What is the STO file format?
.sto files are associated with PRO100, a furniture and interior design software particularly popular in Poland and Central/Eastern Europe for professional kitchen cabinet and room planning.
What kind of data do STO files contain?
Files with the .sto extension are used by PRO100 to store complete interior design projects. An .sto file contains 3D room dimensions, furniture objects with their positions and orientations, applied materials and textures, pricing and cost information, and project metadata. .sto files are also used for 3D project visualization within the PRO100 interface. Recent versions of PRO100 include manufacturer-specific furniture libraries from popular producers for more accurate and complete designs.
What features does PRO100 offer?
PRO100 is also a capable tool for designing furniture and complete room layouts. It offers many advanced tools for creating custom furniture items or whole sets. It can render 3D visualizations with adjustable lighting and perspective. The program can also generate cutting lists and additional documentation for production. PRO100 is also compatible with board cutting machinery to streamline the furniture manufacturing process.
.sto is a proprietary binary format readable only by PRO100; it cannot be opened by other 3D design applications. File compatibility may vary between PRO100 versions - older .sto files may require migration before opening in a significantly newer release.
Security & safety
RISK: LOWSTO files are 3D project data with no executable content and are safe to handle. The main risk is receiving a STO from an unknown source and finding missing furniture library items, or version mismatch errors if the file was saved in a newer PRO100 version. No malware vector is known for this format.
Format details
in a nutshellFULL NAMEPRO100 Interior Design Projectaka PRO 100 project file, PRO100 3D interior design file
DEVELOPERECRU s.c. (also distributed as PRO100 USA / kam.co.uk)since Late 1990s (PRO100 first Polish/Eastern European release)
CATEGORY3D Image Files
MIME TYPEapplication/octet-stream
TYPEProprietary 3D interior design / furniture-layout project file
This extension is also used by…
- Abaqus FEA Data File - The .sto extension is also used by Abaqus finite-element analysis software for state/output data files; a completely different binary engineering format.
- Sage Accounting Store File (legacy) - Some older Sage accounting products used .sto for store/data files; unrelated to 3D design.
Programs that open STO files
Windows1 app
PRO100
Paid Open PRO100, use File → Open and select the .sto file. Ensure you have the same or a compatible version and the furniture libraries referenced in the project. Technical details
deep spec| Container | Proprietary PRO100 binary project format (undocumented) |
| Platform | Windows only |
| Encoding | Binary; little-endian |
| Stored geometry | 3D room dimensions, furniture objects with position, orientation, and dimensions |
| Stored materials | Applied textures, material properties, and color assignments per object |
| Additional data | Bill of materials (cutting list), pricing information, and project metadata |
| 3D visualization | Scene stored with adjustable lighting settings and camera perspective |
| Compression | Unknown (proprietary; file sizes suggest internal compaction) |
| Version compatibility | Format tied to the PRO100 version that saved the file; older files may not open in significantly newer versions |
| Interoperability | Cannot be opened by other 3D applications; PRO100-exclusive format |
| Typical size | 500 KB - 50 MB depending on furniture count, textures, and materials |
| Primary market | Poland and Central/Eastern Europe (kitchen and furniture design industry) |
| Released | Late 1990s (PRO100 first Polish/Eastern European release) |
| Latest version | PRO100 version 5.x (current as of last known update) |
STO conversions
Possible
.STO .PDFGUIDE
Yes, you can convert a STO file to PDF by printing the project from PRO100, the only program that opens this…
How to convert
.STO .JPGGUIDE
Yes, you can save a STO project as JPG by exporting the 3D view from inside PRO100, the program that created…
How to convert
.STO .3DSGUIDE
Yes, you can export a PRO100 .sto project to 3DS, but only from inside PRO100 itself using File then Export.
How to convert
.STO .DXFGUIDE
Yes, you can convert STO to DXF, but only from inside PRO100 itself, and the cleanest result is a 2D floor…
How to convert
Community Q&A
asked by users
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Frequently asked questions
How do I open a STO file?
You need PRO100 software. There is no free viewer or alternative program that can open PRO100 .sto project files.
What is a STO file?
It is most commonly a PRO100 3D interior design project - a proprietary format storing room layout, furniture placement, materials and pricing. The .sto extension is also used by Abaqus FEA and legacy Sage accounting software.
Can I convert a STO file to PDF or image?
Yes, from within PRO100: use the print or render function to export a PDF quotation or a JPEG of the 3D visualization.
Can I convert a STO file to a standard 3D format like OBJ or 3DS?
Only partially. PRO100 has limited 3DS/DXF export but proprietary furniture models may not transfer accurately to other 3D tools.
I have a STO file but no PRO100 - can I still see the design?
Not without PRO100. There is no free STO viewer. Your best option is to ask the designer to export a PDF or rendered image from PRO100.
References
1PRO100 USA - official sitewww.pro100usa.com
2PRO100 user manual (PDF)www.pro100usa.com
