What Is the Gerber File Format

The Gerber file format is the standard format used to describe printed circuit board (PCB) manufacturing layers. Gerber files contain the graphical information needed to produce copper layers, solder masks, silkscreen layers, paste layers, board outlines and other PCB fabrication data.

A complete PCB manufacturing dataset normally contains several Gerber files, with each file representing one physical or functional layer of the board. These files are usually combined with Excellon drill files and other manufacturing data before the board is sent for fabrication.

Gerber PCB File Format Description

Gerber was originally developed by Gerber Systems Corporation and is now maintained by Ucamco. The format has evolved over time to support modern PCB manufacturing requirements while remaining widely accepted by PCB manufacturers around the world.

Gerber files are ASCII-based vector files. They describe PCB geometry using coordinates, apertures, draws, flashes, regions and attributes. This makes the format compact, reliable and suitable for transferring accurate manufacturing data between PCB design software, CAM tools and fabrication systems.

Because Gerber is focused on manufacturing output, it is not the same as a PCB design project file. Instead, it is a production format created from the PCB design and used to manufacture, inspect, document and archive the final board data.

Common Gerber File Extensions

Gerber file extensions may vary depending on the PCB design software used, but many follow common naming conventions.
Typical examples include:

The exact extension is not always enough to identify the layer purpose with certainty. Modern Gerber files may include attributes that describe the layer function more clearly.

Gerber File Format Variants

RS-274D - Legacy Gerber

RS-274D is the original legacy Gerber format. It describes PCB layer geometry but does not include aperture definitions inside the file. Because of this, RS-274D files normally require a separate aperture list that defines the shapes used for pads, traces and other objects.

Missing or incorrect aperture files can cause manufacturing problems, so RS-274D is now considered obsolete for most modern PCB production workflows.

RS-274X - Extended Gerber

RS-274X, also known as Extended Gerber, improved the format by embedding aperture definitions directly in the Gerber file. This made Gerber data easier to exchange and reduced the risk of missing or mismatched aperture information.

Extended Gerber also supports more advanced features such as polygon areas, flashes, complex shapes and embedded format information. It became the preferred Gerber format for PCB manufacturing.

Gerber X2

Gerber X2, introduced in 2014, extends RS-274X by adding standardized attributes and metadata. These attributes can describe the file function, layer type, part type, object information and other manufacturing-related details.

This makes Gerber X2 more self-describing and helps reduce ambiguity when PCB data is transferred between designers, manufacturers and assembly partners.

Gerber X3

Gerber X3 is a further extension of the Gerber format. It adds support for component and net information, making it possible to include more assembly-related data together with the PCB manufacturing layers.

By adding information such as component placement, orientation and identification, Gerber X3 helps improve communication between PCB design, fabrication and assembly workflows.
Gerber X3 was first introduced in 2019 by Ucamco.

How Gerber Files Are Used in PCB Manufacturing

Gerber files are exported from PCB design software and sent to the PCB manufacturer as part of the fabrication package. The manufacturer uses these files to create the physical layers of the board, including copper routing, solder mask openings, silkscreen markings and paste stencil data.

Before fabrication, it is important to verify that all required layers are present and correctly aligned. Viewing the Gerber files together with drill data helps detect possible issues such as missing board outlines, incorrect layer polarity, misplaced drill holes or incomplete solder mask data.

Open and Convert Gerber Files with GerbView

GerbView supports commonly used Gerber file variants, including legacy RS-274D, RS-274X Extended Gerber, Gerber X2 and Gerber X3. You can open Gerber files together with Excellon drill data and other PCB manufacturing layers to inspect the complete board before fabrication.

With GerbView you can view Gerber files together with drill data and other PCB manufacturing layers, making it easier to verify copper traces, solder mask alignment, silkscreen placement, board outlines and overall output quality before fabrication.

GerbView can also print, markup, compare and convert Gerber files to formats such as PDF, DXF, SVG and image formats.
If you need to update older Gerber files, see our legacy Gerber to extended Gerber conversion tutorial.

Learn About PCB Manufacturing File Formats

Gerber files are only one part of a complete PCB manufacturing package. Excellon drill files, ODB++ data, pick-and-place files, netlists and assembly drawings may also be included depending on the production workflow.

Learn more about PCB manufacturing file formats

Related Information