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How to Compress a PDF to 100 KB or 200 KB for Online Forms
By Quick Work Studio · Published 29 October 2026 · How we check facts
Government job portals, university admissions and scholarship forms often accept a PDF only up to a fixed size: 100 KB, 200 KB, 500 KB or 1 MB. A PDF made from phone photos is usually several MB, so the upload fails. This guide explains why the file is big and how to bring it under the limit without making it unreadable.
Why is my PDF so big?
A PDF is only a container. What makes it heavy is what's inside it:
- Photos of pages. A modern phone camera takes pictures of 12 megapixels or more. Each page of a "scanned" PDF is one of those photos, often 1 to 3 MB on its own.
- Typed text. A PDF saved from Word or Google Docs stores text as letters, not pictures. Ten pages of plain text can be under 100 KB already.
- Embedded fonts and images. Brochures and reports with large pictures sit somewhere in between.
So compression helps most with scans and photos. If your PDF is mostly typed text and still too big, the cause is usually one or two large images inside it.
How much space does each page need?
Compressing a scan means saving each page as a smaller picture. At a resolution that is still easy to read on screen, an A4 page of text usually needs somewhere between 40 and 120 KB, depending on how busy the page is. That gives a rough rule:
| Upload limit | Pages that usually fit | Level to try first |
|---|---|---|
| 100 KB | 1, sometimes 2 | Strong |
| 200 KB | 2 to 3 | Strong |
| 500 KB | 4 to 8 | Medium |
| 1 MB | 8 to 15 | Medium or Light |
If the form wants a 6-page document under 100 KB, no tool can do that while keeping it readable. In that case, check whether the form really needs every page (often it needs only the first page or the page with your result), or whether it allows several uploads.
Step by step on your phone
- Open the Compress PDF tool and choose your file.
- Pick Medium and tap Compress. You'll see the size before and after.
- If it is still over the limit, go back and pick Strong.
- Open the new file and zoom in on the smallest print, such as a roll number or date. If you can read it comfortably, it's ready to upload.
The file never leaves your phone. Compression happens inside your browser, which matters for marksheets, ID cards and bank documents.
When it still won't fit
- Remove pages you don't need. Use Split PDF to keep only the required pages, then compress the smaller file.
- Retake the photos. Shadows, a patterned background and grainy low light all make pictures bigger. A sharp photo of a page on a plain surface in daylight compresses far better.
- Crop the borders first. If you're building the PDF from photos, crop away the table and the edges with the Image Cropper before making the PDF.
- Make the PDF from smaller images. Run the photos through the Image Compressor first, then combine them with Image to PDF.
- Split it into parts if the form allows more than one upload, such as "Marksheet part 1" and "part 2".
What changes when a PDF is compressed this way
To shrink scans, each page is redrawn as a JPG picture at a lower resolution: about 150 DPI on Light, 110 on Medium and 80 on Strong. For documents that were already photos, you won't notice a difference except the size. For PDFs with typed text, the text becomes part of a picture, so you can't select or search it, and links stop working. That is fine for uploading to a form, but keep the original file for everything else.
If the result would be bigger than the original, which happens with plain text PDFs, the tool tells you to keep the original instead.
Common upload errors
| Message | What it usually means |
|---|---|
| File size exceeds limit | Compress again on a stronger level, or remove pages. |
| Invalid file format | The form wants a PDF but you picked a JPG, or the other way round. Use Image to PDF or PDF to JPG. |
| File is corrupted or can't be read | The upload was interrupted, or the PDF is password-protected. Save an unlocked copy and try again. |
| File too small | Rare for PDFs; a few forms set a minimum. Use a lighter level. |
A quick checklist
- The file is under the limit, ideally with a little room to spare (190 KB for a 200 KB limit).
- Every page is the right way up and in the right order.
- Small print is still readable when you zoom in.
- The file name is simple, like marksheet-12.pdf, without symbols. Some portals reject names with spaces or brackets.
Try it: Compress PDF shrinks the file on your phone with three levels. To work on images before they become a PDF, use the Image Compressor, and to reach exact sizes for photos and signatures, the Exam Photo & Signature Resizer.