Board Foot Calculator: Lumber Board Feet, Linear Feet and Cost
Calculate board feet for any lumber size, length and quantity, convert between board feet and linear feet, and price a lumber list at today’s $/MBF. Handles nominal sizes (2×4, 2×6, 2×10) the way lumberyards actually invoice them.
Formula: board feet = (nominal thickness in. × nominal width in. × length ft) ÷ 12. How it works and common mistakes.
Lumber list
| Description | Nominal size | Length (ft) | Pieces | Board ft each | Board ft total | Linear ft | |
|---|---|---|---|---|---|---|---|
| Totals | 0 | 0 | 0 | ||||
Quick converter
How to calculate board feet
A board foot is a volume: 144 cubic inches of wood, or a piece 1 inch thick, 12 inches wide and 12 inches long. The formula is board feet = thickness (in) × width (in) × length (ft) ÷ 12. A 2×4 that is 8 feet long is 2 × 4 × 8 ÷ 12 = 5.33 board feet. A 2×10 at 16 feet is 2 × 10 × 16 ÷ 12 = 26.67 board feet. Multiply by the piece count and you have the board feet for the line.
The detail that trips people up is nominal versus actual size. A 2×4 actually measures 1-1/2″ × 3-1/2″, but board feet are always figured on the nominal 2″ × 4″. That is the industry convention, it is how the composite lumber price ($ per thousand board feet, or MBF) is quoted, and it is how your lumberyard invoices. If you use actual dimensions you will under-count by about 34% on a 2×4 and your cost estimate will be wrong.
Board feet per linear foot: quick reference
| Nominal size | Actual size | Board ft per linear ft | Board ft per 8′ piece | Board ft per 16′ piece |
|---|---|---|---|---|
| 2×4 | 1-1/2″ × 3-1/2″ | 0.667 | 5.33 | 10.67 |
| 2×6 | 1-1/2″ × 5-1/2″ | 1.000 | 8.00 | 16.00 |
| 2×8 | 1-1/2″ × 7-1/4″ | 1.333 | 10.67 | 21.33 |
| 2×10 | 1-1/2″ × 9-1/4″ | 1.667 | 13.33 | 26.67 |
| 2×12 | 1-1/2″ × 11-1/4″ | 2.000 | 16.00 | 32.00 |
| 4×4 | 3-1/2″ × 3-1/2″ | 1.333 | 10.67 | 21.33 |
| 6×6 | 5-1/2″ × 5-1/2″ | 3.000 | 24.00 | 48.00 |
| 1×6 | 3/4″ × 5-1/2″ | 0.500 | 4.00 | 8.00 |
Board feet, linear feet and square feet: which one to use
Framing lumber is priced by the board foot (or per thousand board feet) at the mill and wholesale level, but your local yard quotes by the piece. Linear feet is what you measure on the plan (a 40′ wall needs 120 linear feet of plate). Square feet is for sheet goods: OSB and plywood are sold by the 4×8 sheet (32 sq ft) and never by the board foot. On a professional takeoff we carry all three: linear feet from the drawings, pieces by stock length for ordering, and board feet for pricing against the market.
To go from a board-foot price to a piece price: a 2x4x8 is 5.33 board feet, so at $516 per MBF the mill-level cost is 5.33 × 0.516 = $2.75 per stud before the yard’s margin and freight. That is why a stud that is “$3.20 at the yard” tracks the composite price closely, and why the weekly framing lumber price matters to your bid.
Common mistakes
Using actual dimensions instead of nominal (under-counts by 25–35%). Forgetting to multiply by the piece count. Mixing inches and feet in the length term (length must be in feet). Applying board feet to plywood or OSB, which are sold by the sheet. And ordering by board feet alone without a piece list, which leaves the yard to guess at lengths and sends you a pile you have to cut down. Our framing calculator builds the piece list and the board feet together.
More free lumber calculators: Framing calculator · Plywood & OSB calculator · Lumber weight calculator · all calculators
Frequently asked questions
How many board feet in a 2x4x8?
5.33 board feet: 2 × 4 × 8 ÷ 12. A 2x4x10 is 6.67, a 2x4x12 is 8, and a 2x4x16 is 10.67 board feet.
How many board feet in a 2x6x8?
8 board feet: 2 × 6 × 8 ÷ 12. A 2×6 is exactly 1 board foot per linear foot, which makes it the easiest size to figure in your head.
Do I use nominal or actual dimensions to calculate board feet?
Nominal. Board feet are always figured on the nominal size (2×4 = 2″ × 4″) for dimensional lumber. Actual dimensions are only used for rough-sawn hardwood, which is sold by measured thickness in quarters (4/4, 8/4).
How many board feet in a thousand board feet (MBF)?
1,000. Lumber market prices are quoted per MBF. A framing package for a 2,000 sq ft house is typically 14,000–16,000 board feet of dimensional lumber, so at $516/MBF the raw lumber is roughly $7,200–$8,300 before sheathing, engineered lumber and hardware.
How do I convert board feet to linear feet?
Divide board feet by the board feet per linear foot for that size. 1,000 board feet of 2×4 is 1,000 ÷ 0.667 = 1,500 linear feet, or about 94 pieces at 16′. Use the quick converter above.
How many board feet do I need to frame a house?
Roughly 6–8 board feet of dimensional lumber per square foot of floor area for a typical single-family house, before sheathing and engineered lumber. A 2,000 sq ft house lands around 14,000–16,000 board feet. See how much lumber to frame a house for the breakdown by component.