Updated · Built and checked by the PlinzoTools team, formulas tested against published sources
Calculate how many stock-length lumber pieces you need to cover a total linear-footage requirement.
28 x 8ft
This answers a different, more practical question than a pure volume calculation: given a total linear footage of lumber you need for a project (blocking, furring strips, a simple linear framing run), how many actual stock-length pieces do you need to buy? Lumber is sold in fixed stock lengths -- 8, 10, 12, and 16 feet are the most common -- so the number of pieces to buy always rounds up to a whole number, and cuts waste some material along the way.
Enter your total linear footage needed and pick the stock length you'll be buying. A cut-waste allowance (10% by default) accounts for material lost to trimming, mistakes, and offcuts too short to reuse.
Pieces = ROUNDUP((Total Linear Feet × (1 + Waste)) ÷ Stock Length)
Use this for framing blocking, furring strips, fence rails, or any project defined by a total run length rather than a single board's exact volume. For hardwood or specialty lumber priced by volume instead, see the Board Foot Calculator.
The calculator treats your requirement as one continuous run of lumber: it inflates the total by the waste percentage and divides by the stock length. That works well when many small pieces can be cut from long boards with little leftover, but it can under-count when your individual cuts are awkward lengths that do not divide evenly into a stock board.
Consider a hypothetical project needing 40 pieces that are each 35 inches long. That is 1,400 inches, or about 116.7 linear feet. With 10 percent waste and 8-foot boards the calculator gives ROUNDUP(128.3 / 8) = 17 boards. But an 8-foot board is 96 inches, so it yields only two 35-inch pieces (70 inches used, 26 inches left over). Forty pieces at two per board needs 20 boards, three more than the estimate. When your cut length is fixed, do a quick per-board check: divide the stock length by the cut length, round down, and use that yield to work out the true board count.
Pieces per board = FLOOR(Stock Length ÷ Cut Length)
Boards needed = ROUNDUP(Total Pieces ÷ Pieces per Board)
Suppose you are adding blocking between joists and the total run measures 150 linear feet. You choose 12-foot boards and keep the default 10 percent waste. The inflated need is 165 feet, and 165 / 12 = 13.75, so you buy 14 pieces. The extra 0.25 of a board beyond 13.75 is useful slack, since lumber yards sometimes hand over a few boards with defects such as bows, splits, or excessive knots that you will not want to use.
The result is a purchasing estimate, not a cut list. It does not account for saw kerf, defects you cut around, or structural requirements. For anything load-bearing, follow your plans or local building code rather than a generic quantity.
8, 10, 12, and 16 feet are the most common stock lengths for dimensional lumber at US lumber yards and home centers.
Because you can't buy a fraction of a board -- if your project needs 8.2 pieces' worth of lumber, you have to buy 9 whole pieces, so rounding up (not to the nearest) is the only realistic purchasing number.
The waste allowance already adds a cushion. If you know the lumber will be visible or you are working with warped stock, raising the waste to 15 percent is a reasonable choice.
Not in one pass. The calculation only knows total length and stock length, so run it once for each lumber dimension you plan to buy.
Very short cuts are efficient because offcuts are small, so the default waste is usually fine. The under-count risk is greatest for cuts just over half or a third of the stock length.
Each cut removes roughly an eighth of an inch. On a few cuts it is negligible, but on dozens of cuts it adds up, which is one reason to keep some waste in the estimate.