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Board Foot Calculator

Board feet and cost from lumber dimensions.

Your measurementsEvery assumption editable01

Nominal thickness — a 4/4 board is 1 in.

Lumber volumeCalculated live02

Result

40board ft

40 board feet — $180

Board dimensions
1 × 6 in × 8 ft
Per boardthickness × width × length ÷ 12
4 board ft
Number of boards
10
Total volume
40 board ft
Costat $4.5 per board foot
$180

A board foot is a volume — 144 cubic inches, or a piece one inch thick by twelve inches square. It is not a measure of length or of surface area, which is why two boards of the same footage can be very different shapes.

Hardwood is sold by nominal thickness in quarters: 4/4 is one inch, 8/4 is two. That nominal figure is what the board measured rough-sawn, so a surfaced 4/4 board arrives closer to 13/16 in — but it is still sold and calculated as one inch.

Softwood dimensional lumber is normally sold by the piece or the linear foot rather than by board foot, so this suits hardwood and rough stock.

A board foot is a volume — 144 cubic inches — not a length or an area. Enter the dimensions and quantity and this gives the footage and what it costs at your yard's price.

Why use this tool?What it does differently03

Why use this tool?

Volume, not length

Board feet measures wood, so two boards of identical footage can be very different shapes.

Cost included

Hardwood is priced per board foot, so the total is the number you actually take to the till.

Quarter thicknesses

4/4, 8/4 and the rest — enter the nominal figure, which is what you are charged for.

Explains nominal

A surfaced 4/4 board measures nearer 13/16 in, but is still sold as one inch.

How this worksThe method04

How this board foot calculator works

Thickness in inches times width in inches times length in feet, divided by twelve, gives board feet for one piece. The twelve converts the mixed units — it is not a fudge factor.

Hardwood thickness is quoted in quarters of an inch: 4/4 is one inch, 5/4 is one and a quarter, 8/4 is two. That nominal figure is what the board measured rough-sawn and it is what you are charged for, even though surfacing removes some of it.

Softwood dimensional lumber is normally sold by the piece or the linear foot instead, so this calculation suits hardwood and rough stock rather than framing timber.

How to use itStep by step05

How to use it

  1. Step 1: Enter the thickness

    Nominal, in inches. A 4/4 board is 1, an 8/4 is 2.

  2. Step 2: Enter width and length

    Width in inches, length in feet, as the yard measures them.

  3. Step 3: Set the quantity

    How many boards of that size.

  4. Step 4: Add your price

    Per board foot, to get the total. Leave at zero to skip costing.

Example usageWorked figures06

Example usage

A stack of 4/4 stock
Ten boards of 1 in × 6 in × 8 ft is 0.667 board feet each, 6.67 total — about $30 at $4.50 per board foot.
Thicker stock
The same ten boards in 8/4 doubles to 13.33 board feet. Thickness scales the volume directly.
One wide board
A single 1 in × 12 in × 10 ft board is 10 board feet — the same as fifteen 1 × 6 × 8 pieces would be, in one piece.
Frequently asked questionsCommon questions07

Frequently asked questions

What is a board foot?

A volume of 144 cubic inches — nominally a piece one inch thick, twelve inches wide and twelve inches long. It measures wood, not length or surface area.

How do I calculate board feet?

Thickness in inches times width in inches times length in feet, divided by twelve. Multiply by the number of boards.

What does 4/4 mean?

Four quarters of an inch, so one inch nominal thickness. Hardwood is quoted this way; 5/4 is 1.25 in and 8/4 is 2 in.

Why is my surfaced board thinner than nominal?

The nominal figure is what it measured rough-sawn. Surfacing removes material, so a planed 4/4 board arrives around 13/16 in — but it is still sold and calculated as a full inch.

Does this work for framing lumber?

The arithmetic does, but softwood dimensional lumber is normally priced by the piece or the linear foot rather than by board foot.

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