Guides
Pallet deck board spacing: how to calculate the gaps
Reviewed
With lead boards flush at both ends and interior boards equally spaced, the gap between pallet deckboards is (pallet length minus the total width of all boards) divided by (number of boards minus 1). A 48 x 40 GMA-style top deck with two 5-1/2 in lead boards and five 3-1/2 in interior boards has (48 - 28.5) / 6 = 3.25 in gaps and about 59% deck coverage.
On this page
Deckboard spacing decides how well the top deck supports the load, how much lumber the pallet uses, and whether forks and pallet-jack wheels can get in underneath. It is also the easiest dimension to calculate exactly.
The spacing formula
The usual rule is ends flush, interior boards equally spaced: the two lead boards sit flush with the pallet ends and every gap between boards is the same.
gap = (L - sum of board widths) / (n - 1)
where L is the pallet length (the stringer length) and n is the number of boards.
Worked example: 48 x 40 GMA-style top deck
- 2 lead boards x 5-1/2 in = 11 in
- 5 interior boards x 3-1/2 in = 17.5 in
- Total board width = 28.5 in
- Gap = (48 - 28.5) / (7 - 1) = 19.5 / 6 = 3.25 in
Leading-edge positions from one end are cumulative: 0, 8.75, 15.50, 22.25, 29.00, 35.75, 42.50 in. The last board ends at 42.50 + 5.50 = 48.00, flush.
Deck coverage is total board width divided by length: 28.5 / 48 = 59%.
Adding a board
Add an eighth board (a sixth interior board) and the gap becomes (48 - 32) / 7 = 2.29 in, with 67% coverage. Every extra board adds lumber and nails, so the right count is the fewest boards that support the load.
Bottom deck spacing and the interior cluster
On a notched stringer pallet, bottom boards must not sit under the notches, or forks entering from the side hit them. So the bottom deck uses an interior cluster: lead boards flush at the ends, interior boards grouped in the middle between the notches.
On the GMA-style pallet the notches run from 6 to 15 in from each end. The bottom deck has two 5-1/2 in leads and three 3-1/2 in interior boards at 15.00, 22.25 and 29.50 in, with 3.75 in gaps between them and 9.50 in openings from 5.50 to 15.00 in over each notch.
On an unnotched (two-way) pallet the bottom boards can be spaced evenly with the same formula as the top.
How big should deckboard gaps be?
There is no single rule; it depends on the load.
| Load | Gap guidance |
|---|---|
| Large cartons, uniform loads | 3 to 4 in gaps are common (GMA: 3.25 in) |
| Small cartons, bags | Tighter gaps so packages bridge several boards |
| Drums, pails, point loads | Keep gaps under about 2.5 in so chimes and feet cannot drop in |
| Loose or small items | Solid deck (no gaps) or a panel deck |
palletdesign.ai warns when top-deck gaps exceed 5 in, where cartons and bags start to sag through, and when drum or point loads sit on gaps over 2.5 in.
Cartons carry most of their compression strength at their corners and walls. If a gap falls under a carton wall, that wall loses support. For heavy boxed loads, check where the box walls land on the deck, not just the gap size.
Worked example: 42 x 42 with tighter gaps
A 42 x 42 with 7 top boards (2 x 5-1/2 in leads, 5 x 3-1/2 in interior) has a total board width of 28.5 in and a gap of (42 - 28.5) / 6 = 2.25 in, with 68% coverage. Same boards, shorter span, tighter deck.
Deck coverage and cost
Deck coverage trades support against lumber. The top deck of the GMA-style pallet is about 4.9 of its 13.5 board feet. Going from 7 to 9 top boards on a 48 in deck adds about 1.2 board feet and 12 nails (two more boards, 2 nails each on 3 stringers).
Special layouts
- Butted boards: two boards set tight against each other, usually beside a lead board. The Uniform Standard treats two butted 4 in boards as equal to one 6 in board. See butted boards.
- Solid deck: no gaps, for small or loose items.
- Custom spacing: any layout, for example tight gaps at the ends where the load's edges sit.
Worked example: a 48 x 48 drum deck
Four 55-gal drums on a 48 x 48 need gaps well under 2.5 in. With 9 top boards (two 5-1/2 in leads and seven 3-1/2 in interior boards) the boards total 35.5 in, and the gap is (48 - 35.5) / 8 = 1.56 in, with 74% coverage. Seven boards of the same widths would leave (48 - 28.5) / 6 = 3.25 in gaps, too wide for drum chimes.
Checking spacing on a quote
When a mill sends a drawing, recompute the gap from the board count and widths. If the boards are narrower than you specified (the Uniform Standard allows deckboards up to 1/4 in under width), the gaps grow: seven boards each 1/4 in narrow add 1.75 in of open deck, about 0.29 in per gap on a GMA-style top.
Placement tolerance
The Uniform Standard allows lead boards to be within 1/4 in of their specified location and other components within 1/2 in (with limits on how many may deviate). A spacing that works on paper must still work at those tolerances. See pallet tolerances.
Questions
- What is the standard gap between pallet boards?
- There is no single standard. A GMA-style 48 x 40 with 7 top boards has 3.25 in gaps. Drum and point loads need gaps under about 2.5 in; small or loose items need a solid deck.
- How do you calculate pallet board spacing?
- Subtract the total width of all boards from the pallet length and divide by the number of gaps (boards minus one). For 7 boards totaling 28.5 in on a 48 in pallet: (48 - 28.5) / 6 = 3.25 in.
- Why are bottom boards grouped in the middle?
- On notched stringer pallets the bottom interior boards are clustered between the notches so they don't block forks entering from the side.
- What is deck coverage?
- The percentage of the deck length covered by boards. A 48 in deck with 28.5 in of boards has about 59% coverage.