How many boards for a 24 inch panel?
Four nominal 6" boards make 24" only if their edges lose nothing to the jointer. Lose a sixteenth apiece and it takes five. Board counts for every panel width.
A 24" panel from 6" boards takes 5 of them, once each edge loses 1/16".
Each board actually contributes 5 15/16", so the glue-up comes out 29 11/16" wide and 5 11/16" gets ripped off to reach 24".
How that is worked out
- Jointing an edge takes material off it. At 1/16" per board, a 6" board contributes 5 15/16" to the panel.
- 24" ÷ 5 15/16" = 4.04, rounded up to 5 boards.
- With perfectly clean edges it would be 4. The last board only just crosses the line, which is exactly the case that catches people out mid-glue-up.
Boards needed, losing 1/16" off each one to jointing
| Panel width | 4" boards | 6" boards | 8" boards | 10" boards |
|---|---|---|---|---|
| 12" | 4 | 3 | 2 | 2 |
| 16" | 5 | 3 | 3 | 2 |
| 20" | 6 | 4 | 3 | 3 |
| 24" | 7 | 5 | 4 | 3 |
| 30" | 8 | 6 | 4 | 4 |
| 36" | 10 | 7 | 5 | 4 |
| 48" | 13 | 9 | 7 | 5 |
Worth knowing
- Always glue up wider than the finished panel and rip it to size afterwards. The outside edges are where the clamps bruise the wood and where the glue-up is least likely to be straight.
- How much an edge loses depends on how bowed the board was. A straight board loses almost nothing; a board with a bow along its length loses whatever it takes to make it straight, which can be an eighth or more.
- Alternating the growth rings board to board is the traditional advice and it is not wrong, but on a well-supported panel matching the grain for looks usually matters more. Both faces finished equally does more to keep a panel flat than either.
- Narrower boards make a more stable panel and more glue lines. Wider ones look better and move more. Four to six inches is the usual compromise.
- When the last board is mostly going to be ripped away — as it is here, where five boards give nearly 30" for a 24" panel — rip it to width before glue-up rather than after. A narrower board in the middle of the panel looks deliberate; five inches trimmed off one edge afterwards looks like what it is.
Work out your own numbers
- Panel glue-up calculator
How many boards it takes to glue up a target panel width, and how much wider to glue up so the rip lands clean.
- Board foot calculator
How much lumber to buy for a finished piece, what it will cost, and what to ask for at the yard.
- Pocket hole screw calculator
Screw length and thread by material thickness, and how far apart to space the holes along an edge joint.
Related questions
- How many boards do I need for a 24 inch table top?
- Five nominal 6" boards, not four, once each one loses about a sixteenth to jointing. Four is the answer people plan on and it leaves you a quarter inch short with the glue already open. Work it from what each board actually contributes after its edges are cleaned up.
- How much wider should a glue-up be than the finished panel?
- An inch or so on the width and a couple of inches on the length. The outer edges take the clamp marks and are the least likely to be dead straight, and trimming them off is much easier than trying to get them perfect in the clamps.
- Do I need to alternate the grain direction when gluing up a panel?
- It is traditional and it does limit how much any one cup can add up across the panel, but it is far less important than people say. Matching the boards for appearance usually produces a better piece, and finishing both faces equally does more for flatness than ring orientation ever will.