Board Foot Calculator
Calculate board feet and estimate lumber cost from board dimensions. Supports common lumber sizes, imperial and metric units, and volume conversions for accurate material ordering.
Number of Boards
Lumber Dimensions
Cost Estimation
(Optional)Lumber Volume
1 board at 1.5 in × 3.5 in × 8 ft equals 3.50 board feet (504.0 in³).
How many board feet do you actually need?
Whether you’re buying hardwood for a furniture project or softwood for framing, board feet is the language lumber yards speak. Our board foot calculator converts your board dimensions into precise volume measurements so you can order exactly what you need — no more guessing, no more overbuying.
Board footage is a volume measurement unique to lumber. Unlike square footage (area) or linear footage (length), board feet accounts for all three dimensions of a board: thickness, width, and length. Getting this number right means avoiding costly mistakes, especially when buying premium hardwoods at $10-20 per board foot.
How to calculate board feet by hand
The board foot formula is straightforward once you know the units:
Key detail: Length must be in feet, while thickness and width must be in inches. Mixing units is the most common mistake.
Step-by-step:
- Measure thickness in inches. For surfaced lumber, use actual dimensions (e.g., 1.5” for a 2×).
- Measure width in inches. Again, use actual dimensions (e.g., 3.5” for a nominal 4” board).
- Measure length in feet. Convert inches to feet by dividing by 12.
- Multiply all three, then divide by 12.
Example: A board that is 1.5” thick × 5.5” wide × 10’ long:
Common lumber board foot examples
These are the board feet for popular lumber sizes you will encounter at most lumber yards, calculated using the standard board foot formula:
| Lumber Size | Board Feet |
|---|---|
| 2×4×8 ft | 5.33 |
| 2×4×10 ft | 6.67 |
| 2×4×12 ft | 8.00 |
| 2×4×16 ft | 10.67 |
| 2×6×8 ft | 8.00 |
| 2×6×10 ft | 10.00 |
| 2×6×12 ft | 12.00 |
| 2×8×8 ft | 10.67 |
| 4×4×8 ft | 10.67 |
| 4×4×10 ft | 13.33 |
These values are approximate quick-reference estimates based on the standard board foot formula and nominal lumber dimensions. For custom board sizes, non-standard lengths, or precise multi-board calculations, use the calculator above to get exact board footage for your project.
Converting board feet to other units
Board feet converts to several useful volume measurements:
For metric users:
These conversions help when comparing lumber volumes to other materials or when working with metric tooling and specifications.
Tips for buying lumber by the board foot
- Always use actual dimensions. Nominal sizes (2×4, 4×4) are marketing labels. The actual size is smaller after drying and planing.
- Add 10-15% for waste. Cuts, defects, and grain matching all consume extra material.
- Buy all at once. Wood color and grain vary between batches. Matching stock later is nearly impossible.
- Ask about rough-sawn vs. surfaced. Rough-sawn lumber is sold at nominal dimensions, while surfaced (S4S) lumber is sold at actual dimensions.
- Check for defects. Knots, checks, and twist reduce usable volume. Factor this into your waste percentage.
Planning a larger project?
Board feet calculations are one piece of the puzzle. These related tools can help you plan the full scope:
- Deck Calculator — Estimate decking boards, fasteners, and total cost
- Flooring Calculator — Calculate flooring material for indoor spaces
- Tile Calculator — Estimate tiles for walls and floors
Frequently Asked Questions
Common questions about this calculator.
What is a board foot?
A board foot is a unit of lumber volume equal to 1 inch thick × 12 inches wide × 12 inches long, or 144 cubic inches. It is the standard measurement used in North American lumber yards for pricing and selling hardwood and softwood. One board foot equals 1/12 of a cubic foot, or approximately 2.36 liters. Because it accounts for thickness, width, and length, board feet is the most accurate way to measure wood volume when purchasing lumber. You will typically see prices quoted per board foot, especially for hardwoods like oak, maple, and walnut.
What is a board foot calculator?
A board foot calculator is a tool that converts lumber dimensions — thickness, width, and length — into board feet, the standard volume measurement for buying and selling wood. Rather than manually working through the formula, you enter your board dimensions and get an instant result. This helps woodworkers, contractors, and DIYers estimate how much lumber they need, compare prices between suppliers, and avoid overbuying or underordering materials for furniture, framing, or woodworking projects.
How do I calculate a board foot?
Use the board foot formula: Board Feet = (Thickness in inches × Width in inches × Length in feet) ÷ 12. For example, a board that is 1.5 inches thick, 5.5 inches wide, and 10 feet long equals (1.5 × 5.5 × 10) ÷ 12 = 6.875 board feet. Always use actual measured dimensions rather than nominal sizes, and make sure length is in feet while thickness and width are in inches.
How many board feet is a 2×4×8?
A 2×4 that is 8 feet long contains 3.50 board feet using actual dimensions (1.5 inches × 3.5 inches). The calculation is (1.5 × 3.5 × 8) ÷ 12 = 3.50 BF. At nominal dimensions (2 × 4), the same board would be (2 × 4 × 8) ÷ 12 = 5.33 BF. Always confirm whether your lumber is sold at nominal or actual size when estimating material needs.
How many board feet is a 2×4×10?
A 2×4 that is 10 feet long contains 4.38 board feet using actual dimensions (1.5 inches × 3.5 inches). The math: (1.5 × 3.5 × 10) ÷ 12 = 4.375 BF. At nominal dimensions, the same board would be (2 × 4 × 10) ÷ 12 = 6.67 BF. This is a common size for wall framing and general construction.
How many board feet is a 2×6×10?
A 2×6 that is 10 feet long contains 6.88 board feet using actual dimensions (1.5 inches × 5.5 inches). The calculation: (1.5 × 5.5 × 10) ÷ 12 = 6.875 BF. At nominal dimensions, the same board would be (2 × 6 × 10) ÷ 12 = 10.0 BF. Wider boards like 2×6s are commonly used for floor joists, headers, and shelving.
How many board feet are in a 2×2×12?
A 2×2 that is 12 feet long contains 2.25 board feet using actual dimensions (1.5 inches × 1.5 inches). The formula gives (1.5 × 1.5 × 12) ÷ 12 = 2.25 BF. At nominal dimensions, the same board would be (2 × 2 × 12) ÷ 12 = 4.0 BF. Smaller dimension lumber like 2×2s is often used for trim, furniture frames, and light woodworking projects.
How many board feet are in a 2×4×16?
A 2×4 that is 16 feet long contains 7.0 board feet using actual dimensions (1.5 inches × 3.5 inches). The calculation: (1.5 × 3.5 × 16) ÷ 12 = 7.0 BF. At nominal dimensions, the same board would be (2 × 4 × 16) ÷ 12 = 10.67 BF. Longer boards like this are common in framing walls and building roof structures.
What does 20 board feet mean?
20 board feet represents a volume of lumber equivalent to 20 individual boards each measuring 1 inch thick × 12 inches wide × 12 inches long. In practical terms, this could be a single large board or several smaller pieces combined. For example, you might get 20 board feet from three 2×6×10 boards (about 20.6 BF total). Board feet is the standard purchasing unit for lumber, so understanding this measurement helps you compare prices, estimate project costs, and order the right amount of hardwood or softwood for your needs.
How much area will 200 board feet cover?
Board feet is a volume measurement, not an area measurement, so the coverage depends on the thickness of the lumber. For 1-inch thick boards, 200 board feet covers approximately 200 square feet. For 2-inch thick boards, the same volume covers about 100 square feet. To estimate area coverage, divide the total board feet by the thickness in inches. This is useful when planning flooring, decking, or paneling projects where you need to know how much square footage your lumber purchase will cover.
What is the difference between nominal and actual lumber dimensions?
Nominal dimensions like 2×4 refer to the board's size before drying and planing, while actual dimensions like 1.5×3.5 for a 2×4 are the finished size after processing. Lumber is sold by its nominal name, but board feet calculations must use actual dimensions. Using nominal sizes overestimates volume by roughly 20 to 75 percent depending on the board, which can lead to ordering too much material and overspending.
How much does a board foot of hardwood cost?
Hardwood prices vary widely by species, grade, and region. Common hardwoods like red oak or maple typically cost $3 to $8 per board foot. Premium species such as walnut, cherry, or exotic woods can range from $8 to $25 or more per board foot. Softwoods like pine, cedar, and fir are generally $1 to $4 per board foot. Buying rough-sawn lumber in bulk or directly from a sawmill can reduce costs, while surfaced and kiln-dried stock commands a premium.