Gerber format

The Gerber file format is the de facto standard for printed circuit board (PCB) design data transfer. Known as “the backbone of the electronics fabrication industry”, Gerber format files are output by all PCB design systems and input by all PCB fabrication software, allowing PCB professionals to exchange PCB design data securely and efficiently. 

Gerber files show single images representing copper layers, solder mask, legend, and drill and route data. These are associated with Gerber attributes that transfer meta-information about the files; information that gives the fabricator essential information about the image and its features.

This can include the following:

  • What layer or data is represented within each file: top solder mask, bottom copper layer, etc.
  • Pad function: whether a given flash is an SMD or via pad, or a fiducial, etc.
  • The net number, component reference and pin number of component pads.

Thus a set of well-constructed Gerber files define the PCB image and the function of the objects within it, reliably and productively transferring PCB fabrication data from design to fabrication.

Based on an open ASCII vector format for 2D binary images, the Gerber file format is simple, compact and unequivocal and thanks to its use of printable 7-bit ASCII characters, it is portable and easy to debug. Indeed, all implementations are thoroughly field-tested and debugged. 

The standard file extension is .gbr.

The current Gerber formats are RS-274X or Extended Gerber, either X1 or X2. Standard Gerber or RS-274-D is obsolete and revoked. It was superseded by RS-274X decades ago and should no longer be used. 

The following resources are available to users of the Gerber format, especially software developers:

  • The format specification.
  • An online reference Gerber viewer as a complement to the specification.
  • A tutorial is provided by its chapter “Overview of the Gerber Format”.
  • Two examples of PCB fabrication data sets.
  • A set of test files, containing the constructs that are most often wrongly implemented.

Documents and test files are on the download page.

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