Board Foot Calculator

What Is a Board Foot?

The board foot calculator above computes lumber volume using the board foot — the standard unit in the North American hardwood trade and increasingly used by softwood suppliers. One board foot equals 144 cubic inches — the same as a piece of wood 1 foot long, 1 foot wide, and 1 inch thick. The unit exists because lumber is sold by volume, not just length, since boards vary widely in width and thickness. A thick, wide board contains significantly more wood than a thin, narrow one of the same length, and board feet capture that difference in a single number.

Board feet are used throughout the lumber industry for several purposes:

• Hardwood pricing — all hardwood lumber (oak, walnut, maple, cherry) is priced and sold by the board foot at retail, wholesale, and sawmill level per NHLA (National Hardwood Lumber Association) grading rules
• Softwood framing estimates — while framing lumber is sold by the stick at home improvement stores, contractors and material estimators track total board footage to compare bids and cost-per-BF across species and grades
• Timber and log purchasing — standing timber and rough-sawn logs are quoted in MBF (thousand board feet)
• Custom millwork — cabinetmakers, furniture makers, and finish carpenters calculate shop material in board feet to cost out projects and minimize waste

The key distinction to understand: board feet use nominal dimensions (the stated size), not actual milled dimensions. A "2×4" is nominally 2 in × 4 in but actually measures 1.5 in × 3.5 in after surfacing. Lumber is purchased and priced on nominal dimensions — actual dimensions are used only for structural calculations.

How to Calculate Board Feet

A board foot is a unit of lumber volume equal to 144 cubic inches — equivalent to a piece of wood 1 foot long, 1 foot wide, and 1 inch thick. To calculate board feet, you need three measurements: thickness (in inches), width (in inches), and length (in feet). Multiply them together and divide by 12:

Board Feet = (Thickness″ × Width″ × Length′) ÷ 12

For multiple boards, multiply the result by quantity. Always use nominal dimensions — the stated size before milling — when calculating board feet for purchasing. A "2×4" is listed and priced at 2 in × 4 in even though its actual milled size is 1.5 in × 3.5 in.

Step-by-Step Example

1. Identify the thickness, width, and length in the correct units (inches for thickness and width, feet for length)
2. Enter the values and quantity in the calculator above
3. Optionally enter your price per board foot for an instant cost estimate
4. Read off your total board footage and cost below

Board Foot Formula — Examples and Common Lumber Sizes

The board foot formula applies to any rectangular piece of wood. Here are worked examples for the most common dimensional lumber sizes:

• 1×4 × 8 ft: (1 × 4 × 8) ÷ 12 = 2.67 bf
• 1×6 × 8 ft: (1 × 6 × 8) ÷ 12 = 4.00 bf
• 2×4 × 8 ft: (2 × 4 × 8) ÷ 12 = 5.33 bf
• 2×6 × 8 ft: (2 × 6 × 8) ÷ 12 = 8.00 bf
• 2×8 × 10 ft: (2 × 8 × 10) ÷ 12 = 13.33 bf
• 4×4 × 8 ft: (4 × 4 × 8) ÷ 12 = 10.67 bf
• 4×6 × 12 ft: (4 × 6 × 12) ÷ 12 = 24.00 bf

For non-standard sizes like rough-cut hardwood slabs, measure the actual thickness and width in inches and enter them above. The formula is identical — just replace the nominal dimensions with actual measured ones.

Board Feet vs. Linear Feet — What's the Difference?

A linear foot is simply a length measurement: one foot along the length of a board, regardless of its cross-section. A board foot measures volume, accounting for thickness and width as well. Hardwood is almost always sold by the board foot because a wider or thicker board contains more wood. Softwood framing lumber (studs, joists) is often sold by the linear foot at a fixed price per piece, but contractors and suppliers still track totals in board feet.

To convert board feet to linear feet for a specific size: Linear feet = Board feet ÷ ((Thickness″ × Width″) ÷ 12). For a 2×6, the cross-section factor is (2 × 6) ÷ 12 = 1.0, so board feet equal linear feet. For a 1×4, the factor is 0.333, so 10 board feet equals 30 linear feet of 1×4. If you are estimating fence pickets, deck boards, or trim runs, also check out our linear foot calculator for planning those projects.

How to Estimate Lumber Cost

Lumber is priced in board feet in the hardwood trade, and increasingly in softwood yards as well. To estimate your cost, multiply total board feet by the price per board foot. For example, 50 board feet of white oak at $4.50/bf would cost $225. Add 10–15% for waste, end checks, and defects when purchasing rough-cut hardwood.

Typical 2025 retail prices by species:

• Common softwoods (pine, fir, SPF): $0.50–$2.00/bf
• Red oak / white oak / hard maple: $3.00–$6.00/bf
• Cherry / ash / soft maple: $5.00–$10.00/bf
• Black walnut: $8.00–$15.00/bf
• Exotic and figured hardwoods: $15–$30+/bf

Prices fluctuate significantly with lumber market conditions. Always get a current quote from your local sawmill or lumber yard before finalizing a budget. If you are planning a concrete deck or slab to support a structure, our concrete slab calculator can help you estimate those material costs as well.

Common Lumber Dimensions and Board Foot Equivalents

Dimensional lumber in North America is sold in nominal sizes. The actual (milled) dimensions are always smaller due to surfacing. Board footage is always calculated from nominal dimensions for purchasing purposes. Here is a quick reference for standard 8-foot lengths:

• 1×2 × 8 ft — 1.33 bf (actual: 0.75″ × 1.5″)
• 1×4 × 8 ft — 2.67 bf (actual: 0.75″ × 3.5″)
• 1×6 × 8 ft — 4.00 bf (actual: 0.75″ × 5.5″)
• 1×8 × 8 ft — 5.33 bf (actual: 0.75″ × 7.25″)
• 2×4 × 8 ft — 5.33 bf (actual: 1.5″ × 3.5″)
• 2×6 × 8 ft — 8.00 bf (actual: 1.5″ × 5.5″)
• 2×8 × 8 ft — 10.67 bf (actual: 1.5″ × 7.25″)
• 2×10 × 8 ft — 13.33 bf (actual: 1.5″ × 9.25″)
• 2×12 × 8 ft — 16.00 bf (actual: 1.5″ × 11.25″)
• 4×4 × 8 ft — 10.67 bf (actual: 3.5″ × 3.5″)
• 6×6 × 8 ft — 24.00 bf (actual: 5.5″ × 5.5″)

For rough-sawn hardwood slabs, there are no standard sizes — always measure the actual thickness and width with a tape or calipers before entering values in the calculator. Round to the nearest 1/8 inch for accuracy.