Why so many forms ask for a PDF under 100 KB
Government portals, university admissions, scholarship sites and job applications often cap each upload at 100 KB, because they receive thousands of documents a day. A single scanned page from a phone or office scanner is usually 300 KB to 3 MB, so it gets rejected. This page opens our PDF compressor with the target already set to 100 KB. Pick your file and press the button: it first tries to shrink the PDF while keeping its text, and if that isn't enough it re-draws the pages as images at the highest sharpness that still fits under 100 KB. Nothing is uploaded; the work happens on your own phone or computer.
Updated September 2026
How to compress a PDF to 100KB
- 1Tap Select PDF file and choose the document you need to upload.
- 2Check that the target says 100 KB (you can type a different number if your form allows more).
- 3Press Compress PDF and wait while the progress bar runs; each try goes through every page.
- 4When it says “under 100 KB”, download the file and upload it to your form.
What fits in 100 KB
As a rough guide, a text-heavy A4 page saved as an image needs 25–60 KB to stay readable, and a colour photo page needs more. So a 100 KB limit suits a certificate, a mark sheet, an ID card (front and back) or a short letter. For longer documents, check whether the form lets you upload several files, and send them as separate parts.
Scanning tips for a clean result under 100 KB
- Scan or photograph only the paper itself; dark table edges and shadows waste bytes.
- Use good, even light so the page background comes out white rather than grey.
- Straighten the page before scanning; a tilted page looks worse after compression.
- If your scanner app has a “document” or “black and white” mode, use it for text-only pages.
- Combine phone photos into a PDF with JPG to PDF, then compress it here.
What the tool does, step by step
First it checks whether your file is already under 100 KB; if so, you can use it as it is. Next it rebuilds the PDF's internal structure more compactly, which keeps the text sharp and selectable. If the file is still too big, it renders each page to a JPEG picture and searches through 17 settings, from 150 dots per inch at high quality down to 50 dots per inch, to find the sharpest one that fits. It halves the range with every try, so about five tries are enough, and for documents longer than four pages those tries run on four sample pages before the whole file is compressed once.
On a phone
The whole process runs in your phone's browser, so you can compress a PDF you just received on WhatsApp or email without installing an app. Keep the screen on and the page open while the progress bar runs, then use the download button and pick the file from your Downloads or Files app when the form asks for it.
Features
- Target preset to 100 KB
- Tries a text-preserving squeeze before turning pages into images
- Chooses the sharpest setting that still fits
- Clear message and smallest possible file when 100 KB can't be reached
- Progress bar showing each try and page
- Private: the PDF stays on your device
Frequently asked questions
Can every PDF be made smaller than 100 KB?
Not always. One or two scanned pages usually fit well, and three can fit at a lower resolution. A document with ten or more full pages of photos or colour scans may become too blurry to read at 100 KB, so the tool stops at its lowest readable setting and tells you the smallest size it reached.
Will the text in my PDF still be selectable?
If the lighter, text-keeping method alone gets under 100 KB, yes, and the result says so. If not, the pages are saved as pictures, which look the same on screen and print but can't be searched or copied.
My form says “maximum 100 KB”. Is 100 KB the same as 100,000 bytes?
Here 100 KB means 100,000 bytes. Some websites count 1 KB as 1,024 bytes and others as 1,000, so the tool aims for the smaller number and the file fits either way. Your computer may show it as about 97 KB.
Why does it take longer than normal compression?
To hit an exact size the tool has to test several settings (on a few sample pages when the file is long) before it compresses the whole PDF with the best one. For a short document that takes seconds; a long one on an older phone can take a minute or two.
The result is still over 100 KB. What can I do?
Upload only the pages the form asks for: remove extra pages with Delete PDF Pages, or cut a long file into parts with Split PDF, then compress each part here. A tighter scan (just the document, not the table around it) also helps a lot.
Is it safe to compress ID cards and certificates here?
Yes. Your PDF is processed inside your browser and is never sent to our servers or anyone else, so identity documents and certificates stay private.