Compress PDF to Under 1MB — Free Online

PDFs become large mainly due to embedded images — especially scanned pages (which are essentially photos) and exported presentation slides with high-resolution graphics. A 10-page PDF with scanned pages at 300 DPI can easily be 20–50MB. Compressing the embedded images to screen resolution (72–120 DPI) typically reduces file size by 70–90%.

Yes — PDF compression primarily targets embedded images, not text. Text in PDFs is stored as vector data (mathematical descriptions of shapes), which compresses efficiently without quality loss. Even at Maximum compression, all text remains sharp and fully readable.

PDFs that contain mostly text with minimal images are already at near-minimum size — compressing them further has little effect. If your PDF is 500KB and text-heavy, that may be close to the minimum possible size. Scanned documents and image-heavy PDFs compress far more dramatically.

Screen (72 DPI) — smallest possible file, suitable for reading on screen only. Low (96 DPI) — very small file, acceptable for digital reading. High (120 DPI) — good quality for screen and basic printing. Maximum balances quality and size for most purposes. Print (150 DPI) — larger file, acceptable for home printing.

200KB is achievable for most 1–3 page PDFs containing only text and simple graphics. Use Maximum compression. If the result is still over 200KB, the PDF likely contains high-resolution embedded photos — try removing or reducing image count before compressing. A single full-page scanned photo at Maximum compression is typically 50–150KB, so a 2-page scan should reach under 200KB.

Yes — PDF compression only targets embedded image data. Text, interactive form fields (checkboxes, text inputs), bookmarks, links, and metadata are not affected. However, compressing a PDF that has been digitally signed (with a cryptographic certificate) may invalidate the signature, as the file's hash changes. Do not compress a cryptographically-signed PDF after signing.

It depends on content. If the PDF is mostly text with minimal images, 500KB is likely close to the minimum possible size — compression will have little effect. If it contains embedded photos or scanned pages, try High or Maximum compression. Check the result size to see if it meaningfully reduces.

DPI (dots per inch) measures the resolution of images embedded inside the PDF. At 300 DPI an image is high resolution — ideal for print but unnecessarily large for screen viewing. Compressing to 72–96 DPI reduces each embedded image to screen resolution: the images look identical on screen, but the file stores far less data. This is why text is unaffected — text in PDFs is not stored as an image.

The tool runs entirely in your browser and uses your device's memory. Most PDFs up to 200–300MB work fine on a modern device. Very large PDFs (300MB+) may be slow to process or could exceed browser memory limits on older devices. For very large PDFs, consider splitting them into smaller sections first using the Split PDF tool.