A Gerber file is the standard format manufacturers use to turn your circuit board design into physical production

When an electronics designer finishes laying out a circuit board in software, they export it as a Gerber file — a set of image files that describe exactly where every copper trace, hole, and component should go. Think of it like sending a blueprint to a printer, except the printer is a machine that etches copper onto fiberglass. The Gerber format has been the industry standard since the 1980s because it works the same way across every PCB manufacturer in the world.

A Gerber file is not a single document. It is a collection of files, usually zipped together, where each file represents one layer of the board. One file shows where the copper goes on the top layer, another shows the bottom layer, another shows where holes need to be drilled, and so on. The manufacturer reads these files into their production equipment, which then cuts, etches, and assembles the board according to those exact specifications.

Key Takeaways

  • A Gerber file is a set of image files exported from circuit board design software that tells manufacturers exactly how to produce a PCB.
  • Each Gerber file represents one layer of the board — copper traces, solder mask, silkscreen, drill holes — so a complete set contains multiple files.
  • The format has remained unchanged for decades, which is why every PCB manufacturer worldwide can read and produce from the same files.
  • You generate Gerber files from design software like KiCad, Altium, or Eagle by using the export or "plot" function, not by hand.

How Gerber files are structured

A typical Gerber export for a simple two-sided board includes at least four files. The top copper layer file shows all the copper traces and pads on the top side where components sit. The bottom copper layer file shows the same for the underside. A drill file tells the machine where to drill holes for component leads and vias — the small holes that connect layers. A solder mask file defines which areas should be coated with the green (or other color) insulating layer that prevents solder from bridging between traces.

More complex boards add more files. A silkscreen file shows where text and symbols should be printed on the board surface — usually component labels and reference designators. Some boards include a paste mask file for automated assembly, which tells the pick-and-place machine where to deposit solder paste. A profile or outline file defines the physical edge of the board so the machine knows where to cut.

Each file is a 2D image in a format called RS-274X, which is the formal name for the Gerber standard. The files are text-based but contain coordinate data and drawing commands rather than readable words. Design software converts your visual layout into these coordinates automatically when you export.

Why manufacturers need Gerber files instead of design files

You might wonder why you cannot just send the original design file from KiCad or Altium directly to the manufacturer. The reason is that design software is meant for editing and thinking about circuits, not for manufacturing. A design file contains information a factory does not need — component libraries, schematic links, design rules, undo history — and lacks information the factory does need in a format the factory equipment can read.

Gerber files are stripped down to pure manufacturing data: coordinates, line widths, and layer information. This standardization means a manufacturer in China, Taiwan, or the United States can read the exact same Gerber files without needing to own or understand your design software. It also prevents accidental changes — once you export a Gerber, the design is locked. The manufacturer cannot accidentally move a trace or change a trace width because the file format does not allow editing.

How to generate Gerber files from your design

In KiCad, open your board file and go to File > Plot. A dialog box appears where you select which layers to export — typically you check "F.Cu" (front copper), "B.Cu" (back copper), "F.Mask" (front solder mask), "B.Mask" (back solder mask), "F.SilkS" (front silkscreen), and "Edge.Cuts" (board outline). Set the plot format to Gerber and choose an output folder. Click Plot, and KiCad generates one .gbr file for each layer you selected.

In Altium, the process is similar: File > Fabrication Outputs > Gerber Files. You select which layers to include and Altium generates the files. In Eagle, use File > CAM Processor and load one of the pre-built Gerber job files that come with the software, then run it against your board.

After generating the files, most designers also generate a drill file (usually a .txt or .xln file) and a netlist or bill of materials (BOM) so the manufacturer knows what components go where. Some manufacturers also ask for a Gerber preview — a PDF or image showing what the board will look like — so you can catch mistakes before production starts.

Common mistakes when exporting Gerber files

The most frequent error is forgetting to include all necessary layers. If you forget the solder mask file, the manufacturer will coat the entire board in mask, covering the pads where components solder. If you forget the silkscreen, your board ships without any labels. Always check the manufacturer's requirements before exporting — they usually publish a checklist of which files they need.

Another common mistake is exporting at the wrong scale or units. Gerber files can be in inches or millimeters, and if your design software and the manufacturer's equipment disagree on units, the board comes out the wrong size. Most modern software handles this correctly by default, but it is worth confirming in the export dialog.

A third mistake is including design layers that should not go to manufacturing — like dimension lines, notes, or reference grids. These can confuse the manufacturer's equipment or add unwanted marks to the board. Most software lets you control which layers export, so disable anything that is not a physical layer.

What happens after you send Gerber files to a manufacturer

When you upload Gerber files to a PCB manufacturer's website, their software reads them and generates a visual preview so you can see what the board will look like. This is your chance to catch mistakes — if a trace looks too thin, a hole is in the wrong place, or a layer is missing, you see it here before production starts. Most manufacturers let you download a PDF preview and check it against your original design.

Once you approve, the manufacturer loads the Gerber files into their production equipment. A machine called a photoplotter uses the Gerber data to expose a photoresist layer on the copper, which is then etched away to leave the traces. For multi-layer boards, this process repeats for each layer, and the layers are laminated together. Holes are drilled according to the drill file, the solder mask is applied, and silkscreen is printed.

Gerber files and design software you might use

KiCad is free and open-source, and generates clean, standard Gerber files that every manufacturer accepts. Altium Designer is professional-grade software used by large companies and produces Gerber files with advanced options for controlled impedance and high-speed design. Eagle (now part of Autodesk) is popular for hobbyists and small businesses and has built-in Gerber export.

EasyEDA is a browser-based tool that lets you design and order boards without leaving the website — it generates Gerber files automatically and sends them to their manufacturing partner. Fritzing is simpler and more visual, aimed at beginners, though its Gerber export is less feature-rich than professional tools.

Regardless of which software you use, the Gerber files it produces follow the same standard, so any manufacturer can read them. The differences are in how much control each tool gives you over advanced manufacturing options like trace width, layer stackup, and impedance.

Frequently Asked Questions

Can I edit a Gerber file after I export it?

Technically yes, but you should not. Gerber files are text-based, so you can open one in a text editor and see the coordinates and commands. However, editing by hand is error-prone and defeats the purpose of using design software. If you need to change something, go back to your design software, make the change, and export a new Gerber file.

What if the manufacturer says my Gerber files are invalid?

This usually means a layer is missing, the scale is wrong, or the file was corrupted during upload. Download the files again from your design software, double-check that you included all required layers, and re-upload. If the problem persists, contact the manufacturer's support — they can often tell you which file is causing the issue.

Do I need to send the original design file to the manufacturer?

No. Gerber files are all a manufacturer needs to produce your board. Sending the original design file (like a .kicad_pcb or .brd file) is unnecessary and does not help. The manufacturer works only from Gerber files.

Why is it called a Gerber file?

The format was created by Gerber Systems Corporation in the 1980s for their photoplotter machines. The name stuck even though many manufacturers now use different equipment. The formal standard is RS-274X, but everyone in the industry calls it Gerber.

Can different manufacturers read the same Gerber files?

Yes. That is the whole point of the standard. You can send the same Gerber files to manufacturers in different countries and get identical boards. This lets you compare prices and lead times without re-exporting or reformatting.