How to Reduce a Scanned PDF to 200 KB Without Making It Unreadable
A scan is a picture of a page. Making it smaller means choosing how much of that picture to keep.
Why scanned PDFs are so large
A PDF made from a scan or a phone photo does not contain text. It contains an image of each page. A single A4 page scanned at 300 DPI in colour is about 2480 x 3508 pixels, which is more than 8.7 million pixels and about 26 MB before compression. Even after the scanner's own compression, one page is commonly in the megabytes. A portal limit of 200 KB per document means the picture has to carry about one-tenth or less of that detail.
The good news is that a certificate or marksheet is mostly white paper and black text. It compresses far better than a photograph, provided you reduce the right things.
The four levers, in order of how much they help
| Lever | Effect on size | Effect on readability |
|---|---|---|
| Fewer pages | Very large | None. Send only the pages the form asks for. |
| Lower resolution (300 to 150 DPI) | Large: pixels fall by 75 percent | Small for printed text, as long as the text is not tiny. |
| Greyscale instead of colour | Moderate | None for black text; keep colour if a stamp or seal must stay red or blue. |
| JPEG quality inside the PDF | Large at first, then small | Fine down to a point, then text edges turn fuzzy. |
Note the order. Removing pages costs nothing, so do it first. Reducing resolution is almost always safe for normal printed text. Only then lower the quality, and stop as soon as the file fits.
A realistic method
- Scan or photograph the page properly. Flat paper, even light, straight from above. See phone scanning tips. A clean source compresses much better than a crooked, shadowed one.
- Crop to the page. Large dark borders around the paper are wasted bytes.
- Set the limit the portal states (for example 200 KB) in the compressor, and let it choose the highest quality that fits.
- Open the result at 100 percent. Read the smallest text on the page, usually dates, roll numbers and percentages. If you can read it, an officer can.
- If it is too soft, raise the limit if the portal allows, or send fewer pages in that file and upload the rest separately.
Sensible targets by limit
| Portal limit | Typical approach for a one-page certificate |
|---|---|
| 100 KB | Greyscale, about 100 to 150 DPI equivalent, one page per file. Check small text carefully. |
| 200 KB | Greyscale or light colour, about 150 DPI equivalent. The most common comfortable target. |
| 300 to 500 KB | Colour at about 150 to 200 DPI equivalent. Good for pages with seals, photos or signatures. |
These are starting points, not guarantees: dense pages with small print or a coloured background need more bytes than a clean certificate.
What not to do
- Do not shrink a PDF by printing it to PDF repeatedly. Each pass adds artefacts.
- Do not use tiny text sizes to fit more on a page. Compression hits small text first.
- Do not upload a photograph of a screen. Moire patterns are hard to compress and hard to read.
- Do not remove a page the portal explicitly requires, such as the reverse side of an ID.
Need to combine several documents first? Read how to combine certificates into one PDF.
Frequently asked questions
Why is my PDF still large after compression?
Because it has many pages, or the pages are dense photographs rather than text. Check the page count and remove pages the form does not need. If the tool says the PDF contains selectable text and no embedded page images, the file is already stored compactly and an image compressor cannot shrink it further.
Will compression change the text in my PDF?
For a scanned document the text is part of the picture, so heavy compression makes the letters softer. That is why you should read the smallest text on the result before uploading. For a text-based PDF, an image compressor leaves the text as it is.
Is it better to send one PDF or several?
Follow the form. If it has separate slots, upload each document in its own slot. If it asks for a single file, combine them in the order the notice lists. See combining documents into one PDF.
Can I compress a PDF on my phone?
Yes. Browser-based tools like the ApplyReady compressor run on a phone. Large files take longer on an older phone, so close other apps and keep the screen on while it works.
What resolution should I scan at?
For printed text, 150 DPI equivalent is usually enough for reading, and 200 to 300 DPI helps for small print or stamps. Higher is not better if the file must stay under a small limit.
Does the compressor upload my certificates?
No. The processing runs in your browser and your files are not sent to a server. You can test this yourself with the airplane-mode check in the guide on staying safe with document uploads.