Gerber File Guide: KiCad, Eagle & Altium

Exporting correct Gerber files from KiCad, Eagle, and Altium is the critical step between PCB design and manufacturing. An incorrectly exported Gerber set results in manufacturing errors, delayed production, or boards that do not match your design. This guide provides step-by-step export instructions for the three most popular PCB design tools, along with a verification checklist to catch errors before submitting to the manufacturer.

What Are Gerber Files
Required Files for Manufacturing
Exporting from KiCad
Exporting from Eagle
Exporting from Altium Designer
Gerber Verification Checklist
Frequently Asked Questions
Conclusion

What Are Gerber Files

Gerber files are the universal file format for PCB manufacturing, analogous to PDF for documents. Each Gerber file describes one layer of the PCB using vector graphics. A complete set includes separate files for the top copper layer, bottom copper layer, top and bottom solder mask, top and bottom silkscreen, board outline, and drill file (Excellon format). Together, these files contain all the information a manufacturer needs to produce your PCB.

Required Files for Manufacturing

A standard 2-layer PCB requires a minimum of 8 files. The copper layers (F.Cu and B.Cu) define the electrical traces. The solder mask layers (F.Mask and B.Mask) define where the green coating is removed for soldering. The silkscreen layers (F.SilkS and B.SilkS) define component labels and markings. The edge cuts layer defines the board outline and any cutouts. The drill file (Excellon format) defines all hole positions and sizes. Missing any of these files causes manufacturing issues.

Exporting from KiCad

In KiCad’s PCB editor, go to File, then Plot. In the Plot dialog, select Gerber as the format. Check the following layers: F.Cu, B.Cu, F.SilkS, B.SilkS, F.Mask, B.Mask, Edge.Cuts, and F.Paste and B.Paste if ordering a stencil. Set the output directory to a dedicated folder (for example, “gerber”). Click Plot to generate the Gerber files. Then click “Generate Drill Files” to create the Excellon drill file in the same directory. Set drill units to millimetres and format to Excellon. Ensure “PTH and NPTH in single file” is selected unless your manufacturer requires separate files.

Exporting from Eagle

In Eagle’s board editor, go to File, then CAM Processor. Use the built-in “gerb274x.cam” job file which generates all required layers automatically. Alternatively, create a custom CAM job selecting: Top (layer 1), Bottom (layer 16), tStop and bStop (solder mask), tPlace and bPlace (silkscreen), Dimension (board outline), and Drills. Set the device to GERBER_RS274X for copper and mask layers and EXCELLON for the drill file. Click Process Job to generate all files.

Exporting from Altium Designer

In Altium, go to File, then Fabrication Outputs, then Gerber Files. In the Gerber Setup dialog, add all required layers using the Layers tab. Set the format to RS-274X (the modern Gerber standard). Set units to millimetres and format to 4:6 (integer:decimal places) for maximum precision. Click OK to generate. Then go to File, then Fabrication Outputs, then NC Drill Files to generate the drill file separately. Ensure the drill file uses the same coordinate origin as the Gerber files.

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Gerber Verification Checklist

Before sending Gerber files to a manufacturer, verify them using a Gerber viewer. Free options include KiCad’s GerbView and the online viewer at gerber-viewer.com. Check that the board outline is a closed shape with no gaps. Verify that all copper traces are present and correctly connected. Confirm solder mask openings align with pads. Check silkscreen text is readable and does not overlap pads. Verify drill holes are present at all through-hole component locations and vias. Ensure there are no stray traces or artifacts from the design process.

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Frequently Asked Questions

Should I use Gerber RS-274X or Gerber X2?

Use Gerber RS-274X for maximum compatibility. While Gerber X2 adds metadata (layer types, stack-up information), not all manufacturers support it yet. RS-274X is universally accepted by every PCB manufacturer worldwide.

Do I need to include a BOM or assembly drawing?

For bare PCB manufacturing, Gerber and drill files are sufficient. For PCB assembly (PCBA) services, additionally provide a Bill of Materials (BOM) in Excel/CSV format and a component placement file (pick and place file) for automated assembly.

My manufacturer says the drill file is missing. What happened?

The drill file is generated separately from Gerber files in most software. It uses the Excellon format (not Gerber) and has a .drl or .xln extension. Re-export specifically the drill/NC drill output and include it with your Gerber package.

Conclusion

Correct Gerber file export is a straightforward process once you know the required layers and settings for your design tool. Follow the tool-specific steps in this guide, verify with a Gerber viewer before submitting, and you will avoid the costly delays of manufacturing errors. Bookmark this guide as a reference for every PCB project.

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