Board Foot Calculator

What Is a Board Foot?

A board foot is the standard unit for measuring and pricing hardwood lumber in North America. One board foot equals a piece of wood 1 inch thick, 12 inches wide, and 12 inches long, which is 144 cubic inches of wood. Unlike dimensional softwood lumber sold by the linear foot (2x4s, 2x6s), hardwoods like oak, walnut, cherry, and maple are sold by the board foot. The calculator above converts your lumber dimensions into board feet and optionally estimates the total cost based on price per board foot.

How to Calculate Board Feet?

The formula is: Board Feet = (Thickness in inches x Width in inches x Length in feet) / 12. A board that is 1 inch thick, 6 inches wide, and 8 feet long contains (1 x 6 x 8) / 12 = 4 board feet. A 2-inch thick plank that is 10 inches wide and 12 feet long contains (2 x 10 x 12) / 12 = 20 board feet. When buying multiple pieces, calculate the board footage of each piece and add them together for the total.

Why Is Lumber Sold by the Board Foot?

Hardwood lumber comes in random widths and lengths because each tree is different. A sawmill cuts boards to maximize yield from each log, producing pieces of varying dimensions. Selling by the board foot standardizes pricing regardless of the board size. A narrow 4-inch wide board and a wide 12-inch board of the same species and grade cost the same per board foot. This system allows sawmills to sell their entire production without sorting into fixed sizes and lets buyers compare prices fairly across different suppliers and dimensions.

What Are Nominal vs Actual Lumber Dimensions?

Hardwood lumber is measured at its rough-sawn thickness before surfacing. A board sold as 4/4 (four-quarter) is 1 inch thick rough, which surfaces to approximately 13/16 inch after planing. 5/4 stock is 1.25 inches rough. 6/4 is 1.5 inches rough. 8/4 is 2 inches rough. Board foot calculations use the nominal (rough) thickness, not the surfaced thickness. If you buy 100 board feet of 4/4 lumber, you are paying for wood that was 1 inch thick before planing, even though the finished pieces will be thinner.

How Much Does Hardwood Lumber Cost Per Board Foot?

Prices vary by species, grade, and region. Poplar runs $3-$5 per board foot and is one of the most affordable hardwoods. Red oak costs $4-$7. White oak is $5-$9. Hard maple ranges from $5-$8. Cherry costs $6-$10. Black walnut runs $8-$15 or more for premium grades. Exotic species like mahogany, teak, and purpleheart can exceed $15-$25 per board foot. Lumber grades (FAS, Select, #1 Common, #2 Common) also affect price, with FAS (First and Seconds) being the highest quality and most expensive.

How to Convert Board Feet to Other Units?

One board foot equals 1/12 of a cubic foot. Multiply board feet by 0.00236 to get cubic meters. To convert linear feet of a known dimension into board feet: multiply the linear footage by the thickness (inches) and width (inches), then divide by 12. Going the other direction, divide total board feet by the per-piece board footage to find how many pieces you can get from a given quantity of lumber.

Board Feet for Common Woodworking Projects

A simple cutting board uses 2-3 board feet. A small bookshelf needs 15-25 board feet. A dining table for six requires 30-50 board feet for the top plus 10-15 for the base. A set of kitchen cabinets can consume 100-200 board feet. A queen-size bed frame uses 40-60 board feet. These estimates assume typical designs and include some waste for defects, jointing, and planing. Actual consumption depends on your design, the lumber grade (lower grades have more waste), and how efficiently you lay out your cuts.

Tips for Buying Hardwood Lumber

Buy from a reputable hardwood dealer rather than a big-box store for better selection and lower prices per board foot. Inspect boards for straightness, checking for twist, bow, and cup. Look at the end grain to assess drying quality and predict movement. Buy 15-20% more than your calculated need to account for defects, saw kerf, and mistakes. Let lumber acclimate in your shop for at least a week before milling to allow it to reach equilibrium moisture content with your working environment. Rushing this step leads to warping after assembly.

Frequently asked questions