Skip to main content
True Trade Path

Calculator · Free

Board Foot Calculator

Convert lumber dimensions to board feet and price a material order.

Dimensions

Quarter notation is rough thickness before surfacing, and that is the thickness you are billed for.

in

Hardwood is measured at actual width, which is why the invoice rarely lands on a round number.

ft
Length is measured in
Order
$/bf

Leave at zero to skip the cost estimate.

One board foot is 144 cubic inches: thickness × width × length in inches, divided by 144. A board foot is a volume, not an area, so a 4/4 board 6 inches wide and 8 feet long and a 8/4 board 3 inches wide and 8 feet long are both 4 board feet.

Total board feet

40.00board feet

4.000 board feet per piece × 10 pieces.
Board feet per piece1.000" × 6.000" × 96.00" ÷ 144
4.000
Total costAt $6.50 per board foot
$260.00
Cost per piece
$26.00
Estimated weightKiln-dried hardwood at roughly 44 lb per cubic foot
147 lb
The same quantity expressed other ways
MeasureQuantityHow it is derived
Board feet40.00Thickness × width × length in inches ÷ 144
Cubic inches5,76040.00 bf × 144
Cubic feet3.3340.00 bf ÷ 12
Lineal feet of stock80.010 pieces × 8.00 ft
Surface measure (face area)40.0 sq ftWidth × length, ignoring thickness
Equivalent 1× stock 6" × 8'10.0 boardsEach is 4.00 board feet
Equivalent 2×4 × 8' nominal7.5 sticksEach is 5.33 board feet on nominal dimensions
Estimated weight147 lb44 lb per cubic foot, kiln dried
Material total$260.00

Order more than you measure

Board foot math gives you the volume in the pile, not the volume you can use. Rough hardwood loses width to jointing and length to checked or bowed ends, and a board with wane on one edge yields less than its tally. Most shops add 20 to 30% for a project with defined parts, more when the parts have to match for grain or color.

Softwood dimensional lumber is calculated on nominal dimensions — a 2×4 is billed as 2 by 4 even though it measures 1-1/2 by 3-1/2. Hardwood is the opposite and is calculated on actual measured width against rough thickness. This tool uses whatever you type, so enter nominal figures for construction lumber and measured figures for hardwood.

What this assumes

  • One board foot equals 144 cubic inches: thickness × width × length in inches, divided by 144.
  • Hardwood is priced on rough thickness in quarters, so 4/4 stock is billed as one inch even after surfacing.
  • Softwood dimensional lumber is calculated on nominal, not actual, dimensions.

Understanding the result

Quarter notation

Hardwood thickness is expressed in quarter inches: 4/4 is one inch, 8/4 is two inches. Lumber is measured and billed at its rough thickness before surfacing, so 4/4 stock that arrives at 13/16 inch is still sold and calculated as a full inch.

Nominal versus actual

A 2×4 measures 1.5 by 3.5 inches, but board foot calculations for construction lumber use the nominal 2 by 4. Hardwood is the opposite — it is calculated on actual measured width, which is why hardwood invoices rarely come out to round numbers.

Waste and defect allowance

Hardwood orders should include 10 to 15% extra for knots, checks, and end trim. A project calling for 50 board feet of clear 4/4 oak should be ordered as 55 to 58 board feet. Surfaced lumber loses thickness in milling — you pay for rough dimensions.

Pricing by the board foot

Hardwood is sold by the board foot at the rough thickness. A 4/4 board 6 inches wide and 8 feet long is 4 board feet (1 × 6 × 8 ÷ 12). At $8 per board foot, that single board costs $32. Wider and thicker stock costs more per board foot because fewer boards come from each log.

Common questions

How do you calculate board feet?
Board feet equals thickness in inches times width in inches times length in feet, divided by 12. A 2×4 that is 8 feet long: 2 × 4 × 8 ÷ 12 = 5.33 board feet. For hardwood, use actual measured dimensions — a surfaced 4/4 board measuring 5-1/2 inches wide is calculated at 5.5, not 6.
How many board feet in a 2x4x8?
A nominal 2×4×8 contains 5.33 board feet (2 × 4 × 8 ÷ 12). A full unit of 2×4×8 studs — typically 294 pieces — contains about 1,568 board feet. Construction lumber is priced per thousand board feet (MBF) in wholesale quantities.
What does 4/4 lumber mean?
4/4 means four-quarter inches, or 1 inch rough thickness. 8/4 is 2 inches, 12/4 is 3 inches. Hardwood is sold and measured at rough thickness even after surfacing removes material. A 4/4 board surfaced to 13/16 inch is still priced as 1 inch thick.
How many board feet in a cord of firewood?
A full cord is 128 cubic feet of stacked wood, which equals roughly 1,280 board feet if the wood were solid lumber — but firewood is sold by the cord, not the board foot. For lumber calculations, stick to the formula: thickness × width × length ÷ 12.
How much does a board foot of oak cost?
Red oak rough 4/4 typically runs $6 to $10 per board foot at a hardwood dealer. White oak runs $8 to $14. Wide boards over 8 inches and thicker stock at 8/4 or 12/4 command premiums of 20 to 50% above standard 4/4 pricing.
How many board feet in a 2x10x16?
A 2×10×16 contains 26.67 board feet (2 × 10 × 16 ÷ 12). At $1.50 per board foot for construction-grade SPF, that single joist costs about $40. A deck frame using twenty 2×10×16 joists needs 533 board feet of joist material alone.
What is the difference between board feet and linear feet?
Linear feet is length only — a 2×4×8 and a 2×12×8 are both 8 linear feet. Board feet accounts for cross-section: the 2×4 is 5.33 board feet and the 2×12 is 16 board feet. Hardwood is priced in board feet; trim and molding are often priced in linear feet.
How many board feet for a dining table top?
A 3-foot by 6-foot table top in 8/4 (2-inch) hardwood: 2 × 36 × 72 ÷ 12 = 432 board feet if made from a single slab — but most tops are glued from strips. Four strips 6 inches wide: 2 × 6 × 72 ÷ 12 × 4 strips = 288 board feet before waste.
How do you convert board feet to cubic feet?
Divide board feet by 12 to get cubic feet. One hundred board feet equals 8.33 cubic feet. A cord of firewood at 128 cubic feet equals about 1,536 board feet of solid wood volume, though stacked firewood includes air gaps.
How many board feet in a 4x4x8 post?
A 4×4×8 post contains 10.67 board feet (4 × 4 × 8 ÷ 12). Pressure-treated 4×4 posts are sold individually by the piece rather than by the board foot, but the calculation is the same when estimating material for a pergola or deck railing system.

You may also need

The next decision usually follows directly from this one.

Related trades

Where to go next