Square Feet to Board Feet Calculator
Convert between square feet, linear feet and board feet for softwood and hardwood sizes, with board counts and price per board foot.
Built by Toolsque Team · last updated October 14, 2026 · checked against our testing process
How to convert square feet, linear feet and board feet
- Pick the lumber size: a softwood size such as 2x6, a hardwood thickness such as 5/4, or type the thickness and width.
- Type into any one box: square feet, linear feet or board feet. The other two fill in.
- Set the board length to see how many boards that is, rounded up.
- Add the price per board foot if you have one, for the total and the price per linear and square foot.
- Check the formula line under the result to see the exact math used.
Square feet to board feet: multiply, do not divide
A board foot is a piece of wood 12 inches long, 12 inches wide and 1 inch thick: 144 cubic inches. So one square foot of 1 inch thick board is exactly one board foot, and the conversion is a single multiplication:
Board feet = square feet × thickness in inches
200 square feet of 1 inch boards is 200 board feet. The same area in 2 inch stock is 400 board feet, and in 3/4 inch stock it is 150. Many square feet to board feet converters online divide by 12 as well, which gives 16.7 for the first example. That is twelve times too small, and it is the most common error in this conversion. The 12 belongs in the formula for linear feet, below, not in the one for square feet.
Going the other way, square feet = board feet ÷ thickness in inches. 300 board feet of 5/4 hardwood (1.25 inches) covers 240 square feet of face area.
Board feet to linear feet, and back
Linear feet need the width as well as the thickness:
- Board feet = thickness (in) × width (in) × length (ft) ÷ 12
- Linear feet = board feet × 12 ÷ (thickness × width)
A 2x6 is 2 × 6 ÷ 12 = 1 board foot for every linear foot, which is why 2x6 is the easy one to remember. This table gives the factor for the common sizes, so you can convert in your head:
| Lumber | Board feet per linear foot | Linear feet per board foot |
|---|---|---|
| 1x4 | 0.333 | 3 |
| 1x6 | 0.5 | 2 |
| 1x8 | 0.667 | 1.5 |
| 2x4 | 0.667 | 1.5 |
| 2x6 | 1 | 1 |
| 2x8 | 1.333 | 0.75 |
| 2x10 | 1.667 | 0.6 |
| 2x12 | 2 | 0.5 |
| 4x4 | 1.333 | 0.75 |
| 6x6 | 3 | 0.333 |
So 120 linear feet of 2x4 is 80 board feet, and 50 board feet of 1x6 is 100 linear feet.
Nominal or actual size: which numbers to use
Softwood framing lumber is counted at its nominal size. A 2x6 actually measures about 1.5 by 5.5 inches once it is dried and planed, but it is still billed as 2 by 6. Use the nominal numbers, which is what the softwood buttons above do.
Hardwood is sold by thickness in quarters of an inch, measured rough, before planing: 4/4 is 1 inch, 5/4 is 1.25, 6/4 is 1.5 and 8/4 is 2. A board sold as 4/4 and planed smooth ends up nearer 13/16 of an inch, but it is still priced as 4/4. Widths and lengths of hardwood are random, so a lumberyard measures each board and adds up the board feet.
Price per board foot, linear foot and square foot
Hardwood is usually priced per board foot, while home centers price boards per piece or per linear foot. Enter the price per board foot above and the calculator gives the cost per linear foot for the size you chose, and the cost per square foot of face area. For example, walnut at $12 a board foot in 8/4 by 6 inches is $12 a linear foot and $24 a square foot, and an 8 foot board costs $96.
Buy more than the finished project needs. Knots, checks, sapwood and cutting losses mean woodworkers commonly add 20 to 30 percent to the board feet in a cut list.
Board feet in a log
A standing tree or a log is measured with a log scale instead, which estimates how much sawn lumber it will yield after the saw kerf and slabs are lost. The Doyle scale, common in the eastern US, uses board feet = (small end diameter in inches − 4)² × length in feet ÷ 16. A 16 inch log 12 feet long works out to 108 board feet. Doyle underestimates small logs, so sawmills in other regions use the Scribner or International 1/4 inch scales, which give higher figures for the same log.
Related construction calculators
If the lumber is for a floor or deck frame, the joist span calculator checks how far each size can span, and the construction cost estimator rolls lumber into a full project budget.
Frequently Asked Questions
How do I convert square feet to board feet?
Multiply the square feet by the thickness in inches. 100 square feet of 1 inch lumber is 100 board feet, and 100 square feet of 2 inch lumber is 200 board feet.
How many board feet are in a 2x4?
Two thirds of a board foot per linear foot, using the nominal 2 by 4 inches. An 8 foot 2x4 is 5.33 board feet and a 12 foot 2x4 is 8.
How do I convert board feet to linear feet?
Multiply the board feet by 12, then divide by the thickness times the width in inches. 60 board feet of 1x4 is 60 x 12 / 4 = 180 linear feet.
Is a board foot the same as a square foot?
Only for 1 inch thick material. A board foot is a volume (144 cubic inches) and a square foot is an area, so thicker wood has more board feet per square foot.
Should I use the nominal or the actual size?
Use nominal sizes for softwood framing lumber and rough thickness in quarters for hardwood, because that is how both are priced.
How do I calculate board feet for a whole cut list?
Work out each part in thickness x width x length in feet / 12, add them up, then add 20 to 30 percent for defects and cutting waste.