How to compress a PDF to under 100 KB
Open the PDF in a compressor that targets a size, set the limit to 100 KB and download the result. Most of a PDF's weight is its pictures and scans, so those are made lighter while the text stays as it is. Our 294 KB one-page sample scan came out at 96.5 KB; a long PDF full of photos may not get there without becoming hard to read.
Updated 1 October 2026
Compress a PDF to 100 KB, step by step
- Open the compressorGo to Compress a PDF to 100 KB on a phone or a computer and choose your PDF. It opens in the browser tab and is never uploaded.
- Keep the target at 100 KBThe page starts at 100 KB. The file is cleaned first (hidden data, thumbnails, duplicate objects), then the pictures inside are made lighter until the file fits.
- Check the size and the pagesLook at the size shown before you download, and open the result to check the scans are still readable. If 100 KB is out of reach, the page says so and offers the smallest file it made.
- Download and upload to the portalDownload the smaller PDF. It is free, needs no account and carries no watermark.
What makes a PDF bigger than 100 KB
Text is cheap: a page of plain text with its font is a few kilobytes. Pictures are not: one page scanned in colour at 300 dpi can be several megabytes by itself, and a phone photo turned into a PDF is usually larger still. So the question is almost always how many pictures and scans the PDF holds and how large they are stored.
That decides what a compressor can do. It can lower a picture's resolution and use stronger JPEG compression; it should not touch the text, which is already small and must stay selectable.
Will my PDF fit?
It depends on how much of the file is pictures. We ran filedone's compressor on our own two sample scans on 2026-10-01, with the target at 100 KB:
| File | Before | After | Under 100 KB? |
|---|---|---|---|
| Sample scanned PDF, 1 page, 200 dpi | 294 KB | 96.5 KB (98,844 bytes) | Yes |
| Sample multi-page scan, 3 pages, 150 dpi | 369 KB | 88.4 KB (90,478 bytes) | Yes |
- A PDF of several colour photos or high-resolution colour scans has far more picture data to shed, and may not reach 100 KB while staying readable.
- A long text document with several embedded fonts may not shrink much, because text and fonts are kept exactly as they are.
- filedone's compressor will not take pictures below 72 dots per inch to hit a number. If the size is still out of reach, it offers to turn every page into a picture, which is much smaller but leaves no selectable text, and does so only if you say yes.
If you are still over the limit
- Remove pages the portal does not need with Delete PDF pages, then compress again.
- If the portal accepts several files, split the PDF with Split a PDF and send the parts.
- If you are making the PDF from photos, shrink the photos first with Compress an image to 100 KB and join them with JPG to PDF.
- Re-scan at a lower setting — 150 dpi in grayscale is usually enough to read a typed page — rather than squeezing a 600 dpi colour scan.
KB or KiB? How portals count
Some portals count a kilobyte as 1,000 bytes, others as 1,024. filedone's compressor treats "at most 100 KB" as at most 100,000 bytes, counted on the file itself with its metadata, so the file passes under either reading.
Questions
Is it safe to compress a PDF online?
With filedone's compressor the PDF never leaves your device: it is opened and compressed by your browser, and nothing is uploaded. Other online compressors may upload your file; check before you use one for a private document.
Can I compress a PDF to 100 KB on my phone?
Yes. Open Compress a PDF to 100 KB in the phone's browser, choose the PDF and download the smaller file. There is no app to install.
Will the text still be selectable?
Yes, unless you agree to the last-resort option of turning pages into pictures. The text is never touched in the normal path; only the pictures and scans inside are made lighter.
My portal wants 200 KB or 500 KB instead.
Use Compress a PDF to 200 KB or to 500 KB, or pick any size on Compress a PDF.
Is there a test file I can try it on?
Yes: the sample scanned PDF is a one-page 200 dpi scan of about 300 KB, and the three-page scan is larger. Both are free and fictional.
Tools for this
- Compress a PDF to 100 KBBring a PDF under 100 KB for an exam, job or government portal, without uploading it. Text stays selectable; only the pictures and scans inside are made lighter.
- Compress a PDF to a size in KBReduce a PDF's size for free — as small as it goes, or under 100 KB, 200 KB, 500 KB or 1 MB for a portal. Nothing is uploaded; text stays selectable.
- Compress a PDF to 200 KBBring a PDF under 200 KB for an exam, job or government portal, without uploading it. Text stays selectable; only the pictures and scans inside are made lighter.
- Delete pages from a PDFTap the pages you don't want and download the PDF without them. They are removed from the file itself, not hidden. It happens on your own device: nothing is uploaded.
- Compress an image to 100 KBBring a JPG, PNG or WebP under 100 KB for an exam form or a portal, without uploading it. The picture is re-encoded on your own device.
Free sample files to try it on
- Sample scanned PDF for OCR testingOne page, image only, 200 dpi, skewed — the basic OCR test.
- Sample multi-page scanned PDFThree scanned pages, each skewed differently, with two tables.
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