Board Foot Calculator
How do I calculate board feet?
A board foot calculator converts the size and quantity of lumber into the board feet to order. Enter the thickness, width and length of each board, add a row for every size on the order, and you get the board feet per piece, the order total, the volume in cubic feet and cubic metres, and the cost if you enter a price per board foot. The calculator uses nominal dimensions, the sizes lumber is sold as, so enter 2 for a 2×4 and 6 for a 2×6, not the smaller planed sizes. That one choice is the difference between ordering the right amount and ordering nearly a third short.
Calculate board feet
Enter nominal dimensions, the sizes lumber is sold as. A 2×4 is 2 x 4 in, not 1.5 x 3.5 in.
Enter a thickness greater than 0.
Enter a width greater than 0.
Enter a length greater than 0.
Enter a quantity of 1 or more, as a whole number.
Enter a waste allowance from 0 to 50 percent.
There is no single standard allowance. Enter your own.
Enter a price of 0 or more, or leave it blank.
Leave blank for no cost.
Enter your dimensions and click Calculate.
No result yet. Enter your dimensions and click Calculate.
The calculator is a cut list. Each row takes a thickness in inches (nominal), a width in inches (nominal), a length with its own unit selector (ft, in, yd, cm, m), and a quantity. Add a row for every size on the order and remove any row you do not need. The waste allowance is a visible input, set to 10 percent by default as a starting point you can change, and there is no single standard allowance, so enter your own. Price per board foot is optional: leave it blank and no cost is shown. The formula used is shown directly under the result, so you can check the number.
What is a board foot?
One board foot is 144 cubic inches, the volume of a piece 1 inch thick, 12 inches wide and 12 inches long. It is 1/12 of a cubic foot. One cubic metre is 423.78 board feet.
The number that matters most on this page is the difference between nominal and actual dimensions. Dimensional lumber is sold by its nominal call size, but the finished board is smaller after milling and drying. A 2×4 measures 1.5 x 3.5 inches, and a 2×6 measures 1.5 x 5.5 inches. Board feet for pricing are figured from nominal dimensions, under the American Softwood Lumber Standard PS 20-10, Section 2.2, Board measure. That rule is the reason a nominal 2×6, 8 feet long, is billed at 8.0 board feet, even though its true volume, from its actual 1.5 x 5.5 inch dimensions, is only 5.5 board feet. That is a 31 percent difference. A buyer who enters actual dimensions into a nominal-based calculator under-orders by nearly a third. Only use actual dimensions when you need the true finished volume, for example for rough-sawn hardwood, which is usually measured on actual dimensions. Hardwood grading and measurement follow the NHLA Rules for the Measurement and Inspection of Hardwood and Cypress.
Hardwood thickness is often written in quarters. A 4/4 board is 1 inch thick, 5/4 is 1.25 inches, 6/4 is 1.5 inches and 8/4 is 2 inches. The quarter figure is the rough thickness at the mill, before surfacing.
How to calculate board feet
- Measure the thickness. Measure the thickness in inches, using the nominal size for softwood dimensional lumber. A 2×6 is 2 inches, not 1.5 inches.
- Measure the width. Measure the width in inches, again using the nominal size. A 2×6 is 6 inches, not 5.5 inches.
- Measure the length. Measure the length in feet. If you measured it in inches, divide by 12 first.
- Multiply and divide by 12. Board feet = thickness (in) x width (in) x length (ft) / 12. If all three dimensions are in inches, divide by 144 instead.
- Multiply by the quantity. Board feet per piece x number of pieces gives the total for that size. Add the totals for every size on the order.
- Add waste and price it. Multiply the total by 1 plus the waste allowance to get the order total, then multiply the order total by the price per board foot for the material cost.
Common lumber sizes, nominal and actual:
| Nominal size | Actual size (thickness x width) | Board feet per linear foot |
|---|---|---|
| 1×2 | 0.75 x 1.5 in | 0.17 |
| 1×4 | 0.75 x 3.5 in | 0.33 |
| 1×6 | 0.75 x 5.5 in | 0.50 |
| 1×8 | 0.75 x 7.25 in | 0.67 |
| 1×10 | 0.75 x 9.25 in | 0.83 |
| 1×12 | 0.75 x 11.25 in | 1.00 |
| 2×2 | 1.5 x 1.5 in | 0.33 |
| 2×4 | 1.5 x 3.5 in | 0.67 |
| 2×6 | 1.5 x 5.5 in | 1.00 |
| 2×8 | 1.5 x 7.25 in | 1.33 |
| 2×10 | 1.5 x 9.25 in | 1.67 |
| 2×12 | 1.5 x 11.25 in | 2.00 |
| 4×4 | 3.5 x 3.5 in | 1.33 |
| 6×6 | 5.5 x 5.5 in | 3.00 |
A 2×4 holds 4 board feet at 6 feet, 5.33 board feet at 8 feet, 6.67 board feet at 10 feet, 8 board feet at 12 feet, 9.33 board feet at 14 feet, 10.67 board feet at 16 feet, 12 board feet at 18 feet, 13.33 board feet at 20 feet, 14.67 board feet at 22 feet and 16 board feet at 24 feet.
Board foot formula and worked example
Board feet: Board feet = thickness (in) x width (in) x length (ft) / 12.
All-inches version: Board feet = thickness (in) x width (in) x length (in) / 144.
Total board feet: Board feet per piece x quantity = total board feet for that size.
Order board feet: Order board feet = total board feet x (1 + waste percent / 100).
Volume (ft3): Volume (ft3) = total board feet / 12.
Volume (m3): Volume (m3) = total board feet x 0.00235974.
Cost: Cost = order board feet x price per board foot (only if a price was entered).
Worked Example
A 2×6 board, 8 feet long, and an order of ten 1×12 boards, 10 feet long:
2 x 6 x 8 / 12 = 96 / 12 = 8 board feet
A single 2×6 board, 8 feet long, is 8 board feet.
1 x 12 x 10 / 12 = 120 / 12 = 10 board feet per board
For the order, each 1×12 board, 10 feet long, is 10 board feet per board. Ten boards give 10 x 10 = 100 board feet. The volume of that order is 100 / 12 = 8.33 cubic feet. No waste allowance is added in this arithmetic. Add your own allowance for defects, cutting loss and mistakes, and confirm the allowance with your supplier before ordering.
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Frequently asked questions
What is a board foot?
One board foot is 144 cubic inches, the volume of a piece 1 inch thick, 12 inches wide and 12 inches long. It is 1/12 of a cubic foot.
How do you calculate board feet?
Multiply thickness in inches by width in inches by length in feet, then divide by 12. For example, a 2×6 board 8 feet long is 2 x 6 x 8 / 12 = 8 board feet.
How many board feet are in a 2×4?
A 2×4 holds 0.67 board feet per foot of length, so an 8 foot 2×4 is 5.33 board feet and a 12 foot 2×4 is 8 board feet. Use nominal dimensions, the size the lumber is sold as.
Do I use nominal or actual dimensions?
Use nominal dimensions for pricing softwood dimensional lumber, under PS 20-10 Section 2.2. A 2×4 is billed as 2 x 4 inches even though it measures 1.5 x 3.5 inches after milling and drying. Only use actual dimensions when you need the true finished volume, for example for rough-sawn hardwood.
What is the difference between a board foot and a linear foot?
A board foot is a volume, 144 cubic inches. A linear foot is a length, 12 inches of board, whatever its cross-section. A 2×6 holds 1 board foot per linear foot, and a 2×12 holds 2 board feet per linear foot.
How do I price lumber by the board foot?
Multiply the total board feet by the price per board foot. Enter your price per board foot in the calculator for a total cost. No price is published on this page, because prices vary by species, grade, region and supplier.