Compress PowerPoint Files Online: Free

PowerPoint decks gain weight quickly. Drop in a few phone photos, paste some full-resolution screenshots, add a stock image per slide, and a 20-slide presentation can easily pass 50 MB: too large for most email gateways, slow to upload to Teams or SharePoint, and sluggish to open on older laptops. Our PowerPoint compressor reduces PPTX file size by up to 90% while leaving every slide exactly as you designed it.

The tool works with the file's real structure rather than blindly re-saving it. A PPTX file is a ZIP archive following the Office Open XML standard: slides are small XML files, and nearly all of the weight sits in the ppt/media/ folder as embedded JPEG and PNG images, frequently stored at full camera resolution even when they occupy a quarter of a slide. The compressor re-encodes those images with quality-tuned settings, downscales pictures that are dramatically larger than any projector will ever display, strips redundant data, and repacks the whole archive with maximum deflate compression. Slide text, animations, transitions, layouts, embedded fonts, and speaker notes are untouched.

Pick the level that fits. Low is effectively lossless: images are left alone and the archive is simply repacked with stronger deflate settings, a safe choice when pixel-perfect imagery matters. Medium, the recommended default, re-encodes images at high visual quality and trims oversized ones; the difference is invisible on a projector. High applies more aggressive quality tuning and downscaling for the smallest possible file: ideal for email or archiving.

Honest results, no surprises. Savings depend on what is inside the deck. Photo-heavy presentations routinely shrink 50–90%, while a text-and-shapes deck has little raster data to optimize. If compression cannot produce a smaller file, you simply get your original back: never a "compressed" copy that is somehow bigger. Legacy .ppt presentations are first upgraded to the modern .pptx format, then compressed.

Private by design. Files transfer over HTTPS, are processed in an isolated server-side directory, and automatically delete (after about two hours without an account; account files follow your plan): the download card also offers a Delete File Now button if you want them wiped immediately. Free accounts can compress presentations up to 500 MB. Once your deck is lighter, convert it to a shareable PDF with PPTX to PDF, shrink companion files with Compress Word, or optimize handouts with Compress PDF.