How-to · Forms
Compress a PDF to 100 KB, 200 KB or 1 MB for online forms
Portal says the PDF is too big? What usually makes it big, the order to try things in, and what size to expect, all on your own device.
HarshFounder, DoYourPDF5 min read
To get a PDF under 100 KB, 200 KB or 1 MB, open it in a compressor, pick a stronger level until the size fits, and check that the text is still readable. If the strongest level is not enough, the file usually has too many pages for the limit: remove the pages the form doesn't need, or split it into parts. Compress PDF does all of this on your own device, so certificates and ID documents never leave your phone or computer.
Why the PDF is big in the first place
A PDF is usually big because of pictures. A page of typed text takes little space. A scanned page or a phone photo is a picture of the whole page, and when it becomes a PDF it keeps every pixel, so one photo from a modern phone can make a PDF of several megabytes on its own.
So the work is almost always the same: make the pictures in the file smaller without making the words in them unreadable.
Limits you'll meet
Every portal sets its own limit, and they vary a lot. Some examples from the portals' own pages:
| Where | What it accepts |
|---|---|
| Online Indian visa form (regular visa, not e-Visa) | PDF, 10 KB to 500 KB per document (Indian Visa Online) |
| INSPIRE Scholarship for Higher Education (SHE) | PDF, up to 1 MB per document (INSPIRE guidelines) |
| Income Tax e-Proceedings response | Up to 10 attachments, 5 MB each, 50 MB in all (Income Tax Department) |
| GST refund application | Up to 10 documents, 5 MB each, 50 MB in all (GSTN) |
Exam, job and scholarship forms state their limits in the notification or information bulletin for that year, and they change from one year to the next. Read the limit there rather than trusting a number from a website (including this one). Some forms also set a minimum size, like the visa form's 10 KB, so don't squeeze a file far below what's needed.
What to try, in order
- Compress at Strong. Open Compress PDF, choose Strong and press Compress. The result shows the size before and after. In my test below, a one-page photo of a letter came out well under 100 KB at Strong.
- Try Extreme if it's still too big. Extreme makes pictures smaller still, so small print can blur. Zoom in and check names, numbers and stamps before you upload.
- Drop pages the form doesn't need. A blank back side, an instructions page or a duplicate copy all cost space. Remove them with Remove Pages and compress again.
- Split it if the portal takes several files. Split by File Size packs pages into parts that each stay under a size you choose, down to 0.1 MB (about 100 KB), as long as no single page is bigger than that. Useful when a portal allows several uploads of 1 MB rather than one big file.
- Start again from the original if you have it. A clean PDF exported from the app that made the document is much smaller than a scan of a printout. Use the scan only when the original isn't available.
Starting from photos? Turn them into one PDF with Images to PDF, then compress that PDF. Images to PDF keeps each photo at full quality, so the first PDF will be large; the compression step is what brings it down.
What size to expect
To give you a realistic idea, I made a test image that looks like a phone photo of a typed one-page A4 letter (1.8 MB), turned it into a PDF with Images to PDF, and compressed it at each level. Then I did the same with three different photos of that kind, as three pages.
| Level | One page | Three pages |
|---|---|---|
| Before compressing | 1,853 KB | 5,559 KB |
| Recommended | 89 KB | 267 KB |
| Strong | 36 KB | 108 KB |
| Extreme | 22 KB | 65 KB |
Your files will differ: a photo with colour, shadows or a busy background comes out bigger than a clean page, and a carefully scanned page smaller. The pattern holds, though. Each page of a scan costs tens of kilobytes even at the strongest level, so a ten-page scan won't fit under 100 KB and stay readable. That is the point to remove pages or split.
The Also convert images to black & white switch removes colour from pictures. In the test above, where the page was already black text on white, it made almost no difference; it's worth a try on colourful pages.
Things that trip people up
- KB counted two ways. DoYourPDF, like Windows, counts 1 KB as 1,024 bytes; many websites count 1,000. A file shown as 199 KB is about 204,000 bytes, and a portal counting in thousands sees 204 KB. Aim about 10 percent under the limit.
- A digital signature stops validating. Any change to a signed PDF, compression included, breaks the signature. If the portal or the person receiving it checks the signature, upload the original if it fits, or ask what they accept.
- Typed text is not the problem. If your PDF has no pictures and is still large, it may carry big embedded fonts or many pages. Compress at Recommended first; the result will say if there was nothing to save.
Questions people ask
How do I compress a PDF to under 100 KB?
Open Compress PDF, choose Strong and compare the new size with the limit. If it is still too big, try Extreme, then remove pages the form does not need. A one-page scan usually fits; a long scan often won't fit in 100 KB at a readable quality.
Why is my PDF so big when it only has one page?
Almost always because the page is a photo or a scan. A phone photo turned into a PDF keeps every pixel of the photo, which can be several megabytes for a single page. Typed text takes very little space.
Will compressing make my document unreadable?
Text typed into the document stays sharp at every level, because only pictures are made smaller (unless you turn on Extreme's option to turn each page into a picture). Scanned pages are pictures, so at Strong and Extreme small print can blur. Zoom in on the result before you upload it.
The portal rejects my file even though it shows 99 KB. Why?
Some apps count 1 KB as 1,024 bytes and some websites count it as 1,000. A file shown as 99 KB on DoYourPDF is 101,376 bytes, which a portal counting in thousands sees as 101 KB. Aim about 10 percent under the limit.
Is it safe to compress certificates and ID documents online?
With Compress PDF the file is processed in your browser and never uploaded, so a marksheet, Aadhaar or bank statement stays on your device.