Free online converter for converting files to PLT.
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| Data type | Vector image / Plotter instructions |
| MIME type | application/vnd.hp-HPGL |
| Developer | Hewlett-Packard (HP) |
| Primary use cases | Plotter output for CAD/technical drawings, cutting/plotting workflows, legacy plotting interchange |
PLT is most commonly an HP-GL plotter file: a text-based vector command stream used by CAD/plotter workflows to draw lines, arcs, and text via pen-plotter instructions.
| Data type | Vector image / Plotter instructions |
| MIME type | application/vnd.hp-HPGL |
| Structure type | Text instructions + optional device/state settings (pens, scaling, coordinate system); no embedded bitmap container by default |
| Container format | Plain-text (typically ASCII) command stream in HP-GL/HP-GL/2: sequential drawing instructions (pen select, pen up/down, absolute/relative moves, arcs, labels). Coordinates are in device plotter units; many toolchains assume 1016 plotter units per inch. |
| Metadata | Very limited: primarily drawing instructions and device state. No standardized Exif/XMP container in HP-GL streams; any extra annotations are tool-specific. |
| Standard / Specification | HP-GL / HP-GL/2 reference documentation |
| Typical file size | Usually small to moderate (KB–MB) for line drawings; can grow large for very detailed paths or dense hatch patterns |
| Year introduced | 1977 |
The PLT file format offers several advantages that make it suitable for common use cases.
The PLT file format has certain limitations that may affect its use in specific scenarios.
PLT vector files are supported by a wide range of design and graphics applications.
Treat PLT/HPGL as untrusted input: malicious or extreme coordinate/command sequences can cause excessive CPU/memory use in parsers/renderers. Use robust libraries, apply limits, and avoid direct execution on real devices without validation.
Vendor specification; publicly documented reference guides and widely implemented