Woodworking Reference
Board Foot Calculator
Calculate board feet, add a waste allowance, and estimate lumber cost. One board foot is a piece 1 inch thick, 12 inches wide, and 12 inches long: 144 cubic inches.
- Formula preview on every result
- Feet plus inches supported
- Fractions accepted, like 8 1/4
- Cost and waste included
Your boards
Lumber is charged at rough nominal size, before surfacing.Waste covers cuts, defects, and planing. 10% suits most furniture projects.
Enter your first board above.
The Basics
What one board foot means
One board foot is 144 cubic inches of lumber. The formula is simple:
Board feet = thickness (in) × width (in) × length (in) ÷ 144
Or, with length in feet: thickness × width × length (ft) ÷ 12. Yards charge at the rough nominal size, before surfacing, so measure thickness and width before planing if you want your total to match theirs.
The anatomy of a board foot: a worked example
You buy 4 rough-sawn White Oak planks, each 8/4 (2 inches) thick, 7 inches wide, and 96 inches long, and you allow 15% waste:
- One plank: 2 × 7 × 96 ÷ 144 = 9.333 board feet
- 4 planks: 37.33 board feet
- With 15% waste: 37.33 × 1.15 = 42.93 board feet to order
Try it above: enter 8/4, 7 inches, 8 feet, quantity 4, and 15% waste, and you will get the same numbers.
Quick Reference
Common board foot chart
Board feet for one 8-foot board at common sizes. The full chart page follows; use the calculator above for any other size.
| Board size | Board feet (8 ft) |
|---|---|
| 1 × 6 | 4.00 |
| 1 × 8 | 5.33 |
| 2 × 4 | 5.33 |
| 2 × 6 | 8.00 |
| 2 × 8 | 10.67 |
| 2 × 10 | 13.33 |
| 2 × 12 | 16.00 |
Each value is thickness (in) × width (in) × 96 (in) ÷ 144. Values rounded to two decimals.
Guides
Supporting guides
How to calculate board feet
Step by step, with worked examples, common mistakes, and the inches-versus-feet trap.
Coming soonWhat is a board foot?
The definition, the 144 cubic inch rule, and why lumber is sold this way.
Coming soonLog board foot calculator
Doyle, Scribner, and International log rules, from small-end diameter and length.
Coming soonNominal vs actual lumber sizes
Why a nominal 1-inch board measures 3/4 inch, and the 4/4 to 12/4 thickness scale.
Coming soonBoard foot vs linear foot
When each unit applies, and how to convert between them without overbuying.
Coming soonLumber cost calculator
From price per board foot to project total, with waste and per-piece costs.
Coming soonQuestions
Frequently asked questions
What is a board foot?
One board foot is a piece of lumber 1 inch thick, 12 inches wide, and 12 inches long, which equals 144 cubic inches.
How do you calculate board feet?
Multiply thickness in inches by width in inches by length in feet, then divide by 12. If you measure length in inches instead, divide by 144.
What does 4/4 mean in lumber?
4/4 means four quarters of an inch, or 1 inch, in rough nominal thickness. 5/4 is 1.25 inches, 6/4 is 1.5 inches, and 8/4 is 2 inches.
Why is a nominal 1-inch board actually 3/4 inch?
Boards are measured and charged at their rough nominal size before surfacing. Surfacing (planing) removes material, so a nominal 1-inch board measures about 3/4 inch thick after surfacing, but it is still sold as 1 inch.
How much waste should I add?
A common allowance is 10 percent for cuts, defects, and planing. Use 5 percent for simple straight cuts and 15 to 20 percent for complex projects or rough lumber.
Why does the lumber yard's total differ from mine?
Yards measure rough nominal size, not the surfaced size you measure at home, and they round each board. Measure before surfacing and allow for waste to match their total.