Free online PHO to GBR converter

PCB fabrication software and board viewers commonly expect Gerber layers with a .gbr extension, while older PCB CAD tools may produce the same photoplot data as .pho. Converting it lets a manufacturer or CAM program load the layer without rejecting the filename or requiring manual file-type selection.

What the PHO format is

In the CAD and PCB context, .pho usually identifies a photoplotter output file containing Gerber artwork for one board layer, such as copper, solder mask, or silkscreen. Legacy PCB design and CAM applications, including Protel- and P-CAD-era workflows, used this extension for plotted circuit-board data.

A PHO file may contain RS-274X extended Gerber commands, or older RS-274-D commands that depend on a separate aperture table. The extension alone does not identify the Gerber generation, coordinate units, polarity, layer purpose, or whether the file includes embedded apertures. Inspect the file in a Gerber viewer before fabrication.

What the GBR format is

.gbr is a common filename extension for Gerber PCB artwork. GBR files are used by PCB layout software, CAM systems, Gerber viewers, and board manufacturers to represent individual fabrication layers.

Modern GBR files generally use RS-274X, which embeds aperture definitions and eliminates many separate aperture-table files. A GBR file still normally represents only one layer; a complete board release also contains other Gerber layers, drill files such as Excellon data, and fabrication notes.

How to actually convert PHO to GBR

Use the 101convert website

1. Open the PHO-to-GBR converter on 101convert.com.
2. Upload the .pho file and choose GBR as the output format.
3. Start the conversion and download the resulting .gbr file.
4. Open the output in a Gerber viewer and confirm the layer alignment, polarity, dimensions, and aperture rendering before sending it for manufacture.

Rename the file when it is already Gerber data

Many PHO files are already Gerber files, so a format conversion is unnecessary. Copy the file, change only its extension, and test it in a viewer:

mv board.pho board.gbr

On Windows Command Prompt, use:

ren board.pho board.gbr

In a desktop CAM application, import the PHO file as Gerber and export it as RS-274X GBR. In Gerbv, KiCad Gerber Viewer, Altium Designer, or another CAM tool, use the import command, set the correct units and coordinate format if the application asks for them, then use File → Export or the equivalent Gerber output command. Do not export the file as an image; PNG, PDF, and raster output cannot replace fabrication Gerber data.

Quality, compatibility, and limitations

Changing .pho to .gbr does not alter coordinates or drawing quality because Gerber is vector plot data. It also does not repair incorrect units, coordinate precision, mirrored layers, negative polarity, obsolete apertures, or malformed commands.

If the PHO file uses RS-274-D, keep its matching aperture file and import both together. Without the aperture definitions, traces and pads may render incorrectly or disappear. If the source contains only one board layer, converting it does not create missing copper, mask, silkscreen, outline, or drill files.

Before fabrication, verify the converted file in a Gerber viewer at 1:1 scale and check the reported board dimensions against the original CAD design. Re-export from the source PCB application instead of converting when the PHO file is incomplete, unreadable, or accompanied by missing aperture data.