How to use the board foot calculator
Hardwood, timber framing stock and a lot of rough-sawn softwood are bought by the board foot, a unit of volume rather than length. That makes it hard to compare a pile of boards of different sizes, or to turn a cut list from a drawing into an order. This calculator does it line by line.
- Enter each board size as nominal thickness and width in inches, with its length and the number you need. Use 1 for 4/4 stock, 1.25 for 5/4, 2 for 8/4 and so on. For dimensional lumber, enter the nominal size: 2 and 6 for a 2x6.
- Add as many lines as your cut list needs with the add button, and choose whether lengths are in feet or inches.
- Set a waste allowance and your price per board foot to get the quantity to order and an estimated cost.
The results show net board feet, board feet with waste, the cost, the volume in cubic feet and cubic metres, and the total linear feet across all lines.
Board foot formulas
Board feet = Thickness (in) × Width (in) × Length (ft) ÷ 12
Board feet = Thickness (in) × Width (in) × Length (in) ÷ 144
1 board foot = 144 in³ = 0.002360 m³ · 1 m³ = 423.8 board feet
Order quantity = Board feet × (1 + Waste % ÷ 100)
Because a board foot is 1 inch × 12 inches × 1 foot, a 1x12 has exactly one board foot in every foot of length. That's a handy check: a 1x6 has half a board foot per foot, a 2x6 has one, and a 2x12 has two.
| Nominal size | Board ft per linear ft | Board ft in an 8 ft piece | Board ft in a 12 ft piece |
|---|---|---|---|
| 1x6 | 0.50 | 4.00 | 6.00 |
| 2x4 | 0.67 | 5.33 | 8.00 |
| 2x6 | 1.00 | 8.00 | 12.00 |
| 2x10 | 1.67 | 13.33 | 20.00 |
| 4x4 | 1.33 | 10.67 | 16.00 |
| 6x6 | 3.00 | 24.00 | 36.00 |
Worked examples
A walnut dining table
The top needs six boards of 8/4 walnut, 7 inches wide and 8 feet long: 2 × 7 × 8 ÷ 12 = 9.33 board feet each, 56 in total. The base adds four 8/4 legs, 4 inches wide and 30 inches long: 2 × 4 × 30 ÷ 144 = 1.67 each, 6.67 in total. With 25% waste, order about 78 board feet. At $14 per board foot, that's roughly $1,100.
Framing a deck
Twelve 2x8 joists at 12 feet are 2 × 8 × 12 ÷ 12 = 16 board feet each, 192 in total, and two 2x10 rim boards at 16 feet add 26.67 each. That's 245 board feet, or about 0.58 m³, before waste.
Converting a metric timber order
A supplier quotes oak at a price per cubic metre. Your cut list comes to 120 board feet, which is 120 × 0.00236 = 0.28 m³. If the supplier measures actual planed sizes, the figure will be a little lower, so ask which basis they use.
Who this calculator helps
- Architects and interior designers specifying timber joinery, cladding, screens and furniture and checking budget quantities.
- Woodworkers and cabinetmakers turning a cut list into a hardwood order.
- Builders and framers pricing timber frames, decks and structural members sold by volume.
- Quantity surveyors and estimators converting between board feet and cubic metres.
- Students learning how timber is measured and priced in North America.
Tips for ordering lumber
- Round each piece up to the lengths the yard stocks, usually 2 ft increments, before you count board feet.
- Rough hardwood loses about 3/16 inch in thickness when surfaced, so buy one quarter thicker than your finished dimension if it has to finish at a full inch.
- Group the cut list by species and thickness. Prices per board foot change a lot between 4/4 and 8/4 of the same wood.
- For sheet goods and studs in walls, the drywall calculator and square footage calculator are a quicker route to quantities.
- Converting site measurements? The feet and inches converter handles fractions and metric.
Planning a timber-heavy interior? See how oak, walnut or ash finishes look in the actual room with Room Redesign.
