How to compress a PDF to a specific size (100 KB, 200 KB, 500 KB or 1 MB)
Updated · PDF Converter
Government portals, job applications, university admissions and exam registration forms often accept PDFs only up to a fixed size – 100 KB, 200 KB, 500 KB or 1 MB are the usual limits. A normal scan or a phone photo saved as PDF is usually far bigger. This guide shows how to get under the limit in a minute, without installing anything.
The quick way: pick a target size
- Open Compress PDF and add your file.
- Under Compression, choose Target size.
- Pick the limit from the list – for example 200 KB.
- Press Compress and download the result. The file card shows the new size, so you can check it is under the limit before uploading.
If you already know your limit, the shortcut pages open with the target preselected: compress to 100 KB, 200 KB, 500 KB and 1 MB.
What happens behind the scenes
The tool first tries lossless optimisation, which removes duplicate data and tidies the file structure without changing how anything looks. If that is not enough, it re-encodes the images inside the PDF step by step – lower resolution and stronger JPEG compression each time – and stops at the first step that fits your target. That way you get the best quality that still meets the limit, not simply the smallest file.
Text and vector graphics are not touched in these steps, so letters stay sharp and you can still select and search the text.
When the file still will not fit
Very large scans can be too big even at the strongest image setting – for example a 30-page colour scan squeezed into 100 KB. You then have three options:
- Turn pages into images. Tick “Turn pages into images if needed”. Each page is flattened into a single compressed picture, which can go much smaller. The downside: the text is no longer selectable. For an upload form this rarely matters.
- Upload fewer pages. Many forms only need the first page or two. Use Split PDF or Extract Pages to keep just those pages, then compress.
- Scan again at lower settings. Grey-scale at 150–200 dpi is plenty for documents and starts out many times smaller than a colour 600 dpi scan. You can also convert an existing file with PDF to Black & White.
Which target should I choose?
| Limit | Typical use | What to expect |
|---|---|---|
| 100 KB | Exam and job portals, ID uploads | Fine for 1–3 pages of text; photos get noticeably softer |
| 200 KB | Application forms, certificates | Good for short scanned documents |
| 500 KB | Online forms, insurance claims | Most documents look unchanged |
| 1 MB | Email, visa and university portals | Even long scans usually fit with good quality |
Tip: if the form says “maximum 200 KB”, aim one step lower when you are close to the limit. Some portals count a kilobyte as 1,000 bytes instead of 1,024.
Is it safe to compress private documents?
Yes. The compression runs inside your browser, so your PDF is not uploaded to a server. That matters for ID cards, payslips, certificates and medical documents – the kind of files these forms usually ask for.
Frequently asked questions
Can I compress a PDF to an exact number of kilobytes?
The tool guarantees the file is at or below the size you pick, but not exactly that size. It is usually a little smaller, because it stops at the best-quality step that fits.
Why is my compressed file blurry?
A very small target forces strong image compression. Choose a larger target if the form allows it, or remove pages you do not need so the remaining ones keep more detail.
Does this work on a phone?
Yes. Open the page in your mobile browser, pick the file from your downloads or files app, and download the compressed PDF.