Board Foot to Linear Foot Calculator

This calculator converts a given volume in board feet to the equivalent length in linear feet, based on the nominal thickness and width of the lumber you specify. Enter the number of board feet, the nominal thickness (in inches), and the nominal width (in inches), and you’ll get the total linear feet required. It also shows the board footage per linear foot for reference.

Formula

The conversion uses the standard definition of a board foot: 1 board foot = 144 cubic inches (12 in × 12 in × 1 in). The formula is:

Linear feet = (Board feet × 12) / (Thickness in inches × Width in inches)

Where:

• Board feet – volume of lumber, in board feet (bd ft)
• Thickness – nominal thickness of the board, in inches
• Width – nominal width of the board, in inches
• Linear feet – length of the board, in feet (ft)

This works because a board foot is a volume unit (1 ft × 1 ft × 1 in), and linear feet is a length unit. Dividing the volume by the cross-sectional area (thickness × width) gives the length.

Worked Example

Using the default values: 100 board feet, 1-inch nominal thickness, 6-inch nominal width.

1. Calculate the cross-sectional area in square inches: 1 in × 6 in = 6 in².
2. Convert the area to square feet: 6 in² ÷ 144 = 0.04167 ft².
3. Divide the board feet by the area in square feet: 100 bd ft ÷ 0.04167 ft² = 2400 ft.

Alternatively, use the formula directly: (100 × 12) / (1 × 6) = 1200 / 6 = 200 linear feet. Wait – that’s different! Let’s recheck.

Actually, the correct step is: 1 board foot = 1 ft × 1 ft × 1 in = 144 in³. So 100 bd ft = 14,400 in³. The cross-section is 1 in × 6 in = 6 in². Length = 14,400 in³ / 6 in² = 2,400 inches = 200 ft. Yes, 200 linear feet.

So the formula gives 200.00 linear feet. The calculator shows 200.00 ft, and the board feet per linear foot is 0.50 bd ft/ft (since 1×6/12 = 0.5).

Why Convert Board Feet to Linear Feet?

Lumber is often sold by the board foot (volume) when you buy rough stock, but projects are planned in linear feet (length) when you need to frame a wall, run baseboard, or cut rafters. Knowing the conversion helps you estimate how many linear feet you can get from a given volume, or conversely, how many board feet you need for a specific length.

For example, if you have 500 board feet of 2×4 lumber (nominal 2 in × 4 in), the linear feet would be (500 × 12) / (2 × 4) = 6000 / 8 = 750 linear feet. That tells you how many 8-foot studs you can cut (about 93, ignoring waste).

How to Choose the Right Inputs

Use nominal dimensions (the size by which the lumber is named, like 2×4) not the actual dressed dimensions (which are smaller, e.g., 1.5×3.5). The board foot system is based on nominal sizes. If you are working with actual dimensions, you can still use them, but the result will differ from standard lumberyard calculations.

For hardwoods and exotic woods, board feet are often measured on the rough green dimension, so ask your supplier what they use. For softwoods (dimensional lumber), nominal is standard.

Common Mistakes and Misconceptions

• Using actual vs. nominal: A 2×4 is not 2 by 4 inches. Using actual dimensions will understate the board feet per linear foot. Always use nominal for standard lumber.
• Forgetting the factor of 12: Because board feet are based on a 12-inch length, you must multiply by 12 in the numerator. Leaving it out gives you a result in “board feet per inchâ€� – not linear feet.
• Mixing units: If you input thickness and width in inches, the formula outputs linear feet. If you input in centimeters, you’ll need to convert to inches first.
• Confusing board feet with square feet: Board feet is a volume measure; square feet is area. A 1-inch-thick board has the same number of board feet as square feet, but a 2-inch board has twice as many board feet per square foot.

When to Use This Conversion

Use this calculator when you:

• Have a lumber order quoted in board feet and need to know how many linear feet of a certain size that represents.
• Are planning a project and need to buy a specific volume of lumber but want to visualize the total length.
• Need to compare prices between suppliers who quote differently (one by board foot, another by linear foot).

Remember that this conversion is purely mathematical – it does not account for waste, defects, or kerf (saw blade thickness). Add 10–20% extra for waste in real projects.

Limitations and Practical Considerations

The formula assumes a perfect rectangular cross-section and no waste. In reality, lumber may have tapered ends, warping, or defects. Also, for boards wider than 6 inches, the nominal width may be the “green� width, which shrinks as it dries. Always confirm with your supplier how they measure.

For plywood and sheet goods, board feet are rarely used; they are sold by sheet (e.g., 4×8). This calculator is for solid lumber only.

Frequently Asked Questions

Q: How many linear feet are in a board foot?
A: It depends on the thickness and width. For a 1-inch by 12-inch board, one board foot equals exactly 1 linear foot. For a 1×6, one board foot equals 2 linear feet (since 12/6=2). For a 2×4, one board foot equals 1.5 linear feet (12/(2×4)=1.5).

Q: What is the difference between a board foot and a linear foot?
A: A board foot is a volume unit (144 cubic inches), while a linear foot is a length unit (12 inches). A board foot measures how much wood is in a board; a linear foot measures how long it is. A 1×12 board that is 1 foot long is 1 board foot; a 1×6 board that is 2 feet long is also 1 board foot.

Q: Do I use nominal or actual dimensions for this calculation?
A: For standard lumber, use nominal dimensions (the name, like 2×4). For hardwoods, use the rough sawn dimensions as quoted by the supplier. If you use actual dimensions, the result will be the actual linear feet for that specific piece, but it won’t match how lumber is typically sold.

Q: Can I convert linear feet to board feet with the same formula?
A: Yes, just rearrange: Board feet = (Linear feet × Thickness × Width) / 12. For example, 10 linear feet of 2×6 (nominal) is (10 × 2 × 6)/12 = 10 board feet.

Q: Why does my lumberyard quote me in board feet but my plan is in linear feet?
A: Because board feet reflects the actual volume of wood, which determines cost for rough lumber. Linear feet is more intuitive for framing and trim. Use this calculator to translate between them for your specific board size.

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in bf | Board feet | bd ft | 100 | 0
in th | Nominal thickness | in | 1 | 0
in wd | Nominal width | in | 6 | 0
out lf | Linear feet | ft | bf * 12 / (th * wd) | 2
out bf_per_lf | Board feet per linear foot | bd ft/ft | th * wd / 12 | 2