Compress a PDF to 100 KB, 200 KB or under 1 MB

What decides whether 100 KB is reachable

Text and vector drawings are tiny; pictures are large. A one-page letter typed in a word processor is often already under 100 KB, and compression has little to remove. A phone-scanned page is a picture of the whole sheet, and a 300 dpi A4 scan is 2480 × 3508 pixels. At the target's lowest setting, 72 dpi, the same page becomes about 595 × 842 pixels stored as JPEG, which is where one- or two-page scans can usually fit under 100 KB while staying readable.

Page count is the other half. Every page carries its own picture, so a limit that a two-page scan meets may be impossible for ten pages at any readable quality. As a rule of thumb, divide the limit by the number of scanned pages to see how much each page gets; a few kilobytes per page is not enough for legible text.

Compress to a target step by step

1. Open Compress PDF with the button below. Target size is selected and set to 100 KB; type 200, 500 or 1000 for other limits, or pick a preset.
2. Add the PDF. Each row shows the page count and a preview of the first page.
3. Keep the method on Keep text for documents with real text. Choose Flatten pages for scans or if the first run misses the target.
4. Click Compress. The tool tries up to seven settings, from 300 dpi down to 72 dpi, each time starting from the original file, and keeps the lightest one that fits.
5. Read the result row: it says Under 100 KB with the resolution used, or Target missed with the smallest size it could produce.

Keep text or Flatten pages

Keep text shrinks only the pictures inside the PDF and copies text, fonts, links and form fields unchanged. It is the right method for anything you or the recipient might search, copy from or fill in. Its limit is that fonts and page structure still take space, and some scanner encodings are left as they are.

Flatten pages turns every page into a single JPEG picture at the chosen resolution. It works on any PDF and gives the lowest floor, which makes it the method most likely to reach 100 KB for a scan. The cost is that text can no longer be selected or searched, and links and form fields disappear. For a scanned certificate that was never searchable, that is a fair trade; for a filled-in form it is not.

When the target is still missed

• Split the document if the form allows several files: Split PDF can save each page separately, and each page then gets the whole limit.
• Remove pages the form does not need, such as blank backs of scanned sheets or cover pages.
• Rescan in black and white or greyscale if the source is a paper document; colour scans of black text waste bytes on paper tone.
• Check whether the limit really is 100 KB. Some forms state KB but mean MB, or accept larger files by email instead.

What the tool will not do is hand back an unreadable document just to meet a number. Below 72 dpi small print breaks up, so the search stops there and tells you.

Check the result before you submit

1. Click the result thumbnail to compare pages with the original, and zoom in on the smallest text.
2. Check the page count and, for Keep text, that form fields and links still work.
3. Confirm the byte size in your file manager: 100 KB means at most 100,000 bytes here.
4. Keep the original PDF. The compressed copy is for the upload.

Encrypted and digitally signed PDFs are rejected with an explanation because rewriting them would break the protection or signature. Remove the password first with Unlock PDF if you are allowed to, and keep the signed original.