Board Foot Calculator
Total board feet and cost for a cutlist, plus a log scale for rough logs.
Cutlist — add every piece of lumber, board feet total updates as you type.
Board feet from a log (Doyle scale)
Estimated board feet
How board footage is calculated
A board foot is a unit of lumber volume equal to a piece 12" long, 12" wide and 1" thick — 144 cubic inches. It's the standard way hardwood and specialty lumber is priced, since boards come in irregular widths and thicknesses.
The formula for one piece is:
board feet = (thickness in × width in × length in) / 144
Worked example: a board that is 4/4 (1" thick), 6" wide and 8 ft (96") long: (1 × 6 × 96) / 144 = 4.0 board feet. Buy three of those and your cutlist total is 12 board feet. At $6.50 per board foot that's $78.00 before waste.
Rough-sawn hardwood is almost always sold in quarter thickness notation: 4/4 means four quarters of an inch (1"), 5/4 is 1¼", 6/4 is 1½" and 8/4 is a full 2". The thickness dropdown above has these built in — pick "Custom" to enter any exact thickness, which is useful once a board has been planed down (S4S lumber typically loses about ⅛"–¼" from its nominal size).
Estimating board feet in a standing log
Sawmills and loggers commonly use the Doyle log scale to estimate how much lumber a log will yield once sawn:
BF = ((diameter − 4) / 4)² × length
Diameter is measured inside the bark at the small end of the log in inches, and length is in feet. For a 16" diameter log that's 12 ft long: ((16 − 4) / 4)² × 12 = 3² × 12 = 108 board feet. Doyle is conservative and undercounts small-diameter logs — the Scribner and International ¼" scales tend to run higher — so treat this as a rough estimate, not a mill-accurate tally.
Practical tip: always add 10–15% to your cutlist total to cover defects, saw kerf, and mistakes, and buy full boards rather than the exact fractional board footage since most yards don't sell partial pieces.
Board Foot Calculator: frequently asked questions
How do you calculate board feet?
Board feet = (thickness in inches × width in inches × length in inches) ÷ 144. One board foot is a piece of wood 12" × 12" × 1" thick.
What does 4/4, 5/4 or 8/4 mean for lumber thickness?
Rough-sawn hardwood is sold by quarters of an inch. 4/4 ("four quarter") is 1" thick, 5/4 is 1.25", 6/4 is 1.5" and 8/4 is 2". Use the quarter buttons to fill the thickness field automatically.
Is board footage based on nominal or actual size?
This calculator uses whatever dimensions you enter. Rough lumber is usually priced and measured at nominal (rough-sawn) size before planing, while dressed (S4S) boards run about 1/8" to 1/4" under nominal — enter actual measured dimensions for the most accurate total.
How do I estimate board feet in a log?
Use the Doyle log scale: BF = ((diameter − 4) ÷ 4)² × length, where diameter is the small-end diameter inside the bark in inches and length is in feet. Doyle tends to underestimate yield on small logs and is most accurate for logs 20" and up.
Do I need to round up board feet when buying lumber?
Most yards sell to the nearest board foot or invoice by the piece, so round each piece up and add 10–15% extra for defects, milling waste and mistakes when pricing a project.