.
• Forgetting to convert inches to feet for length: If your board is 6 feet 6 inches, entering 6.6 instead of 6.5 will overstate the length.
• Using nominal vs. actual: For finished lumber, decide which you want and stay consistent. For pricing, nominal is standard; for true volume, use actual.
• Rounding too early: Do the full calculation then round to the nearest board foot (or tenth). Rounding each dimension first can shift the result by several percent.

Limitations of the Board Foot Calculation

The board foot formula assumes a perfectly rectangular, straight board. Real lumber may have taper, warping, or irregular edges, which reduce usable volume. For rough-sawn lumber, the nominal dimensions are usually close to actual, but for kiln-dried and planed boards, the difference is significant. Also, the formula gives volume, not weight. Different wood species have different densities, so two boards with the same board footage can weigh very differently. If you are estimating shipping costs, you will need to multiply the board feet by the species’ density (pounds per cubic foot) and then convert to weight.

Frequently Asked Questions

How many linear feet are in a board foot?

There is no fixed answer because it depends on the width and thickness. A 1×6 board has 0.5 board feet per linear foot (6 × 1 ÷ 12 = 0.5). A 2×4 has 0.667 board feet per linear foot (4 × 2 ÷ 12 = 0.667). To find linear feet from board feet, divide the board feet by (width × thickness ÷ 12).

What is the difference between a board foot and a cubic foot?

A cubic foot is 12 × 12 × 12 = 1,728 cubic inches. A board foot is 144 cubic inches. Therefore, one cubic foot equals 12 board feet. The calculator shows both so you can compare.

Do I use nominal or actual dimensions for pricing?

For finished (planed) lumber, most suppliers price by nominal dimensions. For rough lumber, nominal equals actual. Always confirm with your supplier. If you are calculating for a project that needs exact wood volume, use actual dimensions.

Can I use this calculator for hardwood flooring?

Yes, but flooring is often sold by the square foot, not board foot. To get square feet, multiply length (ft) × width (in) ÷ 12. This calculator gives volume, so you would need to divide by the thickness in inches to get square feet. For example, 6 board feet of 1-inch-thick material equals 6 square feet.

How do I calculate board feet for a log?

Logs are not rectangular, so the simple formula does not apply. The Doyle or Scribner log rules estimate board feet from log diameter and length. Those rules are more accurate for round logs and are used in timber cruising.

What is a “thousand board feet� (MBF)?

MBF stands for “one thousand board feet.� It is a common unit for selling large quantities of lumber. To convert, divide your board feet by 1,000. For example, 6,000 board feet = 6 MBF.

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in l | Length | ft | 12 | 0 | 1000
in w | Width | in | 6 | 0 | 48
in t | Thickness | in | 1 | 0 | 12
out bdft | Board Feet | bd ft | l * w * t / 12 | 2
out ft3 | Volume | ft³ | l * w * t / 144 | 2