PDF compression
Compress a PDF to 100 KB
For the tightest limits: when a form says 100 KB and won’t take a kilobyte more. Runs right in your browser.
Drag & drop your PDF here
or click to browse
What does “under 100 KB” mean?
It’s a very tight limit: about the size of a single typed page with a small logo. You’ll usually see it on a handful of application portals that have to store millions of files, or when someone asks you to send a document over a messaging app that throttles attachments. Because the ceiling is so low, the file can’t carry much photo data and still pass. That’s why the tool has to be more aggressive here than at 300 or 500 KB.
A couple of typed pages will slip under 100 KB without you noticing any difference. A single page that’s mostly a colour photo is a different story: it can, but the image will look softer. We keep the text sharp and ask the images to give way first, because reviewers need to read the words and numbers.
When you actually need 100 KB
Only reach for 100 KB when the site actually asks for it. If the instructions say “up to 200 KB,” the 200 KB tool will give you a clearer result and still pass. Common cases for 100 KB are a scholarship or application form that lists “PDF < 100 KB,” a low-bandwidth upload that times out with anything larger, or a chat where the receiver’s inbox caps attachments.
Think of it this way: you scanned your income certificate on your phone: two pages, 5 MB. The portal immediately says “File too large.” At 500 KB it would look perfect, but the form won’t take it. Here you have to aim for the exact number it checks.
How to get a PDF to 100 KB
You don’t need to prepare the file much: but if it started as a scan, a 30-second fix up front helps a lot.
- Start from the original. Don’t compress a file you’ve already compressed. You’ll just add blur for little extra saving.
- If it’s a scan, rescan lighter if you can. A page scanned in colour at high resolution is three to six times heavier than the same page in grayscale at a modest resolution. Grayscale is usually fine for certificates and forms.
- Drop it here. Shrinklyy will try stronger settings step by step and keep the first one that gets under 100 KB: the clearest version that still fits.
- Zoom to 150% and check. Look at the smallest print, any seal, and a signature. If the lines stay continuous, you’re good. If not, step back to 200 KB.
Why some PDFs won’t reach 100 KB
The tool will try its hardest, but a few kinds of PDFs just don’t have room to shrink that far without becoming hard to read:
It was already made tiny.
If someone exported the PDF with “Smallest file size,” there’s little left to remove. Trying to halve it again trades visible quality for only a small saving.
It’s mostly photos or colour scans.
A colour certificate with a large photo needs lots of pixels to stay crisp. At 100 KB those pages have to give way. Switching that one page to grayscale: or allowing 200 KB: keeps it much clearer than forcing it down.
If the result comes back at 118 KB when you asked for 100 KB, that’s the most the file can shrink while staying readable. Splitting a long PDF into two uploads (if the portal allows it) or asking if 200 KB is acceptable is more honest than submitting a blurry file. More on this in why scanned PDFs are so large.
Will text stay readable?
Usually, yes: especially for typed text. We don’t turn text into an image; we keep the font data for the characters you actually used, so letters stay sharp. What softens first are photos, gradients, and very fine scanned lines. A quick check helps: open the new PDF on your phone before you upload. If you can read the smallest footnote comfortably, the reviewer can too.
If you’re worried, see how to keep text readable while reducing PDF size.
Works where you are, and stays private
It works in Chrome, Edge, Firefox and Safari on desktop and on Android/iOS: the same uploader you see here. And because it runs locally, the PDF never leaves your device. There’s no upload to intercept and no server copy to delete later. That matters most for IDs and other papers you wouldn’t want sitting on a random server.
Frequently asked questions
My colour scan looks soft at 100 KB. What should I do?
Try scanning that page again in grayscale if colour isn’t required, or use the 200 KB target. The extra headroom often makes seals and small print snap back to clear.
Is this the same as Custom → Maximum?
Similar strength, different intent. This tool hunts for the clearest setting that still fits under 100 KB. Custom Maximum always uses the strongest setting, whatever size it happens to land on. Use this page when a portal explicitly checks for 100 KB.