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Lumber Calculator
Calculate board feet, stud count for a framed wall, or total linear footage cost. Uses the (thickness x width x length) / 12 board-foot formula and 16 or 24 in OC framing.
Lumber order
Add a row for each lumber size. Nominal dimensions (a 2x4 stays 2 and 4). Board feet use the formula (thickness in x width in x length ft) / 12.
Total board feet
53.33 BF
- Total linear feet
- 80 ft
- Total board feet
- 53.33 BF
- Total pieces
- 10
- Recommended extra (waste)
- 10%
Frequently Asked Questions about the Lumber Calculator
How do I calculate board feet?
Board feet equal (thickness in inches x width in inches x length in feet) divided by 12. A 2x4x8 works out to (2 x 4 x 8) / 12 = 5.33 BF. Multiply by quantity for an order: 10 of those studs total 53.33 BF. Use nominal dimensions (a 2x4 stays 2 and 4) because that is how lumberyards price the stock.
How many studs do I need for a wall?
Divide the wall length in inches by the on-center spacing, then add 1 for the end stud. An 8 ft wall at 16 in OC needs (8 x 12) / 16 + 1 = 7 studs. At 24 in OC the same wall needs 5 studs. The calculator rounds up so partial bays still get a stud, which is what framers do in practice.
Should I frame walls at 16 in or 24 in on center?
16 in OC is the default for interior and most exterior walls in US residential framing. 24 in OC (often called advanced framing or OVE) saves about a third of the lumber and improves insulation, but requires 2x6 studs, aligned floor and roof framing above, and code-approved sheathing. Stick with 16 in for retrofit work unless your plans specifically call for 24.
How much waste should I add to a lumber order?
Plan for about 10 percent extra for cuts, end-trims, knots, splits, and the occasional warped board the yard will not exchange. The calculator surfaces that 10 percent as a recommended extra but does not pad the totals, so you can add it manually if your project is straightforward or bump it to 15 percent for complex layouts with many short cuts.
What is the difference between nominal and actual lumber sizes?
A 2x4 is actually 1.5 x 3.5 in after drying and surfacing at the mill. Lumberyards price by the nominal size, so board feet are calculated nominally (2 x 4) even though the wood you receive is smaller. Use actual dimensions only when laying out fits in tight spaces or detailing joinery.