PCB Panelization Calculator: Boards per Panel and Utilization
Panelization decides how many boards you get from each fabrication panel, how well the SMT line runs, and what a bare board really costs. This calculator checks both board orientations on a standard panel and reports boards per panel, utilization and panels needed.
Your numbers
Finished board outline width.
Finished board outline length.
18 in is about 457 mm.
24 in is about 610 mm.
Fab tooling border plus assembly rail on each side.
Fab tooling border plus assembly rail on each side.
Router width and tab space; use 0 for V-score.
Your results
Grid layout only. Your fabricator's panel utilization rules, coupon needs and assembly rail design take precedence.
Boards per panel vs gap between boards
Sweeps Gap between boards from 0 to 10, holding your other inputs fixed.
Link panel yield to your item master
An optional review of how to pull array size, scrap and board cost from your ERP into one read-only view.
Optional. The tool and every export work without this. No spam.
How to use the calculator
Enter the finished board outline, the raw panel size your fabricator quotes (18 x 24 inch is the common stock size) and the unusable border on each side. The border covers the fab tooling strip and the rails your assembler needs for conveyor transport and fiducials. Then enter the gap between boards: about 2 to 3 mm for tab-route with a 2 mm router, or zero for V-score. The tool shows the grid count for both orientations and keeps the better one.
- Use the fabricator's usable area if they publish it
- Add a separate allowance if you need test coupons on the panel
- Check the assembly rail width against your SMT line's conveyor edge clearance
The formula behind it
Boards across = floor((usable width + gap) / (board width + gap)), and the same along the length. The gap is added to both sides of the division because the last board in a row has no trailing gap. The rotated case swaps the board dimensions. Utilization is the board area times the count divided by the whole panel area, so the borders and gaps appear as lost material. The chart sweeps the gap to show how a few tenths of a millimetre can drop an entire row.
Reading the result and common mistakes
Utilization above 80 percent is good for small boards and hard to reach for large ones. Remember that a fab panel is not the same as the assembly array: you often cut a fab panel into several assembly arrays with their own rails. Typical errors are forgetting the router diameter in the gap, using the nominal panel size instead of the usable size, and ignoring grain direction or copper balance requirements for thin laminates. Always have the fabricator confirm the final panel drawing.
Frequently Asked Questions
What is the standard PCB panel size?
Many fabricators work from 18 x 24 inch (about 457 x 610 mm) raw panels, with 12 x 18 and 21 x 24 also common. The usable area is smaller after the tooling border, so ask your fabricator for their exact numbers before you design the array.
How much gap should I leave between boards?
For tab-route panels, plan on the router diameter, commonly about 2 mm, plus any tab features. For V-score the gap is essentially zero because the boards touch along the score line. Check your fabricator's design rules for minimum spacing.
Should I rotate boards on the panel?
Rotating is allowed if your assembly process and fiducial scheme can handle it, but most arrays keep one orientation per panel. The calculator shows both so you can see whether rotation is worth a layout change.
Why is my assembler's array different from the fab panel?
The assembler's array is sized for the SMT conveyor and stencil frame, often much smaller than a raw fab panel. The fabricator routes several arrays out of one panel, so utilization is calculated at the fab panel level and the array is a separate design choice.
If you want panel yield, array size and board cost pulled from your ERP item and routing data instead of retyped, Netray can build that as a read-only view over your system.
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