How to Compress a PDF to 100 KB or 200 KB for Online Forms

By the DocEpic team · Updated 10 November 2026 · 4 min read

Certificates, mark sheets, caste and income certificates, ID proofs: online forms in India often want them as a PDF under 100 KB, 200 KB or 500 KB. A scanned page from a phone is usually 1 to 5 MB, so it has to shrink twenty or thirty times without becoming unreadable. Here is why PDFs get so big, how to bring one under a fixed size, and what to do when it still won't fit.

Why your PDF is so large

A PDF made from typed text is tiny — a few pages of a Word document are often under 100 KB already. The size comes from pictures. A scanned certificate or a photographed document is really one large photo per page, stored at full camera resolution, often in colour even when the paper is black and white.

So the two things that shrink a PDF the most are lowering the resolution of those page pictures and compressing them more strongly. Fonts and text hardly matter.

Compress to an exact size in three steps

Compress PDF to KB is made for exactly this: you choose the limit, and it finds the smallest change that gets under it. There are also ready-made pages for the common limits, such as Compress PDF to 100 KB and Compress PDF to 200 KB.

1. Open Compress PDF to KB and add your PDF.
2. Choose the limit: 100 KB, 200 KB, 300 KB, 500 KB, 1 MB or 2 MB, or type a custom size.
3. For certificates and other documents, tick Black and white if needed — it roughly halves the size at the same sharpness.
4. Click Compress and download. The result shows the new size, so you can check it is under the limit before uploading.

What happens to your file

The tool first compresses the PDF normally, the way a printer driver would, so text stays sharp and can still be selected and searched. This step runs on our server in a private temporary folder that is deleted as soon as the result is sent back.

If that isn't enough to reach your limit, the pages are redrawn as JPEG pictures in your browser, trying different resolutions and qualities until the file fills the limit as closely as possible. The text can then no longer be selected, but the page looks the same. Most portals only need the page to be readable, so this is fine for uploads — keep your original for printing.

Check that it is still readable

Before uploading, open the downloaded file and zoom in on the smallest text, such as a roll number or a date. If it is hard to read, try a larger limit if the form allows it, or tick Black and white, which keeps documents crisper at the same size than colour does.

When it won't fit

A long PDF has to share the limit between all its pages: ten pages in 100 KB leaves about 10 KB per page, which is too little for a scan. If the portal allows several uploads, split the document with Split PDF and upload the parts separately. If it wants only certain pages — often just the first page of a certificate — keep only those.

If you are scanning the document yourself, a better scan saves space. Scan to PDF uses your phone camera and saves the pages in grey or black and white, which gives a much smaller file to start from than a colour photo. Shoot from straight above, on a dark background, in good light. To combine several scans into one upload, use Merge PDF first and compress the result.

If the form only says the file must be small, without a number, plain Compress PDF with the Recommended level is usually enough and keeps the text selectable.

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