Construction & DIY · Woodworking
Panel glue-up board count calculator.
Enter the finished panel width and your board width to see how many boards to glue up and how much will be left to trim.
Inputs
Glue-up plan
Enter a panel width and board width.
How many boards do I need to glue up a tabletop?
The glued width of n boards is n × board width − (n − 1) × the material lost at each joint. This tool finds the smallest n whose glued width reaches the finished width plus the extra you want to trim. Using the equal board width it also shows lets you plane all the boards to the same width and land on the target with no leftover.
Worked example. For a 24 in top from 5.5 in boards, allowing 1/8 in lost per joint and 1/2 in to trim, you need a glued width of at least 24.5 in. Five boards give 5 × 5.5 − 4 × 0.125 = 27 in, which leaves 2.5 in to trim, or you can mill five boards to about 5.0 in each to reach 24.5 in.
Account for wood movement across the panel separately: a wide glued panel still swells and shrinks with humidity, as the wood movement calculator shows.
Frequently asked questions
How many boards do I need for a 24 inch wide tabletop?
With 5.5 in boards, 1/8 in lost per joint and 1/2 in to trim, five boards: 27 in glued width and 2.5 in to trim off.
How much width is lost when jointing edges for a glue-up?
It depends on how much each edge has to be cleaned up. The tool lets you enter your own figure per joint rather than assume one.
Should the boards all be the same width?
It is a layout choice. The tool shows the equal board width that gives the target exactly, or you can mix widths and check the total glued width.
Does this account for seasonal wood movement?
No. It sizes the panel at assembly. Use the wood movement calculator to see how much the finished width will change with humidity.
Sources
Checked
No published data table is used; this is arithmetic on the widths you enter, tested for the board-count rule, joint loss, trim and the equal-width result. Runs entirely in your browser. Nothing you type is sent or stored.
Scope
Layout arithmetic for woodworking. Mill and dry-fit the boards before gluing.