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Free board foot calculator

Board Foot Calculator

Add up board feet and cost for a lumber list, or estimate the board feet in a log.

    Thickness can be quarters: 4/4, 5/4, 8/4.

    How to use the board foot calculator

    1. For each size, enter thickness and width in inches, length in feet and how many pieces.
    2. Press Add a size for more lines; add a price per board foot for the total cost.
    3. For standing timber or logs, switch to Logs and enter the small-end diameter and length.

    The board foot formula

    Board feet = thickness (in) × width (in) × length (ft) ÷ 12

    Or with every dimension in inches: thickness × width × length ÷ 144. Ten 2×4s at 8 ft are 2 × 4 × 8 ÷ 12 × 10 = 53.3 board feet. The board feet guide has more worked examples.

    Log scale rules

    Doyle = (D − 4)² ÷ 16 × L

    D is the small-end diameter inside the bark in inches and L the length in feet. Scribner uses the formula (0.79D² − 2D − 4) × L ÷ 16, and the International ¼" rule adds up 4-ft sections with ½" of taper each. Mills and timber sales say which rule they use — they can differ by 30% or more on small logs.

    Frequently asked questions

    How do I calculate board feet?

    Multiply thickness (inches) × width (inches) × length (feet) and divide by 12. A 2×6 that is 10 ft long is 2 × 6 × 10 ÷ 12 = 10 board feet.

    What is a board foot?

    A volume of wood 1" thick, 12" wide and 12" long — 144 cubic inches, or 1/12 of a cubic foot. Hardwood and rough lumber are priced per board foot.

    Do I use nominal or actual size?

    Lumberyards use nominal size for dimensional lumber (a 2×4 counts as 2" × 4") and the rough, pre-planed thickness for hardwood (4/4 = 1"). Enter the sizes your yard prices by.

    What does 4/4, 5/4 or 8/4 mean?

    Hardwood thickness in quarter inches: 4/4 is 1", 5/4 is 1 1/4", 8/4 is 2". You can type them straight into the thickness box.

    How many board feet are in a log?

    It depends on the log rule. For a 16" × 12 ft log: Doyle gives 108 board feet, Scribner about 125 and International ¼" about 131. Doyle under-counts small logs; International is closest to what a sawmill recovers.

    How do I work out the cost?

    Multiply the total board feet by the price per board foot. Enter the price in the calculator and it shows the total cost of your lumber list.