A Gerber file is the standard digital blueprint that tells manufacturing equipment how to build a circuit board
When an engineer designs a circuit board on a computer, they create the layout in design software. But the machines that actually manufacture the board cannot read that design file directly. A Gerber file is the translated version — a standardized format that CNC machines, laser cutters, and other manufacturing equipment understand. It contains the exact coordinates, dimensions, and instructions for every trace, hole, and component placement on the board.
The format has been the industry standard since the 1970s, when Gerber Systems Corporation created it. Today, nearly every circuit board manufacturer worldwide accepts Gerber files as the primary way designers hand off their work. If you have ever ordered a custom circuit board online, the manufacturer received your design as a Gerber file.
Think of it like the difference between a Word document and a PDF. The Word document is what the designer works in; the PDF is what gets sent to the printer because the printer's equipment knows exactly how to read it without any guessing about fonts, spacing, or colors.
Key Takeaways
- A Gerber file is a standardized digital format that manufacturing equipment uses to build circuit boards, created by translating a designer's layout into machine-readable instructions.
- The format includes information about copper traces, drill holes, solder masks, silkscreen labels, and component placement — everything the manufacturing machines need to know.
- Gerber files are named after Gerber Systems Corporation, which developed the format in the 1970s, and remain the industry standard across all circuit board manufacturers.
- Designers export Gerber files from their PCB design software and send them to manufacturers, who load them into their production equipment.
What information a Gerber file actually contains
A Gerber file is not a single document — it is a set of files, usually between 6 and 10, each describing a different layer of the circuit board. One file shows where the copper traces go on the top layer. Another shows the bottom layer. A third shows where holes need to be drilled. A fourth shows the solder mask, which is the colored coating that protects the copper and prevents solder from bridging between traces.
Additional files describe the silkscreen layer (the white or yellow text and symbols printed on the board), the component outline (where parts physically sit), and sometimes internal layers if the board has more than two sides. Each file uses a coordinate system to specify exact positions down to thousandths of an inch.
The files also contain aperture definitions — essentially a list of shapes and sizes the manufacturing equipment will use. For example, one aperture might be a 0.01-inch circular hole, another a 0.02-inch square pad. The equipment reads these definitions and then follows the coordinates to place each shape in the right location.
How designers create and export Gerber files
A circuit board designer uses specialized software like KiCad, Altium Designer, or Eagle to draw the layout. These programs let the designer place components, route copper traces between them, and set up the different layers. Once the design is complete and checked for errors, the designer exports it as Gerber files.
The export process is straightforward in most design software — usually a menu option called "Export Gerber" or "Generate Gerber." The software asks which layers to include and what resolution to use, then creates the file set. The designer then compresses these files into a ZIP folder and sends them to the manufacturer.
Before sending, designers typically run a design-rule check (DRC) to catch problems like traces that are too close together or vias in the wrong place. Some manufacturers also offer a free review service where they check the Gerber files for manufacturability before production starts.
Why manufacturers use Gerber instead of other formats
Gerber became the standard because it is straightforward, reliable, and works with any manufacturing equipment. Unlike proprietary design software formats, Gerber is an open standard that every machine maker supports. A designer in Japan can send Gerber files to a manufacturer in Taiwan or the United States, and the files will work identically on all their equipment.
The format is also compact and fast to process. A Gerber file for a complex board might be only a few megabytes, and the manufacturing equipment can parse and execute it in seconds. Newer formats exist — like ODB++ — but they are more complex and require specialized software, so most manufacturers still prefer Gerber for routine work.
Gerber's longevity also means that decades of manufacturing equipment still uses it. Replacing all that machinery would be expensive, so the industry has stuck with the format even as design tools have evolved around it.
Common mistakes when creating Gerber files
One frequent error is exporting the wrong layers or forgetting a layer entirely. A designer might export the copper and drill layers but forget the solder mask, which means the manufacturer has to guess where the mask should go. Another mistake is using the wrong units — some software defaults to millimeters, others to inches, and if the designer does not match the manufacturer's expectation, the board comes out the wrong size.
Designers also sometimes export at the wrong resolution or with apertures that are too small for the manufacturer to produce reliably. A trace that is 0.005 inches wide might be theoretically possible but practically impossible on older equipment. Most manufacturers publish design rules that specify minimum trace width, spacing, and hole size, and checking the Gerber files against these rules before sending them prevents costly mistakes.
File naming is another area where errors happen. Manufacturers expect specific naming conventions — like "BoardName_F.Cu.gbr" for the front copper layer — and non-standard names can cause confusion or delays. Many design software packages handle this automatically, but custom exports sometimes require manual renaming.
What happens to Gerber files after the manufacturer receives them
Once a manufacturer receives the Gerber files, they load them into their production software. This software converts the Gerber data into machine code that controls the CNC machines, laser systems, and drilling equipment. The software also performs a final check to make sure the design is within the manufacturer's capabilities.
For a typical circuit board, the manufacturing process involves multiple steps: drilling holes, plating copper, etching away unwanted copper, explore solder mask, printing silkscreen, and testing. The Gerber files guide each step. The drilling machine reads the drill layer and creates holes at the specified coordinates. The etching equipment reads the copper layers and removes copper everywhere except where the traces should be.
Some manufacturers also use Gerber files to generate a visual preview that they send back to the customer for approval before production starts. This preview shows what the finished board will look like and gives the designer a chance to catch any remaining errors.
Gerber files and design software you might encounter
KiCad is free and open-source, widely used by hobbyists and small companies. It exports Gerber files directly and includes built-in design-rule checking. Altium Designer is the industry standard for professional work — expensive but powerful, with excellent Gerber export and integration with manufacturers. Eagle, owned by Autodesk, is popular for mid-range projects and has a free version with limitations.
Smaller tools like EasyEDA and CircuitMaker also export Gerber files and are easier to learn for beginners. Most of these tools include templates and tutorials for exporting Gerber correctly, and many have direct integration with manufacturers — you can upload your design and order boards without manually creating Gerber files yourself.
Frequently Asked Questions
Can I open and view a Gerber file on my computer?
Yes, but you need specialized software. Free viewers like Gerbv and online tools like Gerber Viewer let you see what the board will look like. Your design software can also open Gerber files, though you cannot edit them — they are meant to be read-only once exported.
What if I make a mistake in my Gerber files and the manufacturer already started production?
Contact the manufacturer when ready. If production has just started, they may be able to stop and correct the files. If the boards are already manufactured, you will likely have to pay for a new run. This is why checking Gerber files before sending them is important.
Do I need to create Gerber files myself, or can the manufacturer do it?
Most manufacturers expect you to provide Gerber files, but some offer a conversion service if you send them your native design file instead. This usually costs extra and takes longer, so exporting Gerber yourself is faster and cheaper.
Are Gerber files the same for every manufacturer?
The format is standardized, but manufacturers have different capabilities and design rules. A Gerber file that works for one manufacturer might not work for another if it specifies trace widths or hole sizes outside their range. Always check the manufacturer's design rules before exporting.