Will every PDF end up under 300 KB?

No. The tool lowers image quality level by level until the file fits, then returns the smallest result it reached. A file with little image content, or with image types that are skipped, can stay above the target.

Is 300 KB 300,000 bytes or 307,200?

The preset counts 1 KB as 1,024 bytes, so the target is at most 307,200 bytes. A portal that counts 1 KB as 1,000 bytes accepts 300,000, so a result between the two sizes could be refused. Type a lower value, such as 0.28, in the target field.

Does the text stay selectable?

Yes. Text, fonts and vector art are never changed. Image-only scans remain images.

What happens if my file is already under the limit?

It comes back with only the qpdf optimization applied and the content unchanged.

Can I use a different size?

Yes. Type any value from 0.05 to 1024 MB in the target field; the preset only saves you the typing.

Shrink a PDF to 300 KB or Less

Compress PDF to 300 KB repacks a PDF with qpdf and lowers image quality level by level until the file fits under 300 KB. If it cannot, you get the smallest result reached.

Drag and drop files here, or click to choose

Accepts PDF · up to 500.0 MB per file · up to 20 files at once

You can also paste a file with Ctrl/Cmd+V, or from the clipboard menu.

Target size in MB (optional)Leave empty for standard compression. Enter 1 to shrink the file to under 1 MB; the tool lowers image quality step by step until it fits.

Keep recent files in this browser (up to 5, 50.0 MB in total, never uploaded)

A 300 KB cap sits between the 200 KB and 500 KB limits that application forms, job portals and ticket systems often set. It is realistic for a few pages of photos or scans, and not for a long scan or a file that is heavy because of fonts.

The target field is already filled with 0.292 MB. In this tool 1 MB is 1,048,576 bytes, so 0.292 MB sits just under 300 KB. The tool first repacks the file with qpdf, then re-encodes page images as JPEG through up to seven levels, from quality 75 and a 2000 px longest side down to quality 18 and 450 px, and stops at the first result that fits.

The tool works on the images, not on text: JPEG and 8-bit RGB or Gray images are re-encoded through up to seven levels, and everything else is left as it is. The more pages carry photographs, the less room each page has inside 300 KB, so a few pages can fit where a long scan stops short.

Measured on freely licensed documents, the result depends on what the pages hold. Photographed JPEG pages shrink: a 32-page album went from 11.43 MB to 304.1 KB, the smallest it could make with a 300 KB target. Text and vector documents hardly change: a 15-page research paper went from 2.11 MB to 1.62 MB, the smallest it could make. Scans stored as JPEG 2000 or JBIG2 images, as many archive scans are, are skipped: a 38-page archive scan went from 2.23 MB to 2.22 MB, the smallest it could make. The table below lists every document.

The target is a goal, not a guarantee. If even the strongest level does not fit, you get the smallest result it reached, and the page count, page size, text and fonts are never changed. Image-only scans stay images, and 1-bit, CMYK, indexed, masked and transparent images are skipped, so a scan stored that way barely shrinks.

Image re-encoding is lossy. Open a few pages of the result before you send it, and keep the original. If a portal enforces a hard limit that the file cannot reach, Split by Page Count with By file size sends it in parts that each fit.

What happens at 300 KB: measured results

Document	Pages	Original	Result	Under 300 KB?
Attention Is All You Need (arXiv 1706.03762) (CC BY 4.0)	15	2.11 MB	1.62 MB	No
IRS Form 1040 (Public domain, US government)	2	215.1 KB	192.9 KB	Already under
Expedition 71 Crew Poster Brochure (NASA) (Public domain, NASA)	2	7.21 MB	272.6 KB	Yes
Album Or. 27.399, page 1 (Leiden University Libraries) (CC BY 4.0)	1	475.9 KB	178.5 KB	Yes
Album Or. 27.399, pages 1-5 (Leiden University Libraries) (CC BY 4.0)	5	1.41 MB	200.2 KB	Yes
Album Or. 27.399 (Leiden University Libraries) (CC BY 4.0)	32	11.43 MB	304.1 KB	No
Field letter (Internet Archive scan) (Public domain)	38	2.23 MB	2.22 MB	No

Measured on 2026-10-23 with this service's release build on freely licensed PDFs. KB and MB are 1,024 and 1,048,576 bytes. "Already under" means the original fit, so only the qpdf step ran. "No" rows show the smallest result the tool reached.

Features

Target size preset to 0.292 MB (300 KB)
Seven image levels, JPEG quality 75 down to 18, longest side 2000 down to 450 px; stops at the first that fits
Page count, page size, text, fonts and vector art stay unchanged
Returns the smallest result reached if the target cannot be met
Anonymous API at /api/v1/misc/compress-pdf with targetSizeMb

When to use this tool

Upload a scanned ID or certificate page to a portal with a 300 KB cap
Shrink a short photographed document for a web form
Send a photo-heavy one-pager through a size-limited ticket system

How do I compress a PDF to 300 KB?

Upload the PDF that is over the limit.
Leave the target size at 0.292 MB, or change it if the limit is different.
Click Process and download the result.
Check the file size against 300 KB and open a few pages to judge image quality.

Limits and edge cases

The target is a goal; the smallest result reached is returned
Strong levels make photos visibly softer
1-bit scans, CMYK, indexed, masked and transparent images are skipped
Does not subset fonts or convert color spaces
Password-protected files need the password first

Privacy for this tool

Files are uploaded over HTTPS, processed in memory or a short-lived temporary directory on our servers, and deleted when your result is ready. We do not keep copies for later browsing, training, or advertising profiles. See the Privacy Policy for retention details and AdSense cookie disclosures.

Frequently asked questions

Will every PDF end up under 300 KB?: No. The tool lowers image quality level by level until the file fits, then returns the smallest result it reached. A file with little image content, or with image types that are skipped, can stay above the target.
Is 300 KB 300,000 bytes or 307,200?: The preset counts 1 KB as 1,024 bytes, so the target is at most 307,200 bytes. A portal that counts 1 KB as 1,000 bytes accepts 300,000, so a result between the two sizes could be refused. Type a lower value, such as 0.28, in the target field.
Does the text stay selectable?: Yes. Text, fonts and vector art are never changed. Image-only scans remain images.
What happens if my file is already under the limit?: It comes back with only the qpdf optimization applied and the content unchanged.
Can I use a different size?: Yes. Type any value from 0.05 to 1024 MB in the target field; the preset only saves you the typing.

Last updated: 2026-10-09

More ways to use Compress

Compress PDF to 100 KB - Set the target to 100 KB and let the tool try stronger image settings until it fits.
Compress PDF to 200 KB - Set the target to 200 KB and let the tool try stronger image settings until it fits.
Compress PDF to 500 KB - Set the target to 500 KB and let the tool try stronger image settings until it fits.
Compress PDF to 1 MB - Set the target to 1 MB and let the tool try stronger image settings until it fits.
Compress PDF to 2 MB - Set the target to 2 MB and let the tool try stronger image settings until it fits.
Compress PDF for Email - Size a PDF for an email attachment limit; the target is preset to 10 MB.
Reduce PDF Size, Keep Text Sharp - The mildest compression only: text and vectors untouched, images lightly recompressed.
Compress PDF to 5 MB - Aim for 5 MB: the target is already filled with 5.

Call this from code

Every tool on this site is a plain REST endpoint - no account or API key needed for anonymous use. Built for AI agents and developers as much as for browsers.

curl -X POST "https://pdf123.xyz/api/v1/misc/compress-pdf" \
  -F "[email protected]" \
  -o output.pdf

Also available as an MCP tool for agent clients that speak Model Context Protocol (JSON-RPC 2.0 over POST /mcp). Full API reference

Use it from an AI agent

Skill

Claude Code, Codex, Cursor and other AI agents can run Compress for you with this skill: /skills/pdf123-compress.md

All agent skills

Files are used only for this processing job and deleted automatically afterward.