CarpentryInstant Tool
Board Foot Calculator
Calculate lumber board feet, linear feet, total volume, and hardwood timber costs accurately.
Board Foot Estimator
Calculate board feet volume, total cost, and hardwood lumber board measure
How Board Foot Calculator Works
Board Feet FBM = Thickness in inches × Width in inches × Length in feet ÷ 12A board foot FBM is a specialized unit of lumber volume representing a piece of wood 1 inch thick, 12 inches wide, and 1 foot long equaling 144 cubic inches. When lumber length is measured in inches, divide total cubic inches by 144. When length is measured in feet, divide by 12.
Variable Breakdown
T
ThicknessNominal or rough sawn lumber thickness in inches
W
WidthLumber width in inches
L
LengthLumber length in feet or inches
Qty
Piece QuantityTotal number of identical lumber boards
Example Calculation
Hardwood Walnut Tabletop Lumber Order
Six boards of 8/4 rough sawn black walnut, each 2 inches thick, 8 inches wide, and 10 feet long, priced at $12.50 per board foot.
- Calculate board feet per board = 2 inches × 8 inches × 10 feet ÷ 12
- Board feet per board = 160 ÷ 12 = 13.33 FBM
- Total board feet for 6 boards = 13.33 × 6 = 80.0 FBM
- Total lumber cost = 80.0 × $12.50 = $1,000.00
Result:Total lumber volume is 80 Board Feet with a material cost of $1,000.00
Quarter Lumber Sizing and Rough Sawn Equivalents
| Lumber Quarter Sizing | Nominal Thickness | Surfaced S2S Thickness | Cubic Inches per Linear Ft 6 In Wide |
|---|---|---|---|
| 4/4 Four Quarter | 1.00 inch | 0.75 inch | 72 cu in |
| 5/4 Five Quarter | 1.25 inches | 1.06 inches | 90 cu in |
| 6/4 Six Quarter | 1.50 inches | 1.31 inches | 108 cu in |
| 8/4 Eight Quarter | 2.00 inches | 1.75 inches | 144 cu in |
| 12/4 Twelve Quarter | 3.00 inches | 2.75 inches | 216 cu in |
Frequently Asked Questions
What is a board foot in lumber?
A board foot FBM is a unit of volume measurement equal to a board 1 inch thick, 12 inches wide, and 1 foot 12 inches long, totaling 144 cubic inches of lumber.
How do I calculate board feet if length is in inches?
Multiply thickness in inches by width in inches by length in inches, then divide the resulting number by 144.
What does 4/4 and 8/4 mean in hardwood lumber?
Hardwoods are traditionally sold in quarter-inch increments of rough sawn thickness. 4/4 is four-quarters of an inch or 1 inch thick. 8/4 is eight-quarters of an inch or 2 inches thick.
What is the difference between linear feet and board feet?
Linear feet measures only the length of a board regardless of width or thickness. Board feet measures total 3-dimensional wood volume.
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