Free online PHO to PDF converter

What the PHO format is

In the CAD category, PHO is a Gerber photoplotter file used for printed circuit board fabrication. It describes one board layer as 2D graphical data, including copper traces, pads, solder mask, silkscreen, or board outlines, depending on the layer exported.

PCB tools such as KiCad, Autodesk EAGLE, and Altium Designer can create Gerber output using the .pho extension, although many current tools use .gbr instead. A PHO file normally represents only one layer; a complete PCB manufacturing set also contains other Gerber layers, drill files, aperture information, and fabrication notes.

What the PDF format is

PDF is a page-description format designed to preserve graphics, text, page dimensions, and print layout across operating systems. It is suitable for sending a board layer to a customer, adding it to documentation, printing a review copy, or storing a visual manufacturing record.

PDF is not a replacement for editable PCB or Gerber data. It generally preserves the rendered appearance but does not retain the PHO file's manufacturing semantics, aperture definitions, layer metadata, or CAM-tool workflow.

How to convert PHO to PDF

Using the online converter

1. Open the PHO-to-PDF converter on 101convert.com.
2. Select a file with the .pho extension and upload it.
3. Choose PDF as the output format and start the conversion.
4. Download the resulting PDF and check its page size, orientation, scale, and layer visibility before using it for manufacturing documentation.

This method requires no installed CAD or CAM software and is appropriate when the goal is a viewable copy rather than further PCB editing.

Using KiCad Gerber Viewer

1. Install KiCad and open Gerber Viewer.
2. Use File → Open Gerber Plot or the equivalent file-open command, then select the PHO file.
3. Verify the rendered layer, polarity, units, and alignment. If the PHO belongs to a multilayer board, load the related Gerber layers as well.
4. Choose File → Print, select a system PDF printer such as Microsoft Print to PDF or Save to PDF, and save the output.
5. Set the paper size and orientation, disable automatic scaling when a 1:1 representation is required, and confirm the preview before printing.

Quality and compatibility limitations

A PDF made from one PHO file shows only that layer unless the converter or viewer explicitly combines multiple layers. Load and verify the complete Gerber set when the intended PDF is a board overview.

For dimensional review, use a known scale or include a dimension reference; printer settings such as Fit to page can change the physical scale. Thin tracks, negative layers, filled zones, and mirrored artwork can also appear incorrectly if the viewer interprets polarity or rendering settings differently from the original CAM application.

Keep the original PHO files for fabrication. PDF conversion is primarily a visual export and should not be used as the source for generating replacement manufacturing data.