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Board Foot Calculator Guide
A board foot is the standard unit of lumber volume in North America, used by lumber yards, sawmills, and woodworkers to price and estimate hardwood and specialty lumber. If you're buying oak flooring, planning a deck, or quoting a cabinet job, board feet is the number that matters. Our calculator handles the math instantly — including total cost when you enter your lumber price.
Board Feet = (Thickness" × Width" × Length') ÷ 12
Thickness and width are in inches, length is in feet. One board foot = 144 cubic inches of wood.
The formula is simple, but there's one catch that trips up most people: you need to use the actual dimensions of the board, not the nominal dimensions. A "2×4" actually measures 1.5" × 3.5" — two numbers that produce very different board foot results. The calculator above uses whichever number you type in, so always double-check which dimension system your lumber yard quotes in before entering prices.
How to Calculate Board Feet Step by Step
Working through the formula manually takes four steps. Take a single piece of 1-inch thick, 8-inch wide, 10-foot long cherry board:
Multiply thickness by width: 1" × 8" = 8. Multiply that by length in feet: 8 × 10 = 80. Divide by 12: 80 ÷ 12 = 6.67 board feet. If the board costs $6 per board foot, the total is 6.67 × $6 = $40.02.
When buying multiple boards of the same size, multiply the per-piece result by quantity. For 15 boards of the same cherry: 6.67 × 15 = 100 board feet total.
Nominal vs. Actual Lumber Dimensions — What to Use
This is the single most confusing part of board foot calculations. Lumber is sold under nominal names but delivered at smaller actual dimensions after drying and planing. Here's how the most common sizes compare:
| Nominal Size | Actual Size | BF per Foot (nominal) | BF per Foot (actual) |
|---|---|---|---|
| 1×4 | ¾" × 3½" | 0.33 bf/ft | 0.22 bf/ft |
| 1×6 | ¾" × 5½" | 0.50 bf/ft | 0.34 bf/ft |
| 1×8 | ¾" × 7¼" | 0.67 bf/ft | 0.45 bf/ft |
| 1×12 | ¾" × 11¼" | 1.00 bf/ft | 0.70 bf/ft |
| 2×4 | 1½" × 3½" | 0.67 bf/ft | 0.44 bf/ft |
| 2×6 | 1½" × 5½" | 1.00 bf/ft | 0.69 bf/ft |
| 2×8 | 1½" × 7¼" | 1.33 bf/ft | 0.91 bf/ft |
| 2×10 | 1½" × 9¼" | 1.67 bf/ft | 1.16 bf/ft |
| 2×12 | 1½" × 11¼" | 2.00 bf/ft | 1.41 bf/ft |
| 4×4 | 3½" × 3½" | 1.33 bf/ft | 1.02 bf/ft |
Hardwood lumber from a sawmill or specialty dealer is almost always sold by actual dimensions. Dimensional construction lumber from a home improvement store is typically priced by linear foot using nominal naming, not board feet. When buying hardwood, always confirm which system applies before calculating your cost.
Lumber Price per Board Foot — Reference Guide
Prices vary significantly by species, grade, region, and whether the lumber is rough-sawn, S2S (surfaced two sides), or S4S (surfaced four sides). The table below shows typical ranges as a starting reference — always get a current quote from your supplier before finalizing a project budget.
| Wood Species | Category | Price Range (per BF) | Common Uses |
|---|---|---|---|
| Pine (common) | Softwood | $0.50–$1.50 | Framing, shelving, trim |
| Cedar | Softwood | $2.00–$5.00 | Decking, siding, closets |
| Douglas Fir | Softwood | $1.50–$3.50 | Structural framing, beams |
| Poplar | Hardwood | $2.00–$4.00 | Painted furniture, cabinets |
| Red Oak | Hardwood | $3.50–$7.00 | Flooring, furniture, cabinets |
| Hard Maple | Hardwood | $4.00–$8.00 | Butcher blocks, flooring, cutting boards |
| Cherry | Hardwood | $5.00–$10.00 | Fine furniture, cabinetry |
| Walnut | Hardwood | $8.00–$18.00 | Premium furniture, gunstocks |
| White Oak | Hardwood | $5.00–$12.00 | Boat building, whiskey barrels, furniture |
| Teak | Exotic | $20.00–$45.00 | Marine, outdoor furniture |
| Mahogany | Exotic | $10.00–$25.00 | Boat trim, musical instruments |
Worked Example — Dining Table Top
Project: Walnut dining table top, 36" wide × 84" long × 1½" thick, 5 boards
Per board: (1.5" × 7.2" × 7') ÷ 12 = 6.3 board feet
Total board feet: 6.3 × 5 boards = 31.5 board feet
Add 15% waste for glue-up and surfacing: 31.5 × 1.15 = 36.2 board feet to order
Cost at $12/BF: 36.2 × $12 = $434.40
Board Feet vs. Linear Feet — Which to Use
The unit you use depends on the type of lumber and what you're buying it for. Board feet measure volume and are used for hardwood lumber, rough-sawn timber, specialty species, and any situation where thickness varies. Linear feet measure only length and are used for dimensional framing lumber (2×4, 2×6), decking, trim, and molding where the cross-section is fixed.
If your lumber yard quotes hardwood in board feet and you need to compare it to a competitor quoting by the linear foot, multiply the linear foot price by the board feet per linear foot to get an equivalent price. For a 4/4 (1" thick) × 6" wide board: 1 linear foot = (1 × 6 × 1) ÷ 12 = 0.5 board feet. So a price of $2.50/linear foot equals $5.00/board foot.
Waste Allowances — How Much Extra to Order
Always order more lumber than your calculation says you need. The right waste percentage depends on what you're building:
- Simple straight cuts (framing, shelving): Add 5–10%
- Furniture with multiple parts: Add 10–15%
- Panels with glue-ups: Add 15–20% (for surfacing after gluing)
- Figured or highly figured wood: Add 15–25% (for defect culling)
- Irregular live-edge boards: Add 20–30% (uneven edges reduce yield)
- Flooring: Add 10–15% for standard rooms, 15–20% for diagonal layouts
4/4, 5/4, 8/4 — Understanding Hardwood Lumber Thickness Designations
Hardwood lumber is sold in thickness measured in quarters of an inch. "4/4" (read "four-quarter") means 4/4" = 1 inch rough thickness. After surfacing and planing, you get slightly less. Here are the common thicknesses and their finished dimensions:
| Designation | Rough Thickness | Typical Finished | Common Uses |
|---|---|---|---|
| 4/4 | 1" | ¾" | Cabinet doors, furniture panels |
| 5/4 | 1¼" | 1" | Decking, table tops, thick panels |
| 6/4 | 1½" | 1¼" | Heavier furniture parts, legs |
| 8/4 | 2" | 1¾" | Turning blanks, thick table tops |
| 10/4 | 2½" | 2¼" | Large turnings, sculpted pieces |
| 12/4 | 3" | 2¾" | Mantelpieces, heavy furniture legs |
When calculating board feet for rough hardwood, use the rough thickness (the designation). The lumber yard prices on the rough dimension. When planning your project's material yield, use the finished thickness to figure out what you'll actually have to work with.
Frequently Asked Questions
How many board feet are in a standard 2×4×8?
Using nominal dimensions: (2 × 4 × 8) ÷ 12 = 5.33 board feet. Using actual dimensions (1.5" × 3.5"): (1.5 × 3.5 × 8) ÷ 12 = 3.5 board feet. Construction lumber from a home center is typically priced by linear foot, not board feet, so this distinction mainly matters when pricing hardwood from a specialty dealer.
How do I convert board feet to cubic feet?
Divide board feet by 12. One board foot = 144 cubic inches = 1/12 cubic foot. So 60 board feet = 5 cubic feet. This conversion is useful for calculating shipping weights or storage space.
Can I use this calculator for metric lumber?
Yes — the calculator accepts centimeter inputs. For metric lumber, convert your dimensions (cm to inches for thickness and width, cm to feet for length), or use the cm input option and the calculator converts internally. Note that board feet is a North American standard; European lumber is often sold by cubic meters.
Lumber prices shown are illustrative ranges only and vary by region, supplier, grade, and market conditions. Always obtain current quotes from your local lumber yard before finalizing project budgets.
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