Lumber Board Foot Calculator
Calculate board feet of lumber for pricing and estimating wood materials
Lumber Item 1
Nominal or actual
Pricing (optional)
Hardwood is priced on actual; softwood/framing on nominal
Results
Step-by-Step Calculation
What Is a Board Foot?
A board foot (BF) is the standard unit of measure for lumber volume in the United States and Canada. One board foot equals a piece of wood that is 1 inch thick × 12 inches wide × 12 inches long, or 144 cubic inches of wood.
Board Foot Formula:
Board Feet = (Thickness" × Width" × Length') ÷ 12
When all measurements are in inches:
Board Feet = (Thickness" × Width" × Length") ÷ 144
Examples:
- 1" × 12" × 1' = (1 × 12 × 1) ÷ 12 = 1.00 BF
- 1" × 6" × 8' = (1 × 6 × 8) ÷ 12 = 4.00 BF
- 2" × 4" × 8' = (2 × 4 × 8) ÷ 12 = 5.33 BF
- 2" × 6" × 12' = (2 × 6 × 12) ÷ 12 = 12.00 BF
- 4" × 4" × 10' = (4 × 4 × 10) ÷ 12 = 13.33 BF
Nominal vs. Actual Lumber Sizes
Lumber is sold using nominal sizes (the name, like "2×4") but the actual dimensions are smaller due to drying and planing. Softwood/framing lumber is typically priced by the piece or linear foot using nominal sizes. Hardwood lumber is priced per board foot using actual (measured) dimensions.
| Nominal | Actual (inches) | Actual (mm) | BF per 8' board |
|---|---|---|---|
| 1×4 | 3/4" × 3-1/2" | 19 × 89 | 2.67 |
| 1×6 | 3/4" × 5-1/2" | 19 × 140 | 4.00 |
| 1×8 | 3/4" × 7-1/4" | 19 × 184 | 5.33 |
| 1×10 | 3/4" × 9-1/4" | 19 × 235 | 6.67 |
| 1×12 | 3/4" × 11-1/4" | 19 × 286 | 8.00 |
| 2×4 | 1-1/2" × 3-1/2" | 38 × 89 | 5.33 |
| 2×6 | 1-1/2" × 5-1/2" | 38 × 140 | 8.00 |
| 2×8 | 1-1/2" × 7-1/4" | 38 × 184 | 10.67 |
| 2×10 | 1-1/2" × 9-1/4" | 38 × 235 | 13.33 |
| 2×12 | 1-1/2" × 11-1/4" | 38 × 286 | 16.00 |
| 4×4 | 3-1/2" × 3-1/2" | 89 × 89 | 10.67 |
| 4×6 | 3-1/2" × 5-1/2" | 89 × 140 | 16.00 |
| 6×6 | 5-1/2" × 5-1/2" | 140 × 140 | 24.00 |
How Lumber Is Priced
Hardwood (by Board Foot)
Hardwood lumber (oak, maple, walnut, cherry) is sold by the board foot at the actual measured dimensions.
- • Thickness expressed in "quarters" (4/4 = 1", 6/4 = 1.5", 8/4 = 2")
- • Width and length vary by board
- • Price is per board foot ($/BF)
- • Typical range: $3-$15+ per BF depending on species
Softwood / Framing (by Piece)
Softwood framing lumber (pine, spruce, fir) is typically sold by the piece or linear foot at nominal dimensions.
- • Sold in standard lengths (8', 10', 12', 16')
- • Named by nominal size (2×4, 2×6, etc.)
- • Price is per piece or per linear foot
- • Board feet still used for large orders
Hardwood Thickness Reference (Quarter System)
| Quarter Notation | Rough Thickness | Surfaced (S2S) | Common Use |
|---|---|---|---|
| 4/4 | 1" | 3/4" (13/16") | Shelving, panels, trim, small projects |
| 5/4 | 1-1/4" | 1-1/16" | Decking, stair treads |
| 6/4 | 1-1/2" | 1-5/16" | Tabletops, thick shelves |
| 8/4 | 2" | 1-3/4" | Table legs, heavy duty projects |
| 10/4 | 2-1/2" | 2-1/4" | Turning blanks, thick workpieces |
| 12/4 | 3" | 2-3/4" | Mantels, heavy timber, carving |
Lumber Buying Tips
- Always buy 10-15% extra to account for defects, knots, warping, and cutting waste
- Inspect each board in person when possible — check for twist, bow, cup, and crook
- Hardwood boards vary in width and length; calculate board feet for each board individually at the yard
- Ask if the quoted price includes surfacing (S2S or S4S) or if rough-sawn is cheaper
- Kiln-dried (KD) lumber is more stable than air-dried — specify for furniture and interior projects
- Some yards round up each board to the nearest BF; ask about their rounding policy
- For large orders, ask about volume discounts — many hardwood dealers offer tiered pricing
- Consider lumber grade: FAS (best), Select, #1 Common, and #2 Common each have different yield
Related Calculators
Note: Board foot calculations are based on the dimensions you enter. For nominal softwood sizes, the board footage uses the nominal dimensions (what you call it, not the actual planed size). For hardwood, board footage is calculated on actual measured thickness, width, and length. Always confirm pricing and measurement methods with your lumber supplier.
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