What is the PSDT file format?
A .psdt file is an Adobe Photoshop document template - structurally identical to a standard .psd file but saved with the .psdt extension so that Photoshop treats it as a protected template. When opened, Photoshop creates a new Untitled document based on the template rather than opening the file itself, preventing accidental overwriting of the original design - the same convention Microsoft Word uses with .dotx template files.
The binary format is identical to PSD: a four-byte 8BPS signature, a version field (1 for standard PSD, 2 for the large-document .psb variant), followed by blocks for color mode, image resources, the full layer tree with masks and effects, linked smart objects, and the flattened composite image. Photoshop applies PackBits RLE or ZIP compression per layer channel.
.psdt files populate the File > New dialog's Templates panel. Custom templates can be added by placing .psdt files in the user's Photoshop Templates folder. Any existing .psd can be turned into a template by saving it via File > Save As and selecting the Photoshop Template format.
Color depth support matches PSD fully: 8, 16, or 32 bits per channel in RGB, CMYK, Grayscale, Lab, or multichannel modes. Maximum canvas size is 30,000 × 30,000 pixels; using the .psb large-document format extends this to 300,000 × 300,000 pixels. Photopea and GIMP can open .psdt files by treating them as standard PSD documents.
Security & safety
RISK: LOWPSDT is a design/image template format - not executable. Same risk profile as PSD: avoid unofficial 'PSDT viewer' download sites (often adware/PUPs). Prefer opening in Photoshop or Photopea directly. A PSDT won't execute code.
Format details
in a nutshellPrograms that open PSDT files
Windows4 apps
Adobe Photoshop
Paid Double-click the PSDT; Photoshop opens it as 'Untitled' ready to customize and save as PSD. 
Affinity Photo
Paid Open PSDT as a PSD document with layer support; one-time purchase alternative to Photoshop. 
macOS3 apps
Photopea
Freemium Drag PSDT into Photopea browser editor; full layer support without installing anything. Technical details
deep spec| File signature | 8BPS (hex 38 42 50 53) - identical to .psd; Photoshop uses the file extension, not the header, to apply template behaviour |
| Byte order | Big-endian |
| Version field | 0x0001 = standard PSD (max 30,000 × 30,000 px, 2 GB file limit); 0x0002 = PSB large-document |
| Layer support | Full PSD layer tree: pixel layers, groups, masks, adjustment layers, smart objects, fill layers, and layer effects |
| Color modes | Bitmap, Grayscale, Duotone, Indexed, RGB, CMYK, Lab, Multichannel |
| Color depth | 1, 8, 16, or 32 bits per channel |
| Channel compression | PackBits RLE or ZIP (with or without prediction) applied per layer channel; Photoshop selects automatically |
| Canvas size limit | 30,000 × 30,000 px (PSD); 300,000 × 300,000 px (PSB large-document variant) |
| Template behaviour | Opening creates a new Untitled document; original .psdt file is never modified - mirrors .dotx behaviour in Microsoft Word |
| Template location | User Photoshop Templates folder; files appear automatically in the File > New dialog Templates panel |
| Linked asset support | Supports linked and embedded Smart Objects with full round-trip editing back to source files |
| MIME type | image/vnd.adobe.photoshop |
| Released | 2013 (introduced with Photoshop CC / the New Document dialog redesign) |
| Latest version | Same underlying PSD spec; APX version 2 (large doc) |
| Specification | www.adobe.com |
PSDT conversions
Community Q&A
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