What Is a Board Foot?
A board foot is the standard unit of volume used to price lumber, especially hardwoods, in the United States and Canada. One board foot equals 144 cubic inches of wood, which you can visualize as a piece measuring 12 inches long × 12 inches wide × 1 inch thick, or any equivalent volume. A 6 ft long 1×6 board, for instance, also contains exactly 3 board feet.
The board foot system originated when most lumber was sold rough — that is, milled to approximate dimensions but not surfaced flat. Buying by volume rather than by piece allowed prices to scale with the actual amount of wood, regardless of the variable widths and lengths typical of rough hardwood. Today, dimensional softwood (2×4s, 2×6s) is generally sold by linear foot or per piece, while rough hardwood is still sold by board foot.
How to Calculate Board Feet
The formula is simple, but the trick is keeping your units consistent. All three dimensions must be in inches, or you can use feet for length if you remember to divide by 12 instead of 144:
OR
Board feet = (Thickness × Width × Length in feet) ÷ 12
Worked example
Say you're buying 10 pieces of red oak that are 1 inch thick, 6 inches wide, and 8 feet long:
- BF per piece: (1 × 6 × 8) ÷ 12 = 4 board feet
- Total BF: 4 × 10 = 40 board feet
- Cost (at $6.50/BF for red oak): 40 × $6.50 = $260
- With 10% waste: Order 44 BF = $286
Board Feet by Project Type
Different projects have radically different lumber requirements. Here are typical board foot quantities for common woodworking and construction jobs.
Decks
A 12 × 16 ft deck (192 sq ft of decking surface) using 5/4 × 6 boards needs approximately 240 board feet for the deck surface alone. Adding framing — joists (2×8s at 16" on center), beams, posts, and railing — brings the total to roughly 400–500 board feet of pressure-treated softwood. Premium decking (mahogany, ipe, cedar) is sold by BF and costs significantly more per square foot.
Fences
A 100 linear feet of 6 ft tall privacy fence requires approximately: 110 BF of pressure-treated posts (4×4 × 8 ft, every 8 ft), 67 BF of horizontal rails (2×4 × 100 ft total), and 240 BF of 1×6 vertical pickets. Total around 420 BF for materials. Add 10–15% for cuts and replacements.
Kitchen cabinets (face frames and doors)
A 10-foot run of cabinets typically requires 200–300 board feet of solid hardwood for face frames, doors, and drawer fronts, plus 4–6 sheets of plywood for the boxes themselves. Add 15% waste because of the complex joinery and door-and-rail construction. Material cost for mid-range hardwoods (cherry, maple) runs $1,500–$3,000.
Hardwood flooring
A 300 sq ft room with 3/4 inch × 3-1/4 inch tongue-and-groove hardwood needs approximately 61 board feet for the flooring itself, plus 10% waste = 67 BF. At $7/BF for red oak, that's about $470 in flooring. Wide-plank or engineered flooring sold by square foot is priced differently.
Custom furniture
A solid wood dining table (36" × 72") with substantial top and legs requires roughly 30–40 board feet of 8/4 stock (8/4 means 2 inches thick). A bookshelf unit (84" tall × 36" wide) needs around 50–70 board feet. These figures assume mostly straight cuts; intricate work with curved pieces can double the requirement.
Garage and shed framing
A 12 × 12 ft shed with conventional stick framing needs about 650–800 board feet of dimensional softwood (2×4 studs, 2×6 plates, 2×6 rafters), plus plywood sheathing. Detached garage at 24 × 24 ft: roughly 2,000–2,500 BF of framing lumber.
Hardwood vs Softwood: Different Math
Softwood (pine, fir, spruce) used in construction is typically sold per piece or per linear foot, in standard nominal sizes. The lumberyard price already accounts for the volume in board feet — you don't usually need to calculate it unless you're estimating total project cost.
Hardwood (oak, maple, walnut, cherry) is almost always sold by the board foot, often in random widths and lengths. You'll see prices like "$6.50/BF for FAS red oak, 4/4 thick" and you need to calculate exactly how many board feet you're getting from a stack of mixed boards.
| Species | Grade FAS ($/BF) | Common ($/BF) | Notes |
|---|---|---|---|
| Poplar | $3–5 | $2–3.50 | Beginner-friendly, paint-grade |
| Red oak | $5–8 | $4–6 | Most popular hardwood in US |
| White oak | $6–10 | $5–7 | Durable, used in flooring & furniture |
| Hard maple | $6–9 | $5–7 | Cabinets, butcher blocks |
| Cherry | $7–11 | $5–8 | Premium furniture wood |
| Walnut | $10–16 | $8–12 | Dark, expensive, beautiful |
| Mahogany | $12–20 | $9–14 | Boat building, fine furniture |
| Sapele | $8–13 | $6–10 | Mahogany alternative |
Understanding Lumber Dimensions: Nominal vs Actual
This trips up almost everyone the first time they buy lumber. The size on the label isn't the size of the wood you take home. A "2×4" is actually 1-1/2 × 3-1/2 inches. The difference comes from the planing process that smooths rough lumber into the dimensional product you buy.
| Nominal | Actual (S4S) | Nominal BF/LF | Actual BF/LF |
|---|---|---|---|
| 1 × 2 | 3/4 × 1-1/2 | 0.17 | 0.094 |
| 1 × 4 | 3/4 × 3-1/2 | 0.33 | 0.22 |
| 1 × 6 | 3/4 × 5-1/2 | 0.50 | 0.34 |
| 1 × 8 | 3/4 × 7-1/4 | 0.67 | 0.45 |
| 2 × 4 | 1-1/2 × 3-1/2 | 0.67 | 0.44 |
| 2 × 6 | 1-1/2 × 5-1/2 | 1.00 | 0.69 |
| 2 × 8 | 1-1/2 × 7-1/4 | 1.33 | 0.91 |
| 2 × 10 | 1-1/2 × 9-1/4 | 1.67 | 1.16 |
| 2 × 12 | 1-1/2 × 11-1/4 | 2.00 | 1.41 |
For pricing purposes, most lumberyards use nominal dimensions. For estimating actual wood you'll have to work with — especially in fine woodworking — use actual dimensions. Our calculator handles both: enter the dimensions you want to compute with, and it returns the matching board feet.
Hardwood Grades: What They Mean
Hardwood is graded by the National Hardwood Lumber Association (NHLA) based on the percentage of clear, defect-free face. Higher grades cost more but waste less.
- FAS (First and Seconds): The premium grade. Minimum 83% clear face, both sides. Used for fine furniture, cabinets, and millwork.
- Selects: Minimum 83% clear on one face, FAS on the other. Slightly cheaper than FAS and works for most furniture.
- #1 Common: Minimum 66% clear face. Great value for paint-grade work or projects with shorter required clear cuttings.
- #2 Common: Minimum 50% clear. Lots of knots and defects; suitable for rustic projects, framing, or shop fixtures.
- #3 Common: Rough lumber with significant defects. Used for pallets, crates, and concealed structural work.
Waste Factor for Woodworking
Unlike construction lumber where you can usually find a use for shorter pieces, fine woodworking generates significant waste. Defects must be cut around. Long pieces need to be ripped from wider boards. Joinery (mortises, dovetails, etc.) consumes material. Build these realistic waste factors into your estimate:
- 10% waste: Straight, simple work in defect-free FAS lumber — shelving, simple cabinet boxes, decking.
- 15% waste: Cabinet work with face frames, doors, and drawer fronts. Most furniture projects.
- 20% waste: Highly figured wood (curly maple, burled walnut) where matching grain matters. Rough lumber with knots.
- 25–30% waste: Curved work, bent laminations, intricate joinery, or when working with very short required cuts from longer boards.
Where to Buy Lumber and How to Save
Big-box stores (Home Depot, Lowe's) are convenient for dimensional softwood and basic hardwoods like poplar, red oak, and pine — but selection is limited and quality varies. For serious woodworking, you want a dedicated hardwood dealer. Here's how to source intelligently:
- Local hardwood dealers: Best price-to-quality ratio for hardwoods. Many will let you pick boards individually. Online directories list dealers by region.
- Mill direct: If you have a local sawmill, buying rough lumber and milling it yourself saves 30–50%. Requires a jointer and planer plus the skill to use them.
- Online specialty suppliers: Bell Forest Products, Cook Woods, and others ship anywhere. Premium for exotic species you can't get locally.
- Reclaimed and salvage: Local Habitat for Humanity ReStores, demolition contractors, and Craigslist often have old lumber at fraction of new prices.
For bulk orders, always ask about volume discounts. Most hardwood dealers give 5–10% off for orders over 100 BF, and 10–15% off for orders over 500 BF. Negotiate.
Tools for Working with Lumber
To efficiently use the lumber you've calculated, you'll need a few key tools. Tape measure and combination square cover most measuring needs. A circular saw or miter saw handles crosscuts; a table saw is essential for ripping. For hardwoods sold rough, a jointer and planer let you mill your own — saving substantial money on surfaced lumber. A digital moisture meter ($30–80) prevents the disaster of building with wood that's too wet, which causes shrinkage cracks and joint failures within months.