Linear Board Foot Calculator

What is a linear board foot?

The term "linear board foot" (sometimes spelled lineal board foot) is used in woodworking and lumber retail to describe lumber measured in linear feet — the total running length of boards in a project or purchase order. It is not a formally standardized unit like the board foot, but the phrase is widely understood to mean: count the length, not the volume.

When a home center prices 2×4s at "$0.45 per linear foot," they mean the price per foot of board length. Width and thickness are fixed by the nominal size of the board, so only the length is variable. Linear footage is most useful when board dimensions are already known and standardized, and what matters is simply how many running feet of material you need to complete a job.

How to use this calculator

Enter your board dimensions and quantity, and the calculator instantly shows total linear feet, total board feet, and the board feet per linear foot ratio. Here is how each field works:

• Thickness: Enter the board thickness in inches. The field accepts decimals (1.5), fractions (5/4), and mixed numbers (1 1/2). Use the preset chips — 4/4, 5/4, 6/4, 8/4 — to fill in common hardwood thicknesses with one click.
• Width: Enter the board width in inches using the same flexible format. For a nominal 2×6, enter 6 (nominal) or 5.5 (actual).
• Length: Use the split ft and in fields. A 10-foot 6-inch board is entered as 10 ft and 6 in — no need to convert to decimal feet.
• Quantity: Number of boards of this size. Linear feet and board feet both scale proportionally with quantity.
• Pricing (optional): Expand the Pricing section to enter a unit price. Choose whether the price is per linear foot, per board foot, or per piece — the calculator will show the total cost and cost per piece.

Linear feet vs board feet

These two units measure different things and are frequently confused — sometimes by lumber yards too:

• Linear feet (LF): Measures only length. Ten 8-foot boards = 80 linear feet, regardless of width or thickness. Width and thickness are completely ignored.
• Board feet (BF): Measures volume — (Thickness × Width × Length) ÷ 12. A 2×6 and a 1×12 are very different amounts of wood even when they are the same length.
• Square feet (SF): Measures face area — length × width — with no regard for thickness. Commonly used for flooring and sheathing.

Use linear feet when ordering trim, decking, or framing lumber priced per running foot. Use board feet when buying hardwood priced by volume, or when comparing pricing across boards of different cross-sections.

How thickness and width affect board feet — but not linear feet

This is the most practically important distinction. Consider two boards, both 10 feet long:

• A 1×6 (nominal) — 10 linear feet, and (1 × 6 × 10) ÷ 12 = 5.00 board feet
• A 2×6 (nominal) — 10 linear feet, and (2 × 6 × 10) ÷ 12 = 10.00 board feet

Both boards are identical in linear footage. But the 2×6 contains twice the wood. If you quote a job in linear feet without specifying the cross-section, nobody knows how much material is actually involved. A framing contractor who orders 500 linear feet of lumber and forgets to specify 2×4 versus 2×6 will end up with either half or double the wood they need.

The board feet per linear foot ratio — (Thickness × Width) ÷ 12 — acts as a conversion factor between the two units for any given board size. The calculator shows this ratio in the results panel so you can use it directly.

Common lumber sizes — linear feet and board feet

Using nominal dimensions. For actual dimensions, use the calculator above.

Pricing lumber: linear foot vs board foot

Where you buy lumber largely determines which pricing unit you'll encounter:

• Home centers and big-box stores typically price dimensional framing lumber, decking, trim, and moulding by the linear foot. The cross-section is fixed (e.g., all 2×4s in a stack), so one price per running foot is unambiguous.
• Hardwood dealers and lumber yards price by the board foot. Because hardwood comes in random widths and thicknesses, board feet captures the actual volume being sold regardless of shape.
• Custom sawyers and timber mills may quote by the board foot, cubic foot, or by the log — always confirm before ordering.

To compare suppliers quoting in different units, convert using the BF/LF ratio for the board size you need:

Price per BF = Price per LF ÷ (Thickness × Width ÷ 12)

For example: 1×6 pine at $0.90 per linear foot. The BF/LF ratio is (1 × 6) ÷ 12 = 0.50. So $0.90 ÷ 0.50 = $1.80 per board foot. Now you can compare that directly against a hardwood dealer's BF price for a similar species.

A practical example

You are building a backyard deck and need 5/4×6 pressure-treated decking boards. The deck requires 15 boards, each 12 feet long. Here is how the numbers work out:

• Total linear feet: 12 ft × 15 boards = 180 LF
• BF per linear foot: (1.25 × 6) ÷ 12 = 0.625 BF/LF
• Total board feet: 180 LF × 0.625 = 112.5 BF

If the home center prices the decking at $0.95 per linear foot: 180 × $0.95 = $171.00

If a competing supplier prices the same species at $1.52 per board foot: 112.5 × $1.52 = $171.00 — the same price expressed in a different unit.

Entering these values into the calculator above (thickness 1.25, width 6, length 12 ft, quantity 15, price $0.95 per LF) gives you the result in seconds and confirms both the quantity and cost before you buy.

When to use linear feet vs board feet

• Use linear feet for decking, fencing, trim, moulding, baseboards, framing studs priced per running foot, and any project where a fixed cross-section is ordered by length.
• Use board feet for hardwood lumber (almost always priced per BF), comparing prices across different dimensions, and calculating total volume for custom milling or drying.

For custom hardwood work, convert to board feet before pricing. For home center framing and trim purchases, linear feet is usually the quoted unit.

Common mistakes when calculating lumber quantities

• Using nominal dimensions instead of actual. A "2×6" is actually 1.5 inches thick by 5.5 inches wide. For board foot calculations this matters: using nominal gives 1.00 BF/LF, actual gives 0.6875 BF/LF — a 31% difference. Always clarify which your supplier is quoting before ordering.
• Forgetting to multiply by quantity. Entering one board's dimensions and reading the result is fine for checking the BF/LF ratio, but total linear feet and total board feet only make sense when the quantity field reflects how many boards you actually need.
• Ordering hardwood by linear feet. Hardwood lumber yards quote in board feet and price that way. If you call a hardwood dealer and say "I need 200 linear feet of 4/4 walnut," they will ask for clarification — or quote you incorrectly. Convert to board feet first.
• Comparing LF prices to BF prices directly. "$1.20 per LF" and "$1.20 per BF" are very different prices. Always convert to the same unit before comparing suppliers.
• Not adding waste overage. Cut waste, defects, and end checks mean you typically need 10–15% more than the net footage calculated. Add your waste factor after calculating the base quantity, not before.

Frequently asked questions

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