How to compress a PDF to 500 KB
- Tap Choose PDF above and pick your file (or drop it on the box).
- The Target size (KB) is already 500. Change it if your portal states a different limit.
- Tap Compress PDF. The gauge shows the result against your limit; most files take a few seconds.
- Tap Download compressed PDF. Open it and check every page is readable before you upload it.
What fits in 500 KB: measured
| Document | Original | At 500 KB | Images kept at |
|---|---|---|---|
| 2-page phone scan | 6.34 MB | 458 KB | 1707 px |
| Fillable form with a photo (4 fields) | 3.18 MB | 496 KB | 2302 px |
| 2-page letter printed from Chrome, with a photo | 2.56 MB | 418 KB | 2136 px |
| Colourful certificate scan | 1.82 MB | 420 KB | 2136 px |
| 10-page phone scan | 34.12 MB | 477 KB | 751 px |
Test files: the documents above, made by us from phone photos and printed pages (the form has four fillable fields). Desktop Chromium on our test server, 27 October 2026; each took under 6 seconds. "Images kept at" is the long side of the page images after compressing. Every result kept its text and form fields. Sizes in decimal units (1 KB = 1,000 bytes), as the tool shows them.
At 1700–2300 pixels, scanned pages look essentially like the original on screen; for printing, 2302 pixels is about 200 DPI on an A4 page, 1707 about 150 DPI, fine for typed text. Even our 10-page, 34 MB scan fitted, at 751 pixels per page: readable at normal print size. For a limit this generous you rarely need to remove pages or switch to greyscale.
Going higher: 1 MB
If the portal allows more, type a bigger number. At 1000 KB (1 MB) our 2-page scan kept 2302 pixels and the 10-page scan 1091. Files with one embedded photo stopped well below 1 MB (634–651 KB): PixKB's best setting keeps images at up to 2480 pixels (an A4 page at 300 DPI) in high quality, and once a file fits at that setting it stops there.
500 KB for email
If you're emailing rather than uploading, 500 KB sends quickly on slow connections and fits comfortably in any inbox. Email services allow far more (about 20–25 MB per message), so there's no hard limit to meet; see email attachment limits.
Already under 500 KB?
If your PDF is already under the limit, PixKB doesn't touch it: you get the original file back, unchanged.
Common mistakes
- Including pages the portal didn't ask for. A blank back side or an extra copy halves every other page's share of the limit.
- Not cropping scans. A table edge or the background around the paper uses part of the limit. Scanner apps crop automatically; see scanning a document for upload.
- Compressing an already-compressed copy again. Start from the original PDF each time you try a different limit.
- Uploading without checking. Open the result and zoom in on the smallest print before you submit.
- Splitting the limit wrong. If the portal has one limit for several uploads, check whether it applies per file or to all files together.
1,000 or 1,024 bytes?
Portals count a kilobyte either way. PixKB keeps the file at or under 500,000 bytes, so it passes a 500 KB limit whichever way the portal counts.
Frequently asked questions
Is 500 KB enough for a 10-page scanned document?
Yes, in our test: a 34 MB 10-page phone scan came out at 477 KB with 751-pixel pages, readable at normal print size.
Does the tool reduce quality more than necessary?
No. It tries settings from best to smallest and keeps the first that fits, so you get the sharpest file under 500 KB.
Why did my PDF come out well under the limit?
PixKB's best setting keeps images at up to 2480 pixels (an A4 page at 300 DPI) in high quality. If the file fits at that setting, it stops there, below the limit.
Can I go lower than 500 KB here?
Yes, type a smaller number, or use the 200 KB and 100 KB pages.
Will fillable form fields still work?
Yes. Only images are recompressed; fields, text and links are copied unchanged.
Are my files uploaded?
No. Compression happens entirely in your browser.