SageThumbs covers 162 image formats (224 extensions) through the GFL library, plus 26 more formats when XnView plugins are present. That official figure — from the project’s own site, ReadMe and SourceForge page — makes it one of the broadest Explorer thumbnail extensions ever released for Windows. This guide explains what that number actually contains, how the format families group together, and, just as importantly, which popular formats are not on the list, so you never plan a workflow around a preview that will not appear.
The enumeration behind the figure lives on the author’s official formats page. A careful count of that page produces 215 listed entries rather than exactly 224, a small discrepancy in the project’s own materials that we note rather than tidy away: the headline figure of 162 formats (224 extensions) is the project’s stated number and is the one we use, while the enumerated page is the place to check whether a specific extension appears.
The format families that matter
Most users care about families, not alphabet soup. The everyday bitmap and photo formats are there — JPEG, PNG, GIF, BMP, TIFF and their many variants. Layered and editor documents are a strength: PSD for Photoshop, XCF for GIMP, and PSP formats for PaintShop Pro, which between them cover the project files most people actually hoard. Game and graphics-asset formats include DDS textures and TGA, plus a deep bench of legacy and specialist types from the history of computer graphics. Icons and cursors (ICO, CUR, ANI) are covered, as are Windows metafiles in the enumeration. Camera RAW is well represented: CR2, CRW, NEF, ARW, SR2, RAF, ORF, PEF, DNG, RW2, MRW, X3F and KDC/DCR. And with AFPL GhostScript 8.54 installed, the PostScript family — AI, EPS, PS and PDF — joins the list through interpretation rather than direct decoding.
- Documents and layered files: PSD, XCF, PSP family.
- Camera RAW: CR2, CRW, NEF, ARW, SR2, RAF, ORF, PEF, DNG, RW2, MRW, X3F, KDC, DCR.
- Game and graphics assets: DDS, TGA and many legacy formats.
- Icons and cursors: ICO, CUR, ANI.
- Via GhostScript 8.54: AI, EPS, PS, PDF.
- Via XnView plugins: 26 additional formats on top of the GFL list.
What is not supported — stated plainly
Classic SageThumbs does not support WebP, SVG, HEIC, AVIF, INDD or CR3. None of those extensions appears in the official enumeration, and any page claiming this extension previews them is wrong. The pattern behind the absences is the project’s timeline: the last release was 2.0.0.23 in May 2017, and several of these formats became everyday only afterwards. HEIC arrived with newer phones, CR3 with newer Canon bodies, and WebP and AVIF spread through the web later still.
The workarounds are straightforward, if less elegant. Windows itself, a current image viewer, or a format-specific codec can cover the modern web and phone formats; Canon’s own software or a current codec handles CR3; InDesign documents are best previewed through Adobe’s own tools or an exported PDF. Many people run SageThumbs for its unmatched classic breadth alongside one modern tool for the handful of new formats, which is a perfectly sensible division.
| Format | In classic SageThumbs? | Practical alternative |
|---|---|---|
| WebP | No | Windows support, a current viewer, or convert a browsing copy |
| SVG | No | A browser, an editor, or PowerToys’ SVG thumbnail provider |
| HEIC | No | Windows HEIF support from Microsoft or a current viewer |
| AVIF | No | A current viewer or browser |
| INDD | No | InDesign itself or an exported PDF |
| CR3 | No | Canon software, a current RAW codec, or DNG conversion |
How to check a specific extension
If your workflow depends on one unusual extension, check the author’s official formats page enumeration before assuming. The extension names there are sometimes the format’s internal name rather than the file suffix you know — PaintShop files, for example, appear across several entries — so search the page for a few variants. Then test with a real file: install, restart Explorer, and open the folder. A two-minute test with your own archive settles questions that no list, including this one, can answer for every writer and variant of a format.
Breadth is the point
It is worth pausing on why a 162-format list matters when most people use five formats a week. Archives are not made of the formats you use this week; they are made of every format you have ever used, plus every format clients, cameras, engines and collaborators have ever sent you. A thumbnail tool that covers only the current top five leaves the long tail — the PSP projects, the DDS textures, the XCF drafts, the Kodak RAW files — exactly as opaque as before. Breadth is what makes the whole archive visible at once, in one window, with one install.
Frequently asked questions
How many formats does SageThumbs support?
The official figure is 162 formats (224 extensions) via the GFL library, plus 26 more via XnView plugins. The author’s enumerated formats page lists 215 entries, a small discrepancy in the project’s own materials.
Does SageThumbs support WebP, HEIC or SVG?
No. WebP, SVG, HEIC, AVIF, INDD and CR3 are all absent from the official list. Use Windows’ own support or a current tool for those formats.
Why are newer formats missing?
The last release, 2.0.0.23, dates from May 2017. Formats that became common after that point are simply outside what its decoder was built to cover.
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