How to compress a PDF to 100 KB

A scanned document or an image-heavy PDF can easily be 5–20 MB — too big to email, and over the limit on most upload forms. The fix is to compress it. Here is how to bring a PDF down to around 100 KB (or whatever size you need) while keeping the text clear.

The quick way

1. Open the free Compress PDF tool.
2. Choose your PDF.
3. Type the size you need under "Compress to" (for example 100 KB). The PDF comes out just under that size.
4. Download the smaller file.

Why is my PDF so large?

Most of the size in a big PDF comes from images — scanned pages, photos or screenshots — not the text. A PDF that is only text is usually already small. So compression mainly works by storing those images more efficiently and at a sensible resolution. If your PDF is a scan, expect the biggest savings.

Getting to a specific size

If a form says "under 100 KB", aim a little below it so there is room to spare. Very small targets on a scanned, multi-page document can soften the text — if that happens, try splitting the file (upload fewer pages) or accept a slightly larger size. For a document that is mostly text, 100 KB is usually easy without any visible loss.

Tips

• Black-and-white documents compress better in grayscale — try Grayscale PDF first.
• Too many pages for one small file? Split the PDF and send the part you need.
• Only have photos, not a PDF yet? Make a lean PDF with Image to PDF.