How to Calculate Board Feet of Lumber
Formula, Examples, and MBF Explained
Before you can price a hardwood order, quote a sawmill, or compare lumber costs across board dimensions, you need to convert physical size into board feet. This guide covers the formula, worked examples, nominal vs actual dimensions, and current hardwood pricing.
This guide covers hardwood and sawmill lumber pricing. If you need board feet for framing, decking, or structural softwood, see the softwood framing lumber guide →
Skip the math. Enter your lumber dimensions in the board foot calculator, get BF, MBF, and cost in seconds.
Use the calculator →A board foot is a unit of volume. Before you can price a hardwood order, quote a sawmill, or compare lumber costs across different board dimensions, you need to convert the physical size of your lumber into board feet.
The board foot formula
The formula uses three measurements: thickness in inches, width in inches, and length in feet. Divide the product of all three by 12. Always use nominal dimensions: the labeled size at the lumber yard, not the actual milled size.
Board Foot Formula
BF = (T″ × W″ × L') ÷ 12
Example 1: Framing lumber. A 2×8 at 16 feet: (2 × 8 × 16) ÷ 12 = 21.33 BF. Ordering 25 pieces: 25 × 21.33 = 533 BF total.
Example 2: Hardwood slab. A 4/4 walnut board (nominal 1″ thick) at 9 inches wide and 7 feet long: (1 × 9 × 7) ÷ 12 = 5.25 BF. At $18/BF: $94.50 for that board.
Example 3: Structural timber. A 6×8 at 14 feet: (6 × 8 × 14) ÷ 12 = 56 BF per piece. Twelve such beams: 672 BF = 0.672 MBF. Use the board foot calculator for fast totals on any size and quantity.
Board feet per piece: quick reference
| Nominal size | 8 ft | 10 ft | 12 ft | 16 ft | BF per LF |
|---|---|---|---|---|---|
| 1×6 | 4.00 | 5.00 | 6.00 | 8.00 | 0.50 |
| 2×4 | 5.33 | 6.67 | 8.00 | 10.67 | 0.67 |
| 2×6 | 8.00 | 10.00 | 12.00 | 16.00 | 1.00 |
| 2×8 | 10.67 | 13.33 | 16.00 | 21.33 | 1.33 |
| 2×10 | 13.33 | 16.67 | 20.00 | 26.67 | 1.67 |
| 2×12 | 16.00 | 20.00 | 24.00 | 32.00 | 2.00 |
| 6×6 | 24.00 | 30.00 | 36.00 | 48.00 | 3.00 |
The 2×6 is easiest to verify mentally: its BF yield equals its length in feet exactly. For large-section timber and logs, the timber volume calculator handles BF, cubic feet, MBF, and weight in one step.
Nominal vs actual dimensions
| Nominal size | Actual size | BF per LF |
|---|---|---|
| 2×4 | 1.5″ × 3.5″ | 0.67 |
| 2×6 | 1.5″ × 5.5″ | 1.00 |
| 2×8 | 1.5″ × 7.25″ | 1.33 |
| 2×10 | 1.5″ × 9.25″ | 1.67 |
| 2×12 | 1.5″ × 11.25″ | 2.00 |
| 6×6 | 5.5″ × 5.5″ | 3.00 |
Board foot calculations always use nominal. Coverage calculations (how many boards span a width) always use actual. For deck board spacing using actual dimensions correctly, the board spacing calculator finds the exact gap for even spacing.
Hardwood pricing per board foot
| Species | Grade | Price per BF |
|---|---|---|
| Poplar | FAS | $4.00–$8.50 |
| Red Oak | #1 Common | $3.00–$5.00 |
| Red Oak | FAS | $7.00–$10.50 |
| Cherry | FAS | $8.00–$14.75 |
| Hard Maple | FAS | $9.00–$16.00 |
| Walnut | FAS | $15.00–$25.00 |
Boards wider than 9 inches carry a $1–$2/BF premium. For fence board volume calculations, the fence board calculator handles the full material list. For beam sizing before calculating timber volume, see how to size a beam.
Fence boards and exterior lumber in board feet
Board foot calculations apply directly to fence board orders. A privacy fence using 1×6 boards (nominal 1-inch thick, 6 inches wide) has a board foot yield of 0.50 BF per linear foot. For a 150-foot fence requiring 360 boards cut to 6 feet each: 360 × (1 × 6 × 6) ÷ 12 = 360 × 3 = 1,080 BF total. At 20 posts cut to 9 feet from 4×4 stock: 20 × (4 × 4 × 9) ÷ 12 = 20 × 12 = 240 BF. The fence post stock adds 22% more board feet to the order that most estimators forget when pricing from the board count alone. For a complete fence material list including posts, rails, and concrete, the fence board calculator handles the full take-off without a separate BF calculation.
For structural timber purchases (beams, heavy posts, 6×6 and larger) the volume per piece is large enough that BF calculations directly drive the wholesale price conversation. A single 16-foot 6×12 beam contains 96 BF: more than the combined volume of six 16-foot 2×6 framing joists. When ordering from a sawmill, the timber volume calculator converts any beam or post dimension directly to board feet, cubic feet, MBF, and estimated weight, making it the faster tool for large-section structural timber orders where the BF total determines the invoice.
Frequently asked questions
Where does the board foot unit come from, and why is it still used today?
The board foot originated in the North American timber trade as a practical way to measure and price logs and rough-sawn lumber before standardized dimensions existed. Sawmills cutting irregular slabs needed a volume measure that worked regardless of board width. The unit persisted because hardwood dealers never adopted standard dimensions: a 5/4 walnut slab and a 4/4 maple board require volume pricing to compare fairly. Softwood framing shifted to linear feet at retail, but board feet remain the language of structural timbers, hardwoods, and sawmill pricing worldwide.
Why does the board foot formula use nominal dimensions instead of actual milled dimensions?
Nominal dimensions (2×4, 2×6, etc.) reflect the rough-sawn size when the lumber was first cut at the mill. The actual milled size is smaller because surfacing removes material. Since pricing and grading happen before surfacing, the entire supply chain from sawmill to distributor uses nominal dimensions. Using actual dimensions would require recalculating every order at every stage of distribution. The convention is so entrenched that trade associations like the NHLA specify board foot calculation using nominal dimensions in their official grading rules.
How do I use board feet to compare the cost per unit volume of different lumber dimensions?
Divide the price of a board by its board foot content to get cost per BF. A 2×4×8 at $5.40 contains 5.33 BF, costing $1.01/BF. A 2×6×8 at $7.80 contains 8 BF, costing $0.98/BF. The wider board costs slightly less per unit of wood. This comparison is useful when deciding between structural alternatives, if a 2×10 and three 2×4s have the same BF content and structural adequacy, the cheapest option per BF is the better purchase. Lumber yards often discount larger-dimension pieces per BF compared to smaller framing lumber.
At what project scale does switching from board feet to MBF pricing become worthwhile?
MBF pricing becomes relevant when ordering above roughly 500–1,000 board feet, typically a mid-size custom home, large commercial framing job, or direct mill purchase. Below that threshold, retail pricing per BF is easier to manage. Above 1 MBF, suppliers offer tiered pricing and mills quote directly, with discounts of 15–30% compared to retail BF pricing. For estimating purposes, always convert to BF first to verify your takeoff, then convert to MBF for the purchase order when dealing with wholesale suppliers.
Why is hardwood priced per board foot but softwood by the linear foot?
Hardwood comes in random widths and lengths: pricing per board foot accounts for all three dimensions and fairly values irregular stock. Standard softwood framing lumber is milled to fixed widths and sold at retail by the piece or linear foot because every 2×6 at a given length contains the same volume.
What is the difference between nominal and actual lumber dimensions?
Nominal dimensions are the labeled sizes (2×4, 2×6). Actual dimensions are the milled sizes after drying and planing. A nominal 2×4 is actually 1.5 × 3.5 inches. Board foot calculations always use nominal. Coverage calculations always use actual.
How do I calculate board feet for a timber framing project?
Calculate BF for each timber size separately: BF = (T × W × L) ÷ 12. A 6×8 at 14 feet = 56 BF per piece. Ten pieces = 560 BF = 0.56 MBF. Sum each line item in your cut list to get total order volume for a sawmill quote.
What are current lumber prices per board foot?
Early 2026 retail hardwood: Red Oak FAS $7–$10.50/BF, Cherry $8–$14.75/BF, Walnut $15–$25/BF, Hard Maple $9–$16/BF. Softwood framing: 2×4 SPF $0.51–$0.66/LF, 2×6 SPF $0.84/LF, 2×10 DF-L $1.98–$2.03/LF.
References
National Hardwood Lumber Association. (2023). Rules for the Measurement and Inspection of Hardwood and Cypress. NHLA. nhla.com
Hearne Hardwoods. (January 2026). Hearne Hardwoods Price List. hearnehardwoods.com
Western Wood Products Association. (2024). Western Lumber Product Use Manual. WWPA. wwpa.org
Capitol City Lumber. (2026). Nominal and Actual Lumber Dimensions. capitolcitylumber.com
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