SamCalculator

Board Foot Calculator

Calculate board feet, lumber costs, material quantities, and wood project estimates for construction, woodworking, and furniture projects.

Lumber dimensions

Calculator mode

Nominal size:

Each board ≈ 10.000 bf

Enter your lumber dimensions above and press Calculate to reveal board feet, lumber volume, costs, a cut-list summary, board-size comparison, and project insights.

What is a board foot?

A board foot calculator turns a board's three measurements — thickness, width, and length — into the standard unit lumber is sold by: the board foot. One board foot is a piece of wood one foot wide, one foot long, and one inch thick, equal to 144 cubic inches or one-twelfth of a cubic foot. It is the universal currency of sawmills, lumber yards, and woodworking shops, so knowing how many board feet a project needs is the difference between a confident order and an expensive guess.

This tool does far more than a single thickness × width × length box. It calculates board feet for a single board, several identical boards, or a mixed lumber stack with dozens of different sizes; converts the result into cubic feet, cubic inches, cubic yards, and cubic metres; applies a waste factor; estimates cost from a price per board foot; compares prices across eleven common wood species; and rounds up to a recommended purchase quantity. Whether you are pricing a hardwood dining table, framing a deck, or buying paneling, the goal is the same: order the right amount of lumber the first time.

How to calculate board feet

Measure thickness, width, and length

Measure the board's thickness and width in inches and its length in feet. If you only have metric measurements, the calculator converts millimetres and centimetres for thickness and width, and metres for length, so the units always line up before the maths.

Multiply, then divide by 12

Multiply thickness × width × length and divide by 12. The 12 appears because thickness and width are in inches but length is in feet — there are 12 inches in a foot. A 2 in × 6 in × 10 ft board is (2 × 6 × 10) ÷ 12 = 10 board feet.

Add up multiple boards

For several identical boards, find the board feet of one and multiply by the quantity. For a mixed cut list, calculate each size separately and add the totals — exactly what the Multiple Boards and Lumber Stack modes do automatically.

Apply a waste factor and price it

Lumber is lost to saw kerf, knots, end-checks, and cutting around defects, so add a 10–15% waste factor. Multiply the total board feet by your price per board foot to budget the project, then round up to whole board feet for the order.

3 ways to use this calculator

1

Price a single board

Enter one board's thickness, width, and length to get its exact board footage and cost — perfect for checking a yard's quote or comparing two boards at the rack.

2

Estimate a full cut list

Switch to the Lumber Stack mode and add a row for every board size your project needs. The calculator totals the board feet, volume, and cost across the whole list in one step.

3

Compare species and budget

Pick a wood species to see a typical price, then compare what the same project would cost in pine, oak, maple, walnut, and more — with a waste factor and recommended purchase quantity built in.

Nominal size vs actual size

Softwood dimensional lumber is named by its nominal size — the rough size before it was milled and dried — not its finished size. A "2×4" actually measures about 1-1/2 × 3-1/2 inches once it has been surfaced on all four sides, and a "1×6" is really 3/4 × 5-1/2 inches. The wood was that size when first sawn; planing and drying shrink it.

Here is the catch that trips people up: softwood lumber is bought, sold, and board-footed by its NOMINAL size, even though you receive the smaller actual board. So a 2×4×8 is billed as 5.33 board feet using 2 × 4 × 8, not the 4 board feet its real dimensions would suggest. Hardwood is different — it is usually sold rough (full thickness, in quarter-inch "4/4, 5/4, 6/4" steps) and board-footed by its actual rough size. When in doubt, enter the dimensions your supplier prices by.

NominalActual (surfaced)Board feet (8 ft)
1 × 43/4" × 3-1/2"2.67 bf
1 × 63/4" × 5-1/2"4.00 bf
1 × 83/4" × 7-1/4"5.33 bf
1 × 123/4" × 11-1/4"8.00 bf
2 × 41-1/2" × 3-1/2"5.33 bf
2 × 61-1/2" × 5-1/2"8.00 bf
2 × 81-1/2" × 7-1/4"10.67 bf
2 × 101-1/2" × 9-1/4"13.33 bf
2 × 121-1/2" × 11-1/4"16.00 bf
4 × 43-1/2" × 3-1/2"10.67 bf

Tips for buying lumber

  • Add a 10% waste factor for simple, straight cuts and 15–20% for projects with lots of short pieces, angles, or grain matching.
  • Buy hardwood a little long — boards are sold in random lengths and you will trim checked or split ends off both sides.
  • Board-foot softwood by its nominal size (2×4, 1×6) and hardwood by its actual rough thickness so your figure matches the yard's quote.
  • For mixed projects, build the full cut list in the Lumber Stack mode rather than guessing a single average board size.
  • Compare price per board foot, not price per board — a wide, long board can look expensive but cost less per board foot than a small one.
  • Order all of one species and grade in a single trip so the color and figure match across the finished piece.

Why lumber is sold by the board foot

Lumber is sold by the board foot because boards come in wildly different widths, lengths, and thicknesses, and a single price per piece would be meaningless. A board foot measures the actual volume of wood — 144 cubic inches — so a narrow short board and a wide long board can be compared fairly on a single price-per-board-foot basis. That is how sawmills, wholesalers, and retail yards have priced solid wood for well over a century.

Getting the board-foot count right matters because lumber is one of the larger line items in any build, and a small error multiplies fast. Under-order and the project stalls while you make a second trip — and the new boards may not match the color or grain of the first batch. Over-order and you have paid for expensive hardwood that now sits in the rack. An accurate board-foot figure, adjusted for a sensible waste factor and priced in your currency, keeps the job on time and on budget while making sure every board matches.

Estimating lumber cost & hardwood pricing

To estimate lumber cost, multiply the total board feet by the price per board foot. A project needing 40 board feet of oak at $7 per board foot costs about $280 in material before waste — add a 10–15% waste factor and round up, and you would budget closer to $315. Always price by the board foot rather than per board, because boards are random-width and a single per-piece price hides how much wood you are actually buying.

Hardwood pricing climbs with rarity, board width, length, and grade. Common species like poplar and red oak sit at the low end; walnut, cherry, and figured boards command a premium. Wider and longer boards cost more per board foot because they yield more clear, usable wood and are harder for the mill to produce. Higher grades such as FAS and Select cost more per board foot but waste less, so the cheapest grade is not always the cheapest finished project — factor your expected yield into the comparison.

Real-life lumber projects

2×6×10 framing board

A single 2 in × 6 in × 10 ft board is (2 × 6 × 10) ÷ 12 = 10 board feet. At a softwood price of about $4 per board foot, that one board costs roughly $40 before tax and delivery.

Hardwood dining table

A solid-oak table with a 5-board top, four legs, and aprons runs around 60–70 board feet. At $7 per board foot plus a 15% waste factor, budget roughly $500–600 in oak alone — confirm with your hardwood dealer's current price list.

Deck construction

A 12 × 12 ft cedar deck with decking, joists, and beams totals several hundred board feet. Treat each component as its own row in the Lumber Stack, add a 10% waste factor, and round up to whole board feet for the order.

Kitchen cabinet build

A run of maple cabinets — carcasses, face frames, and shelves — typically needs 80–120 board feet of solid stock plus sheet goods. Build the cut list as a stack so every panel, rail, and stile is counted.

Bookshelf or built-in

A pine bookshelf with four shelves and two sides in 1×12 stock is around 20–25 board feet. Pine's low price makes it forgiving, so a 10% waste factor is plenty for straight shelf cuts.

Wall paneling or flooring

Tongue-and-groove paneling and solid flooring are sold by the board foot too. Calculate the coverage you need, convert to board feet by board size, and add 10–15% for end-trimming and racking waste.

Core board foot formulas

Board feet (thickness, width in inches; length in feet)

(T in × W in × L ft) ÷ 12

The standard formula. A 1.5 in × 5.5 in × 10 ft board is (1.5 × 5.5 × 10) ÷ 12 = 6.875 board feet.

Board feet (all dimensions in inches)

(T in × W in × L in) ÷ 144

When length is also in inches, divide by 144 instead of 12, because one board foot is 144 cubic inches.

Total board feet

Board Feet × Quantity

Multiply one board's board footage by the number of identical boards, or add the totals of every size in a mixed cut list.

Board feet to cubic feet

Cubic Feet = Board Feet ÷ 12

A board foot is one-twelfth of a cubic foot, so 120 board feet is 10 cubic feet of solid wood.

With waste factor

Board Feet × (1 + Waste %)

40 board feet with a 15% waste factor is 46 board feet — round up to 46 bf when you place the order.

Estimated cost

Board Feet × Price per Board Foot

46 board feet of oak at $7 per board foot is about $322 in material before tax and delivery.

Common board foot calculation mistakes

1

Mixing up units in the formula

The formula uses thickness and width in inches but length in feet. Multiplying inches by inches by inches without dividing by 144 — or using feet for thickness — throws the answer off by a wide margin. Let the calculator's unit selectors keep it straight.

2

Forgetting to divide by 12

Thickness × width × length gives cubic inches-feet, not board feet. You must divide by 12 (length in feet) or 144 (length in inches). Skipping the division makes the count look twelve times too large.

3

Using actual size when you should use nominal

Softwood is board-footed by nominal size (2×4, 1×6), so using the smaller actual 1.5 × 3.5 in size undercounts what the yard will bill you. Match the size your supplier prices by.

4

Ignoring the waste factor

Saw kerf, knots, splits, and cutting around defects all consume wood. Ordering the exact board-foot count leaves you short — add 10–15%, more for hardwood or projects with many small parts.

How accurate is this calculator?

Every figure here uses the standard board-foot maths that sawmills, lumber yards, and woodworkers rely on: thickness (inches) × width (inches) × length (feet) ÷ 12 for a single board, multiplied by quantity and summed across a cut list, then adjusted by a transparent waste factor you control. Volume conversions use the exact relationships of 144 cubic inches and one-twelfth of a cubic foot per board foot, and the species prices are typical retail figures for surfaced, kiln-dried stock.

Treat the results as an accurate planning estimate, not a substitute for a supplier quote. Board-foot calculations are estimates based on the dimensions and assumptions you enter — actual lumber quantities, usable yield, nominal versus actual dimensions, and material costs vary with wood species, supplier standards, milling practices, grade, and project requirements. Confirm large or premium hardwood orders against your supplier's current price list and your own cut list before buying.

Frequently Asked Questions

A board foot is the standard unit of volume used to measure and sell lumber. It equals a piece of wood one foot long, one foot wide, and one inch thick — 144 cubic inches, or one-twelfth of a cubic foot. Because boards come in many widths, lengths, and thicknesses, the board foot lets sawmills, lumber yards, and woodworkers price very different boards on a single, fair basis: the actual amount of wood they contain.

Multiply the board's thickness in inches by its width in inches by its length in feet, then divide by 12. For example, a board 2 inches thick, 6 inches wide, and 10 feet long is (2 × 6 × 10) ÷ 12 = 10 board feet. If the length is also in inches, divide by 144 instead of 12. For several identical boards, multiply by the quantity; for a mixed cut list, calculate each size separately and add the totals.

The division by 12 converts the units so they match. A board foot is defined with thickness and width in inches but length in feet, and there are 12 inches in a foot. Multiplying thickness (in) × width (in) × length (ft) gives a figure 12 times too large, so dividing by 12 brings it back to true board feet. If you measure length in inches instead, you divide by 144, because one board foot contains 144 cubic inches.

Both measure volume, but at different scales. A board foot is 144 cubic inches — a board 12 × 12 inches and 1 inch thick. A cubic foot is 1,728 cubic inches — a cube 12 inches on every side. So one cubic foot contains exactly 12 board feet, and to convert board feet to cubic feet you divide by 12. Lumber is sold by the board foot because it suits the thin, flat shape of boards; bulk materials like concrete and gravel are sold by the cubic foot or cubic yard.

It depends on the length, and on whether you use nominal or actual size. Softwood lumber is board-footed by its nominal size, so a 2×4 uses 2 × 4 inches even though the milled board is really about 1-1/2 × 3-1/2 inches. An 8-foot 2×4 is (2 × 4 × 8) ÷ 12 = 5.33 board feet, a 10-foot 2×4 is 6.67 board feet, and a 12-foot 2×4 is 8 board feet. Most lumber yards price 2×4s by the piece or by the linear foot, but the board-foot figure is useful for comparing materials.

Nominal size is the name of the board — 2×4, 1×6 — and reflects its rough size before milling. Actual size is what you actually receive after the board is surfaced and dried, which is smaller: a 2×4 is about 1-1/2 × 3-1/2 inches and a 1×6 is about 3/4 × 5-1/2 inches. Importantly, softwood lumber is sold and board-footed by its nominal size, while hardwood is usually sold rough and board-footed by its actual size in quarter-inch thickness steps (4/4, 5/4, 6/4). Enter the size your supplier prices by.

Prices vary widely by species, grade, width, length, and region. Common softwoods like pine and spruce often run $3–6 per board foot, while construction-grade dimensional lumber is usually priced per piece. Hardwoods range from about $5 per board foot for poplar and red oak up to $10–15 or more for walnut, cherry, and mahogany, with figured or wide boards costing even more. This calculator uses typical retail figures as a starting point, but you should always confirm against your own supplier's current price list.

Yes. Wood is lost to saw kerf, splits and checks at board ends, knots, and cutting around defects, so ordering the exact calculated board feet usually leaves you short. Add about 10% for simple, straight cuts and 15–20% for projects with many short pieces, angled cuts, or hardwood that needs grain and color matching. After adding the waste factor, round up to whole board feet, since lumber is generally sold in whole-board increments.

The board-foot formula is identical for both — thickness × width × length ÷ 12. The difference is which dimensions you use. Softwood dimensional lumber is board-footed by its nominal size (2×4, 1×6), so you enter the nominal numbers. Hardwood is sold rough and board-footed by its actual rough size, often in quarter-inch thickness steps, so you enter the real measured dimensions. As long as you use the size your supplier prices by, the same calculator handles both.

The calculator applies the exact, industry-standard board-foot formula and volume conversions, so for the dimensions you enter the board-foot math is precise. The estimates that depend on assumptions — cost, waste, and species pricing — are only as accurate as the figures you provide. Default species prices are typical retail values that vary by region, grade, and supplier, and real-world yield depends on board defects and your cutting plan. Use the result as a reliable planning estimate, then confirm large or premium orders with your lumber dealer.

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