Compress Images for Google Slides — Free, Fast & Private
Google Slides enforces its image rules at three different points, and they trip you up in a specific order:
- Per image on insert — under 50 MB, no more than 25 megapixels, and in PNG, JPEG or GIF.
- Per presentation — a deck converted to Google Slides format is capped at 100 MB.
- In practice, well before either cap: the editor turns sluggish, thumbnails redraw slowly, and collaborators on weaker connections see the deck load a slide at a time.
“Images must be smaller than 25 megapixels”
This is the error that confuses people most, because it has nothing to do with file size. Megapixels are width × height ÷ 1,000,000. A 6000 × 4500 photograph is 27 MP and is refused — even if the JPEG is only 3 MB, comfortably under the 50 MB rule. Compressing the file harder does not help at all; the pixel count is what is being measured.
The fix is to reduce dimensions. Set a max width of 1920px and any modern camera photo drops to about 2 MP — a tenth of the ceiling, and still more pixels than a 16:9 slide can display.
Why Slides gets slow before it gets full
Slides is a web application: every image is decoded in the browser, on every machine that opens the deck. A PowerPoint file with the same images at least renders locally from disk. In Slides, twenty full-resolution photographs mean twenty large decodes, repeated for each collaborator, plus the transfer.
The visible symptoms — slow thumbnail panel, laggy dragging, an image that stays grey for a second after you scroll to it — all improve immediately when the source images are the right size. This is the practical reason to compress, well ahead of the documented limits.
Format choice, briefly
Slides accepts PNG, JPEG and GIF. Use JPEG for photographs — a photograph saved as PNG is routinely five to ten times larger with no visible benefit, and PNG screenshots pasted straight from a phone are a common cause of a bloated deck. Use PNG for screenshots, charts, logos and anything with transparency. WebP and AVIF are not on the accepted list, so convert those to JPEG or PNG before inserting.
MiniPx does all of this in your browser and never uploads anything, which matters when the deck is an internal roadmap or unreleased client work. Drop in a whole folder, set 1920px, and export the batch in one pass.
Related: the PowerPoint version of the same problem · images that go out by email instead