How it works
A PDF is a container: text and fonts, drawings, and embedded images. In almost every oversized PDF, the images are the weight: a single phone photo of a page can be 2–3 MB. PixKB opens the PDF in your browser, finds each photo or scan inside it, and re-encodes it at lower resolution and JPEG quality. It tries settings in order, measures the real file each time, and keeps the sharpest version that fits your limit. Text, fonts, links, bookmarks and form fields are copied over untouched.
What we measured
| Document | Original | Limit | Result | Images kept at |
|---|---|---|---|---|
| 2-page phone scan | 6.34 MB | 1 MB | 981 KB | 2302 px |
| 2-page phone scan | 6.34 MB | 300 KB | 265 KB | 1266 px |
| Fillable form + photo | 3.18 MB | 1 MB | 639 KB | 2480 px (full quality) |
| Fillable form + photo | 3.18 MB | 100 KB | 89.0 KB | 1012 px |
| Letter printed from Chrome | 2.56 MB | 150 KB | 149 KB | 1266 px |
Test files: a 2-page phone scan (6.34 MB), a fillable visa-style form with an embedded photo (3.18 MB, 4 form fields), and a 2-page letter printed to PDF from Chrome with a photo (2.56 MB). Desktop Chromium on our test server. Every result kept its text and form fields. Sizes in decimal units (1 KB = 1,000 bytes), as the tool shows them.
When text can't be kept
Some PDFs can't reach a small limit this way: a long report with no images (its size is text and fonts), or images stored in print colour formats (CMYK) that PixKB deliberately doesn't recompress to avoid colour shifts. Then PixKB tells you the smallest size it can reach with text intact and asks whether to rebuild the pages as images instead. That always reaches the limit, but text stops being selectable and form fields become flat. It's your choice, and the original file is never changed.
Getting a better result
Remove pages the portal didn't ask for before compressing: fewer pages leaves more of the budget for each one. Greyscale helps a little on colourful documents (in our test, about 8% more resolution at the same size) and barely at all on plain white paper. If you're combining several files, use merge PDF first, then compress the result. Photos that aren't a PDF yet can go through JPG to PDF, which has its own size limit.
Frequently asked questions
How do I compress a PDF to an exact KB size?
Choose your PDF, type the limit from your form (for example 200 for 200 KB) and press Compress. PixKB tries progressively smaller image settings and keeps the sharpest result under your number.
Will my text and form fields still work?
Yes, in normal compression only the photos and scans inside the PDF change. If text can't be kept within your limit, PixKB asks before rebuilding pages as images.
Is my document uploaded to a server?
No. The whole process runs in your browser. You can check it in your browser's network tab. It also works offline after your first compression, or after you tap Make this tool available offline.
Why didn't my text-only PDF get smaller?
Its size is text and fonts, which are already efficient. There are no images to shrink, so PixKB offers the page-image option only if you need a smaller file anyway.
How does PixKB count KB?
Strictly: 1 KB = 1,000 bytes. A file under your limit by PixKB's count passes portals that use 1,024 too.