Compress PPTX
Shrink oversized presentations by recompressing images and stripping thumbnail data.
100% in your browser — files never leave your device
Why presentations get large — and how to shrink them
PowerPoint files accumulate size from three main sources: high-resolution photos pasted directly from a camera or stock library, a hidden preview thumbnail PowerPoint saves inside the file for Windows Explorer previews, and inefficient ZIP compression on the internal XML and asset files.
This tool addresses all three. JPEG images are re-encoded at your chosen quality level — at 70%, a 4 MB photo typically shrinks to under 500 KB with no perceptible difference on a projected slide. The thumbnail file is deleted. And the entire archive is repackaged at maximum DEFLATE compression. The resulting file opens normally in PowerPoint, Keynote, and Google Slides.
Because everything runs in your browser, your deck — including any confidential charts, customer logos, or unreleased product screenshots — never leaves your device during processing.
Frequently asked questions
Are my files uploaded to compress the presentation?
No. Compression runs entirely in your browser. The PPTX is processed in memory and offered as a download — nothing leaves your device.
What does the compressor actually do to reduce file size?
Three things: it re-encodes JPEG images at your chosen quality level (defaulting to 70%), removes the embedded preview thumbnail stored at docProps/thumbnail.jpeg, and re-zips the archive at maximum DEFLATE compression. PNG images are skipped because canvas re-encoding ignores the quality parameter and typically produces larger files than the originals.
Why is my file barely smaller after compression?
If the presentation contains mostly text, shapes, or charts with no embedded images, there is little for the compressor to work with. The thumbnail removal and re-compression of the ZIP container may still produce a small reduction, but image-heavy decks see the most benefit.
Will compression affect how the presentation looks?
At 70% quality the difference is rarely visible on a projected slide. At lower quality settings, heavy photographic content may show JPEG artifacts when zoomed in closely. The presentation structure, text, fonts, and vector graphics are never altered.
What is the quality slider range?
The slider goes from 30% (smallest file, visible quality loss) to 95% (near lossless, minimal size reduction). The default of 70% is a reasonable balance for most presentation use cases.