Compress PDF to 100 KB
Get your PDF under 100 KB for an exam, job or government form, with every word still readable.
or drop PDFs here
Batch supported · paste with Ctrl+V · up to 100 MB per file
Pick the size your portal or email allows. You get the best quality that fits, and a clear message if it cannot fit while staying readable.
Scanned certificate, mark sheet or ID? Choose Black & white scans in the options. That is how scanned pages get under 100 KB and stay sharp.
Your PDF is sent over an encrypted connection and compressed on our server. The working copy is deleted before your download begins, and nothing is kept.
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What fits in 100 KB
To see what it really takes to compress PDF to 100 KB, we compressed six kinds of document with that target. This is what came out, measured on real files, not estimated.
| Document | Original | Colour | Grey | Black & white |
|---|---|---|---|---|
| 1-page PDF with one phone photo | 987 KB | 71 KB · fits | 80 KB · fits | 80 KB · fits |
| 1-page colour scan | 2,571 KB | 208 KB · over | 204 KB · over | 64 KB · fits |
| 2-page colour scan | 2,837 KB | 237 KB · over | 227 KB · over | 65 KB · fits |
| 3-page colour scan | 4,259 KB | 354 KB · over | 340 KB · over | 97 KB · fits |
| 12-page report with photos | 16,999 KB | 147 KB · over | 118 KB · over | 118 KB · over |
| 20-page text document | 22 KB | 22 KB · fits | 22 KB · fits | 22 KB · fits |
Two things stand out. Scanned pages only fit in black and white: in colour or grey a single scanned page stopped at around 204 to 208 KB, the smallest size at which its small print stayed readable, while in black and white the same page came to 64 KB and a three-page scan to 97 KB.
And some documents are simply too big for 100 KB. The twelve-page report full of photos stopped at 118 KB, because going further would have blurred its pictures past the point of use. If that happens, the tool tells you plainly instead of handing back an unreadable file.
How to get a PDF under 100 KB
- 1
Add your PDF
To compress PDF to 100 KB, there is nothing to set up: the target is already Under 100 KB. Add one file or several at once.
- 2
Choose Black & white for scans
If the PDF is a scan or a photo of paper, pick Black & white scans under Colour. Pages with real text keep it.
- 3
Compress and check the badge
A green Under 100 KB badge means the file is ready. An amber Over 100 KB badge means it needs one more step.
- 4
Trim pages the form does not need
Forms usually want one certificate, not a whole bundle. Remove extra pages with Extract Pages, then compress again.
- 5
Compare before you upload
Press Compare and zoom in on names, numbers and seals, the parts an examiner actually reads.
Why scans are the hard part at 100 KB
A scan is not text, it is a picture of paper. Kept in colour or grey at 100 dpi, the lowest resolution at which small print stays reliably readable, one A4 page takes roughly 200 KB on its own. That is twice the limit before a second page is even added.
Black and white changes the arithmetic. Each pixel becomes a single bit, ink or paper, and the page compresses the way a fax does. At 150 dpi, fax quality, a full A4 page of text came to about 60 KB in our tests, and the text read more cleanly than the colour original because the grey paper tint and scanner noise disappear.
A generic PDF size reducer simply keeps squeezing until the number looks right. We stop at 150 dpi for black and white and 100 dpi for colour on purpose. Below that, figures start to blur into one another: in testing, 18,500 in a scanned agreement became hard to tell from 16,500 at 72 dpi. A form rejected because a mark or a roll number cannot be read is worse than one that needs a second try.
What 100 KB really means
Websites count kilobytes in two ways. Some mean 100 KB as 100,000 bytes, others as 102,400. A file of 101,000 bytes passes one and fails the other.
This tool aims under 100,000 bytes, so a file marked Under 100 KB passes whichever way the form counts. Whether a form asks for a file less than 100 KB or below 100 KB, that is the figure it checks. If it states its limit in bytes, that number is the one to trust.
Where 100 KB limits come up
Exam applications
Registration forms often ask for certificates, caste or category proofs and identity documents as separate small PDFs.
Job portals
Recruitment sites commonly cap each supporting document, so a résumé and each certificate have to fit on their own.
Scholarships and admissions
Portals that collect mark sheets, income certificates and bonafide letters tend to set tight limits per file.
Government services
Online applications for licences, certificates and registrations frequently ask for proofs under a fixed size.
Limits differ from form to form and change over time, so always check the exact figure printed next to the upload box.
If it still will not fit
Go smaller anyway
When a file stops above the limit, the result offers Go smaller anyway. It lets pictures drop below the readable floor. Use it only after checking the result with Compare, because small print may blur.
Upload fewer pages
Most forms want a single page per document. Keep only the page asked for with Extract Pages.
Split one PDF into several
If the form accepts more than one upload, break a long document into parts with Split PDF and compress each part.
Scan again, simpler
A fresh scan at 200 dpi in greyscale starts much smaller than a 600 dpi colour scan, and compresses further.
Crop the margins
Wide blank borders are still pixels. Trim them with Crop PDF before compressing.
Before you upload
No password on the file
Many application portals reject password-protected PDFs outright. This tool keeps a PDF's password on the smaller copy, so if yours has one, remove it with Unlock PDF first, then compress.
The right pages, the right way up
Open the result and check that only the requested pages are there and none are sideways. A rotated certificate is a common reason for a document to be sent back.
Seals, signatures and numbers readable
Use Compare to zoom into the parts that get checked: roll numbers, dates, stamps and signatures. If any of them blur, go back to Black & white rather than Go smaller anyway.
A plain file name
Some portals choke on long names or special characters. A short name such as class10-marksheet.pdf avoids a failed upload.
The size shown by the form
After uploading, most forms display the size they received. If it says anything over 100 KB, the form is counting differently, and a file that passed here will still be under 100,000 bytes.
Frequently asked questions
How do I compress a PDF to 100 KB?
Add your PDF on this page, where the target is already set to Under 100 KB, and press Compress. For scanned documents choose Black & white scans first. A green Under 100 KB badge means the file is ready to upload.
Why will my scanned PDF not go under 100 KB in colour?
A scanned page is a picture, and in colour or grey it needs about 200 KB to keep small print readable. In black and white the same page took about 64 KB in our tests, so choose Black & white scans.
Will my certificate still be readable?
Yes. The tool never goes below 150 dpi for black and white or 100 dpi for colour unless you choose Go smaller anyway, and you can check every file with Compare before downloading.
Is 100 KB the same as 100,000 bytes?
Not always. Some sites count 100 KB as 102,400 bytes. This tool aims under 100,000 bytes, so the result passes either way.
Can I compress several PDFs to 100 KB at once?
Yes. Add them all, compress them together, and download each one or all of them as a single ZIP.
What if my PDF is already under 100 KB?
Then nothing needs to change, and you get your original back untouched.
What does Go smaller anyway do?
It lets pictures go below the readable floor to reach the limit. Only use it after checking the result with Compare, because small print may blur.
Does compressing change the text?
No. Text stays real text at every setting. Only pictures, including scanned pages, are made smaller.
Is it safe to upload my documents?
Your PDF travels over an encrypted connection, the working copy is deleted before your download begins, and nothing is kept. No account is needed.
Can I reduce PDF size to 100 KB without losing quality?
Text never loses anything, because it is not turned into a picture. Scanned pages in black and white often look cleaner than the original, since the grey paper tint and scanner noise disappear. Photos do get softer at 100 KB; if the form allows more, use a larger target.
Can I aim for 200 KB instead?
Yes. Pick Under 200 KB in the tool, or use the Compress PDF to 200 KB page, which keeps more detail when the form allows it.
Last updated September 2026 · Written and maintained by the FlipMyFormat team