How to Compress a PDF to a Specific Size (100 KB, 500 KB, 2 MB)

Visa applications, tax portals, university uploads, and job sites don’t just ask for a PDF — they cap it at an exact size. “Maximum file size: 100 KB.” “Upload must be under 2 MB.” A 6 MB scan gets rejected with no advice on how to shrink it. This is how to get a PDF under a hard limit without dropping content you actually need.

First, figure out where the size is coming from

A PDF’s weight almost always comes from embedded images, not text. That single fact decides which method will work:

• A scanned document (photos of pages) is nothing but images — it compresses dramatically, often 40–70% in one pass.
• A report with a few embedded photos or screenshots compresses moderately.
• A text-only PDF (a contract, an invoice, an ebook) is already small. If one of those is somehow over a limit, the problem is usually page count, not compression.

Open the PDF and try to highlight a sentence with your cursor. If the text selects, there’s a real text layer and it’s staying sharp no matter what you do. If nothing selects, it’s a scan — an image of each page.

The fastest route: compress, then check

1. Run the PDF through a PDF compressor. It re-encodes the embedded images at an efficient quality and resolution and strips metadata the file doesn’t need. Text and vector graphics are untouched.
2. Open the result and check the file size. For a scanned document this single pass is often enough to clear a 500 KB or 1 MB limit outright.
3. If it’s still over, keep reading — the next steps stack on top.

Getting under a very tight limit (100 KB or less)

A 100 KB cap on a multi-page scan is aggressive. Combine these:

• Reduce the page count. If the form only needs pages 2 and 5, don’t upload all ten. Split the PDF and keep just what’s required — fewer pages is the biggest lever there is.
• Compress the images before rebuilding. If one or two enormous photos are the problem, pull them out, run each through Compress Image with an exact KB target, and reassemble. Compress Image lets you name a size and hits it; the PDF compressor applies one efficient pass rather than targeting a number.
• Scan smarter next time. If you control the scan, scan in greyscale (not colour) at 200 DPI rather than 600. A greyscale 200 DPI scan of a text document is a fraction of the size and still perfectly legible.

Common size limits and what usually clears them

Limit	Typical fix
2 MB	One compression pass clears almost any normal document
1 MB	One pass for scans; one pass plus trimming pages for longer files
500 KB	Compress, then drop pages you don’t need
200 KB	Compress + greyscale + only the required pages
100 KB	All of the above, and compress the individual images to an exact size first

What compression won’t do

It won’t target an exact kilobyte figure on its own — it applies one sensible pass. And it won’t shrink a text-only PDF much, because there’s very little to remove. If you’re stuck, the two highest-impact moves are almost always removing pages you don’t need and compressing the largest embedded images separately before putting the document back together.

Once you’ve got a version under the limit, open it one more time before uploading to confirm the pages are still readable — a scan crushed too hard to fit 100 KB isn’t worth submitting if the reviewer can’t read it.