What is the SLDDRT file format?
.slddrt is a SOLIDWORKS Drawing Sheet Format file - a proprietary template that defines the border, title block and table anchors for one sheet size in a SOLIDWORKS drawing.
Unlike a .drwdot Drawing Template (which stores document-level settings such as units and projection angle), a .slddrt file stores only the graphical and structural elements of a single sheet: the sheet size (ISO A0-A4 or ANSI A-E, or custom), border geometry, title-block line work and text annotations, anchor points for bill-of-materials, revision, weldment cut-list and hole tables, and links to model custom properties displayed in the title block.
.slddrt files use the OLE2 Compound File Binary container - the same Microsoft Structured Storage format as .slddrw and .sldprt files. They are opened and edited through SOLIDWORKS' built-in Edit Sheet Format mode and saved via File > Save Sheet Format. They do not contain drawing geometry or model data.
A single .drwdot template can reference different .slddrt files for different sheet sizes within one drawing. Newer SOLIDWORKS releases can generally open .slddrt files from older versions, but older releases may not correctly open files saved by a newer version.
Security & safety
RISK: LOWSLDDRT is a passive CAD template file - no executable code. Opening one in SOLIDWORKS is safe. The only practical concern is that sheet formats from a newer SOLIDWORKS version may not open correctly in an older installation.
Format details
in a nutshellPrograms that open SLDDRT files
Windows2 apps
SolidWorks
Paid Within SOLIDWORKS, open a drawing (.slddrw), right-click the sheet and choose Properties > Sheet Format, then browse to the .slddrt file to apply it. To edit: right-click the drawing > Edit Sheet Format; to save: File > Save Sheet Format. SOLIDWORKS is the only program that opens .slddrt files. 
eDrawings Viewer
Free eDrawings Viewer opens .slddrw drawing files (which contain/reference a sheet format), but it does NOT open .slddrt files directly. Listed for context - view the resulting drawing in eDrawings, not the template file itself. Technical details
deep spec| Container | OLE2 Compound File Binary (Microsoft Structured Storage) |
| Magic bytes | D0 CF 11 E0 A1 B1 1A E1 at offset 0 (OLE2 compound document signature) |
| Encoding | Binary, little-endian (OLE2 convention) |
| Stores | Sheet size, border geometry, title-block line work and notes, table anchor points, custom property links |
| Does not store | Drawing geometry, model data, or document-level settings (those are in .drwdot) |
| Typical size | 50 KB - 5 MB (varies with title block complexity and embedded custom properties) |
| Sheet sizes | ISO A0-A4, ANSI A-E, and custom dimensions |
| Companion file | Referenced by .drwdot Drawing Template; a single .drwdot may reference different .slddrt files per sheet size |
| Platform | Windows only (SOLIDWORKS is a Windows-only application) |
| Version compatibility | Older SOLIDWORKS versions may not open .slddrt files saved by a newer release |
| MIME type | application/octet-stream |
| Edit method | SOLIDWORKS Edit Sheet Format mode; no standalone third-party editor reads this format |
| Released | circa 1995 (SOLIDWORKS 95), as part of the drawing template system |
| Latest version | SOLIDWORKS 2025 (current; format revises with each major SOLIDWORKS version) |
| Specification | www.solidworks.com |
SLDDRT conversions
Community Q&A
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