How to reduce a PDF to 100 KB or 200 KB for a government portal, and keep it readable

The short answer. Open a PDF compressor that takes a target size, set it to 100 KB or 200 KB, and download the result. A one-page scan reaches 100 KB easily; a five-page scan has only 20 KB a page and turns blurry. If it won't fit, remove pages you don't need, rescan at 150 DPI in greyscale, or split the file.

Portals for exams, scholarships, visas, admissions and government jobs set a hard upload limit, often between 100 KB and 500 KB, because they store millions of files. A phone scan of one certificate is usually 1 to 5 MB. The gap is big, but it is almost entirely made of picture detail the portal never needed. This guide is also available in Hinglish: PDF ka size kaise kam kare.

Where the size comes from

A PDF made in Word or by a billing program stores real text, which is tiny: a 20-page typed report can be 150 KB. A scanned PDF stores a photograph of each page, and that is what makes it large. A colour A4 page scanned at 300 DPI is 2,480 × 3,508 pixels, almost 9 million pixels, and even as a JPEG that is commonly 1 to 2 MB.

Compression shrinks those pictures in three ways, in order of how much they save:

1. Resolution. Halving the DPI from 300 to 150 leaves a quarter of the pixels. A page at 150 DPI (1,240 × 1,754 pixels) is still perfectly readable on screen and in print.
2. Colour. A black-and-white certificate stored in full colour carries three channels of data where one would do. Greyscale alone often cuts the size by half or more.
3. JPEG quality. Lowering quality from 95 to about 70 is hard to see on a document and roughly halves the bytes again.

Text that is real text, fonts and lines are not pictures, so a good compressor leaves them alone and they stay sharp.

How many KB each page gets

The limit is for the whole file, so divide it by the number of pages:

Limit	1 page	2 pages	3 pages	5 pages	10 pages
100 KB	100 KB, easy	50 KB, fine	33 KB, fine	20 KB, small print starts to blur	10 KB, hard to read
200 KB	easy	easy	66 KB, fine	40 KB, fine	20 KB, small print starts to blur
500 KB	easy	easy	easy	100 KB, easy	50 KB, fine

As a rule of thumb from scans of ordinary A4 certificates and mark sheets, a page stays comfortably readable down to about 30 to 40 KB. Below about 20 KB a page, small print, stamps and signatures start to smudge, which is exactly what a verifier looks at.

How to compress a PDF to 100 KB or 200 KB

1. Open Compress PDF set to 100 KB or Compress PDF set to 200 KB, or Compress PDF and type your own target.
2. Add the file. If it is password-protected, type the password when asked; the compressed copy is saved without it.
3. Run it. The tool tries lighter settings first and keeps the best-looking result that fits the target. You see the size before and after.
4. Open the result and zoom to 100%. Read the smallest text on the page, the registration number and the stamp. If you can read them, the portal's verifier can.
5. Upload. If the portal also sets a minimum, often 10 or 20 KB, a one-page file that came out very small may need a lighter setting.

A worked example

A student has a three-page mark sheet scanned on a phone at 3.8 MB, and the portal allows 200 KB.

• 200 KB across 3 pages is about 66 KB a page, comfortably readable.
• Target mode brings the file to around 190 KB at 150 DPI with no visible loss.
• The same file to 100 KB would be 33 KB a page: still fine for printed text, slightly soft on a faint rubber stamp.

If the portal had asked for 100 KB and the document were ten pages, the honest answer is that 10 KB a page will not stay readable. Upload only the pages the form actually asks for.

When it still won't fit

Work down this list; each step helps more than compressing harder.

1. Remove pages the portal does not need. Instructions pages, blank backs and duplicate copies are common. Organize PDF deletes and reorders pages.
2. Rescan, don't recompress. Scan at 150 DPI in greyscale (or "document" mode in a scanner app) and you start at a few hundred KB instead of several MB. A file that has been compressed hard twice looks worse than one scanned sensibly once.
3. Crop the margins. A phone photo of a page often includes the table under it. Cropping before making the PDF saves pixels for the document itself.
4. Split the file. If the portal has separate upload slots, Split PDF turns one long file into one PDF per document.
5. Ask whether a different document will do. A digitally issued certificate from DigiLocker or the issuing board is a text PDF, usually far smaller than a scan of the printed copy.

Check the portal's own notice

The limit, the minimum and the format are set by each portal, and they change between years. The application notice or the upload page states them; read it before compressing. For example, the Indian e-Visa portal's document upload asks for PDFs of at least 10 KB and at most 500 KB. Some portals want each document as its own file, some want them merged into one; Merge PDF joins them.

If it doesn't work

• "Could not reach the target." The tool tells you the smallest size it reached. The file has too many pages or very detailed images for that limit; remove pages or rescan as above.
• The file barely shrank. It is probably a text PDF already, or its images are stored as black-and-white fax data, which is already compact. Removing pages is the only way to make it much smaller.
• The portal rejects a file that is under the limit. Check whether the limit is in KB of 1,000 or 1,024 bytes; aim 5 per cent under to be safe. Also check the minimum size and that the name ends in .pdf.
• The text turned blurry. The KB per page is too low. Use fewer pages, or a higher target if the portal allows it.
• The portal says the file is encrypted or damaged. It still has a password or a signature restriction. Remove the password with Unlock PDF and compress again.

Questions people ask

How do I reduce PDF size to 100 KB?

Use a compressor with a target-size setting, enter 100 KB and let it lower the image resolution and quality until the file fits. One or two scanned pages reach 100 KB with no visible loss. For more pages, remove the ones the portal does not need first, because 100 KB across five pages leaves only 20 KB for each.

Why is my scanned PDF so large?

A scanned PDF holds a photograph of every page rather than text. A colour A4 page at 300 DPI is almost 9 million pixels, commonly 1 to 2 MB even compressed. Scanning at 150 DPI in greyscale produces a file several times smaller, and it is still sharp enough for any portal.

Can I compress a PDF without losing quality?

Partly. Lowering the resolution of a scan from 300 to 150 DPI and switching to greyscale shrinks it a lot with no difference you can see on screen. Squeezing several pages into 100 KB does lose detail, starting with small print and stamps. Real text in a PDF is never blurred by compression, because only pictures are re-encoded.

Is it safe to compress a marksheet or Aadhaar PDF online?

Only if the tool runs in your browser. Many compressor sites upload your file to their server. The compressor here works on your device: the PDF is never uploaded, so a mark sheet, an Aadhaar card or a bank statement stays private, and the tool keeps working with the internet switched off after the page loads.

What DPI should I scan documents at for online forms?

Scan at 150 DPI in greyscale for most certificates, mark sheets and ID cards. That is 1,240 by 1,754 pixels for an A4 page, clear on screen and in print, and usually a few hundred KB. Use 200 to 300 DPI only for documents with very small print, and colour only when the form asks for it.

Sources

Checked 5 Oct 2026:

• Government of India, Indian e-Visa: Document Upload (PDF minimum 10 KB, maximum 500 KB)
• Pixel sizes for A4 (210 × 297 mm) are calculated as millimetres ÷ 25.4 × DPI.