Enter the thickness in inches, the width in inches, the length in feet and the number of boards. A board foot is a volume of lumber equal to 144 cubic inches, a piece 1 inch thick, 12 inches wide and 1 foot long. Hardwood lumber is priced by the board foot.
Use the rough or nominal dimensions the seller uses, and remember that surfacing removes material, so a board nominally 1 inch thick is often planed to three quarters of an inch.
A board foot is 144 cubic inches. Confirm how the seller measures thickness and width, and compare that pricing basis with the actual finished dimensions needed by the cut list. Milling losses and defects depend on the stock; there is no fixed waste percentage for every project.
Board feet per board from thickness
| Thickness | 1 |
|---|---|
| Width | 6 |
| Length | 8 |
| Number of boards | 10 |
| Board feet per board | 4 |
| Total board feet | 40 |
Common error: Using the nominal width as the true width. A 2 by 8 is really 1.5 by 7.25 inches once surfaced, but lumber yards often quote the nominal figure for board feet.
Board Feet: formula
Board Feet: changing Thickness
| Thickness | Board feet per board | Total board feet |
|---|---|---|
| 0.8 | 3.2 | 32 |
| 0.9 | 3.6 | 36 |
| 1 (example) | 4 | 40 |
| 1.1 | 4.4 | 44 |
| 1.2 | 4.8 | 48 |
Board Feet: compare input ranges
| Input | Tested from | To | Board feet per board: low input | Board feet per board: high input | Swing |
|---|---|---|---|---|---|
| Length | 7 | 9 | 3.5 | 4.5 | 1 (25%) |
| Thickness | 0.9 | 1.1 | 3.6 | 4.4 | 0.8 (20%) |
| Width | 5.4 | 6.6 | 3.6 | 4.4 | 0.8 (20%) |
| Number of boards | 9 | 11 | 4 | 4 | 0 |
Board Feet: individual input comparisons
| Input | Value | Board feet per board | Total board feet |
|---|---|---|---|
| Thickness | 0.8 | 3.2 | 32 |
| 0.9 | 3.6 | 36 | |
| 1 | 4 | 40 | |
| 1.1 | 4.4 | 44 | |
| 1.2 | 4.8 | 48 | |
| Width | 4.8 | 3.2 | 32 |
| 5.4 | 3.6 | 36 | |
| 6 | 4 | 40 | |
| 6.6 | 4.4 | 44 | |
| 7.2 | 4.8 | 48 | |
| Length | 6 | 3 | 30 |
| 7 | 3.5 | 35 | |
| 8 | 4 | 40 | |
| 9 | 4.5 | 45 | |
| 10 | 5 | 50 | |
| Number of boards | 8 | 4 | 32 |
| 9 | 4 | 36 | |
| 10 | 4 | 40 | |
| 11 | 4 | 44 | |
| 12 | 4 | 48 |
Board feet per board: Thickness against Width
| Thickness / Width | 4.8 | 6 | 7.2 |
|---|---|---|---|
| 0.8 | 2.6 | 3.2 | 3.8 |
| 0.9 | 2.9 | 3.6 | 4.3 |
| 1 | 3.2 | 4 | 4.8 |
| 1.1 | 3.5 | 4.4 | 5.3 |
| 1.2 | 3.8 | 4.8 | 5.8 |
Board Feet: values and definitions
| Quantity and definition | Value used |
|---|---|
| Thickness — Board thickness, in inches. | 1 |
| Width — Board width, in inches. | 6 |
| Length — Board length, in feet. | 8 |
| Number of boards — Number of boards of this size. | 10 |
| Board feet per board | 4 |
| Total board feet | 40 |
Length: half and double
| Length | Board feet per board |
|---|---|
| 4 | 2 |
| 8 | 4 |
| 16 | 8 |
A board foot is a volume of wood, 144 cubic inches, and hardwood is sold by it. A board 1 inch thick, 6 inches wide and 8 feet long is 4 board feet, and ten of them are 40. Thicker and wider boards multiply quickly, so a 2 by 8 that is 8 feet long is 10.7 board feet.
The price per board foot varies by species and grade, and the nominal thickness is often quoted in quarters of an inch.
Confirm whether the price is per board foot of rough or surfaced lumber, and allow for the waste when you cut around defects.
Plan cutting on the cut list and sheet nesting calculator, framing on the deck material and joist span pages and volumes on the rectangular prism calculator. The unit price comparison and cubic feet pages help compare suppliers, and the stair and rafter calculators give lengths.
How do I calculate board feet?
Multiply thickness in inches by width in inches by length in feet and divide by 12.
Why is my finished board thinner than the thickness I paid for?
Lumber is sold by its rough or nominal thickness, and the planing and sanding that finish it remove about a quarter inch of material.