Compress a PDF under 100 KB or 200 KB for a government portal

By Aman, founder of FABX Labs · Updated 17 September 2026 · 5 min read

GST wants 100 KB, NSP 200 KB, NTA between 50 and 300 KB. How to get a scanned certificate or bill under the limit and still readable, when to split instead of compress, and why you should never compress a digitally signed PDF.

Government portals are strict about document size, and the limits are small. A single-page electricity bill scanned at a copy shop is often around 400 KB. A rent agreement photographed on a phone can be several MB. The portal wants 100 KB.

Getting under the limit is easy. Getting under the limit with the document still readable is what matters, because a person checks it, and an unreadable certificate is sent back.

Common limits

These are the caps commonly reported for recent forms. The number shown on the upload screen you are using always wins.

The right order: colour first, sharpness last

A scanned page is really a picture of the page. There are three ways to make that picture smaller, and the order you try them in decides whether the text stays readable:

1. Drop colour you don't need. Most bills, certificates and agreements are black text on white paper. Greyscale keeps stamps and signatures visible at a fraction of the size.
2. Use black and white for plain typed pages. Each dot becomes pure black or pure white, which stores very compactly. Text stays crisp at a higher resolution than colour could afford at the same size.
3. Only then lower the resolution, and only as far as the limit needs.

Cheap online compressors often do the reverse and go straight to low resolution. That blurs the certificate number and the officer's stamp, the two things a verifying officer looks for.

GST: the tightest common limit

The GST registration form allows 100 KB per document, and a rent agreement can run to three to eight pages. That leaves 12–30 KB per page, too little for colour.

• Try black and white first. Typed agreements usually fit.
• If it still won't fit, upload the pages the officer needs: the first page, the page with the address, and the signature page. Keep the full copy ready in case they ask for it.

NTA: when a file is too small

NTA forms take certificates as PDFs between 50 and 300 KB. A clean certificate from DigiLocker can be about 30 KB, and the portal rejects it for being too small.

Re-scanning at a higher resolution to fix this changes the document and can make it worse. The better fix adds an unused block of empty data inside the PDF. The file grows into the range, every PDF viewer shows exactly the same page, and the text is untouched.

When to split instead of compress

For bigger limits (2 MB, 5 MB, 6 MB), the problem is usually a long document, not a heavy page.

• A bank statement or ledger downloaded as a PDF is text. Turning it into images to hit a limit makes it blurry and unsearchable. Split it into parts under the limit instead, and name the parts so the officer can follow them (Annexure A, part 1 of 3).
• A scanned document is already images, so compressing it is fine.
• If a PDF is already under the limit, upload it as it is. Compressing never improves a file.

Never compress a digitally signed PDF

If a PDF carries a digital signature (a DSC), any tool that rewrites the file breaks the signature. This matters most for MCA and income-tax filings.

• Compress first, then sign. Leave some margin: for a 6 MB limit, aim for about 5.5 MB before signing, because the signature adds size.
• If a signed PDF is already over the limit, compress the unsigned original and sign again, or split the unsigned original and sign each part.

Phone photos of documents

If you only have a photo of the document:

• Lay the page flat, in daylight, filling the frame.
• Avoid shadows from your hand and phone. Shadows make the file bigger and the text harder to read.
• Select all the pages together to make one PDF, rather than uploading pages as separate files.

Quick answers

Will the text still be selectable?

For a digital PDF that already fits, yes, because it is returned unchanged. A compressed scan is an image of the page, as the original scan already was.

Is it safe for client documents?

The PDF is processed on your own device and never uploaded. You can switch off the internet after the page loads and it still works.

The portal still says my file is too large.

Check the number on the upload screen, which may differ from the commonly reported one, and enter that as the limit.

Tools used in this guide

More guides

• UPSC: the photo, the triple signature and the 10-day rule
• Form 16, ITR-V and bank statements: finding the PDF password you already have
• SSC photo and signature rules, explained
• Split a large PDF to fit a 5 MB or 10 MB limit