Job portals, government e-filing sites, university admissions and visa applications often cap uploads at 100 KB, 200 KB or 500 KB, far below what an email allows. A scanned certificate or a two-page form from a phone scanner is usually 1 to 5 MB, so the upload fails.
Hitting a strict limit is mostly about images, because text takes almost no space. This guide shows what is realistic for each kind of document, the quickest fix to try first, and a fallback that works when ordinary compression is not enough. If you only need a file small enough to email, the email size guide is the better fit.
What fits in 100 KB
A rule of thumb before you start, so you know which route to take:
- Text-only PDFs exported from Word or Google Docs: often under 100 KB already, even at several pages.
- One scanned page in grayscale at 150 DPI: usually 60 to 150 KB after compression.
- One scanned page in color, or a phone photo of a document: usually 150 to 400 KB unless the resolution is reduced.
- Several scanned pages: rarely under 100 KB in total. Plan to upload only the pages that are asked for.
Step by step: compress first
Open Compress PDF
Drop your file into Compress PDF. No account is needed.
Choose the Screen setting
Screen lowers images to 72 DPI. It is the most aggressive option and stays readable on screen for most documents. Ebook (150 DPI) keeps more detail if Screen makes small print hard to read.
Check the size
The result shows the new size before you download. If it is under the limit, open it and zoom into the smallest text to make sure it is still legible. If the file could not be made smaller, the tool tells you so and you can keep your original.
Still over the limit? Upload fewer pages
Most strict limits are meant for a single page, such as a certificate, an ID card or a signed declaration. If your PDF has extra pages, open Split PDF, select only the page that was asked for, and compress that page on its own. One page is far easier to bring under 100 KB than a whole scan, and the page extraction guide shows exactly how to pull it out.
The fallback: rebuild the page from a smaller image
For a scanned or photographed page that will not shrink enough, rebuilding it gives you direct control over the size. This route runs entirely in your browser:
Turn the page into an image
PDF to JPG converts each page of the PDF into a JPG image.
Compress the image
In Compress Image, lower the quality until the image is comfortably under the limit, for example 80 KB for a 100 KB cap. Grayscale documents compress best. The image size guide shows how cropping and resizing first make this easier.
Turn it back into a PDF
Use JPG to PDF to wrap the image in a PDF. The PDF adds only a few KB on top of the image itself.
Avoid the problem at the source
If you are scanning the document yourself, a few settings make a small file far easier to reach:
- Scan in grayscale rather than color, unless color matters. Stamps and blue ink usually stay clear in grayscale.
- Scan at 150 DPI. 300 DPI holds four times as much data and is only needed for printing.
- Use your scanner app's document mode, which turns the background clean white and compresses far better than a plain photo.
- Crop away table edges, fingers and shadows before saving.
Frequently asked questions
Can every PDF be compressed to 100 KB?
No. A multi-page color scan holds too much image data to fit without becoming unreadable. Upload only the pages that are required, or rebuild them as compressed grayscale images.
Will the text still be readable?
Real text, the kind you can select, stays perfectly sharp at every setting. Scanned text is part of an image, so check the smallest print after compressing and switch from Screen to Ebook if it blurs.
Is my document uploaded?
Compress PDF sends the file to our server over HTTPS for the Ghostscript step and deletes it as soon as the result is returned. Split PDF, PDF to JPG, Compress Image and JPG to PDF all run in your browser.
What if the portal wants a JPG under 100 KB instead?
Follow the fallback route and stop after compressing the image, then upload the JPG itself.
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