Skip to content
Calcapedia
Menu
Home & Garden

Board Foot Calculator

Find the board feet in a stack of lumber from its thickness, width, length and piece count, and what it costs at a price per board foot.

Level: Grade 6

  • Common Core standard 6.G.A.2Find the volume of a right rectangular prism with fractional edge lengths by packing it with unit cubes of the appropriate unit fraction edge lengths, and show that the volume is the same as would be found by multiplying the edge lengths of the prism. Apply the formulas V = l w h and V = b h to find volumes of right rectangular prisms with fractional edge lengths in the context of solving real-world and mathematical problems.
  • Common Core standard 6.RP.A.3.dUse ratio reasoning to convert measurement units; manipulate and transform units appropriately when multiplying or dividing quantities.
Printable worksheet

Board Foot Calculator

Know the answer you need? Pick an input to work backward.

Inputs
Measure by

The thickness the board is sold as, such as 2 for a 2×4. Hardwood quarters: 4/4 = 1, 5/4 = 1.25, 8/4 = 2.

The width the board is sold as, such as 4 for a 2×4.

Optional. Leave blank to skip the cost.

Result

Total board feet

40 BF

10 pieces come to 40 board feet, costing about $180.00.

Board feet per piece
4 BF
Wood volume
3.333 ft³
Total length of lumber
80 ft
Total cost
$180.00
Cost per piece
$18.00

See the step-by-step solution ↓

Step-by-step solution

  1. Find the board feet in one piece: multiply thickness and width in inches by length in feet, then divide by 12

    1×6×812=4 BF

  2. Multiply by the number of pieces to get the total board feet

    4×10=40 BF

  3. Find the cost: total board feet times the price per board foot

    40×$4.50=$180.00

  4. One board foot is 144 cubic inches, so 12 board feet make one cubic foot

    4012=3.333333 ft³

Test yourself

20 quick questions built from this calculator's formula: work out results, predict what happens when an input changes, and work backward from an answer. Every answer comes with the working.

What this calculator does

Find out how many board feet of lumber you're buying, and what the order will cost. The board foot is the unit lumber yards use to price hardwood, and a good deal of rough and specialty softwood too. One board foot is a board 1 inch thick, 12 inches wide and 1 foot long. That's 144 cubic inches of wood.

Because a board foot measures volume, a long narrow board and a short wide one can hold exactly the same amount. Then they cost the same, too.

The calculator multiplies thickness, width and length for one piece, turns that into board feet, and multiplies by the number of pieces. You can enter the length in feet or inches. You can also work from the size the lumber is sold as, or from the smaller size it really measures. Add a price per board foot to see the cost of the whole order. Treat the numbers as estimates for planning a purchase.

Where it's used

Why this math matters outside the classroom:

  • Lumberyard pricing. Hardwood dealers price a 1 × 6 in board that is 8 ft long as 1 × 6 × 8 ÷ 12 = 4 board feet.
  • Cut lists. A furniture maker adds up the board feet for every part on a cut list before buying rough-sawn walnut.
  • Sawmill output. Small sawmill owners tally the board feet in each log they cut to know how much lumber they have to sell.
  • Comparing prices. Ten 2 × 4 in boards 8 ft long contain 53⅓ board feet, so at $1.50 a board foot they cost $80.
  • Volume in cubic inches. Students see that one board foot is a 12 × 12 × 1 in slab, or 144 cubic inches of wood.

Grade level and standards: Grade 6; Common Core State Standards for Mathematics 6.G.A.2, 6.RP.A.3.d. © Copyright 2010. National Governors Association Center for Best Practices and Council of Chief State School Officers. All rights reserved.

How to use it

  1. Choose whether to use your sizes as entered, or to turn a softwood board's labeled size into the size it really measures.
  2. Enter the thickness and width in inches, and the length in feet or inches.
  3. Enter how many identical pieces you need. If you like, add the price per board foot.
  4. Read the total board feet, the board feet in each piece and the cost.

What the inputs mean

Measure by
Lumber is usually priced on its nominal size, the size in its name. A 2×4 is billed as 2 in × 4 in, even though it measures about 1-1/2 in × 3-1/2 in once it's dried and planed smooth. That smaller, finished size is called the dressed size. Choose the dressed option to see how much wood the boards really hold. If you measured a board yourself, enter what you measured and keep the first option.
Thickness
Hardwood thickness is often given in quarters of an inch: 4/4 is 1 in, 5/4 is 1.25 in, 6/4 is 1.5 in and 8/4 is 2 in. Rough hardwood is usually priced on that rough thickness.
Width
The width the board is sold as, such as 4 for a 2×4.
Length
Switch the unit to inches for short pieces, such as the cut parts on a project list.
Price per board foot
Some yards quote a price per linear foot (per foot of length) instead. To compare, divide the price per linear foot by the board feet in one foot of that board.

Formula and method

board feet per piece = thickness (in) × width (in) × length (ft) ÷ 12
board feet per piece = thickness (in) × width (in) × length (in) ÷ 144
total board feet = board feet per piece × pieces
cost = total board feet × price per board foot

In the formulas, "in" is inches, "ft" is feet and "pieces" is how many boards you're buying. A board foot is 1 in × 12 in × 12 in = 144 in³ (cubic inches). With every measurement in inches, you divide by 144. With the length in feet, one 12 is already built in, so you divide by 12 instead. Twelve board feet make one cubic foot.

For the dressed option, the calculator uses the standard softwood sizes. Sizes under 2 in lose 1/4 in. Sizes from 2 in up to 7 in lose 1/2 in. Sizes of 8 in and over lose 3/4 in. That turns a 2×4 into 1-1/2 × 3-1/2, and a 2×10 into 1-1/2 × 9-1/4.

Worked example

You're buying ten 1×6 hardwood boards, each 8 ft long, at $4.50 per board foot, priced on the size they're sold as.

  1. Board feet per piece: 1 × 6 × 8 ÷ 12 = 4 BF.
  2. Total: 4 × 10 = 40 BF.
  3. Cost: 40 × $4.50 = $180.00.
  4. Volume check: 40 ÷ 12 = 3.333 ft³ of wood.

Result: The order is 40 board feet and costs $180.00, or $18.00 per board.

Understanding the result

The total board feet is the number a lumber yard will bill you on. The cost per piece helps when you compare a board-foot price with a price per board or per linear foot.

The dressed result tells you how much wood is really there. That matters for weight, for drying, or for working out how much material a project uses. Expect it to be noticeably lower than the labeled figure. A 2×4 holds about two thirds of the wood its name suggests.

Assumptions and limitations

  • All the pieces in one calculation are the same size. For different sizes, run each size separately and add the results.
  • The dressed sizes are the standard North American softwood sizes. Hardwood and rough-sawn lumber don't follow those rules.
  • The price is applied per board foot to the total, with no minimum charge or cutting fee.
  • Live-edge slabs and uneven boards need an average width, so the result is an estimate.
  • Waste from flaws, knots and cutting isn't included. Many woodworkers add 15 to 30 percent when buying rough hardwood for a project.
  • Prices, grading rules and the way yards round thickness and length all vary. Check your yard's own method before you order.

Frequently asked questions

How many board feet is a 2×4×8?

Using the size in its name, 2 × 4 × 8 ÷ 12 = 5.333 board feet. That's how it would be priced by the board foot. Its real dressed size, 1-1/2 × 3-1/2 in, holds 3.5 board feet of wood.

Why does lumber measure smaller than its name?

The name describes the board roughly as it was first sawn. Drying shrinks it, and planing smooths the faces and edges. So a finished 2×4 ends up about 1-1/2 by 3-1/2 inches. The trade has kept the old names out of habit.

Is a board foot the same as a linear foot?

No. A linear foot is just one foot of length, whatever the board's size. A board foot is a volume. A 1×12 has exactly one board foot per linear foot, and so does a 2×6. A 1×4 has only a third of one.

How do I count board feet for a mixed pile of lumber?

Sort the boards by size, run each group through the calculator and add the totals. For hardwood in random widths, there's a shortcut. Add up the widths of all boards with the same thickness and length, then enter that sum as the width with 1 piece.

How this calculator is checked

Method: Definition of the board foot (144 in³); standard North American softwood dressed sizes (nominal minus 1/4, 1/2 or 3/4 in). The calculation is covered by automated tests with known reference values and edge cases. Last updated 2026-10-18. Found a problem? Tell us.

Embed this calculator

Put this Board Foot Calculator on your own website or blog for free. Paste this code where you want it to appear: