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How to make a PDF smaller than 10 MB

10 MB is the everyday upload cap — most email providers, Slack, many ticketing systems. Here is how to comfortably clear it in your browser, without uploading the file you are shrinking.

Open the Compress PDF tool →

10 MB is the unofficial “everyday upload” cap. Most ticketing tools, Slack, many corporate webmail filters, ATS resume parsers, and customer portals quietly enforce it. The good news: nearly any PDF can be shrunk under 10 MB with the “Recommended” preset, and you can do it in your browser, with no upload.

Where the 10 MB ceiling shows up

  • Slack: technically a 1 GB free-tier file limit, but big files hurt channel UX and are often blocked by org policy.
  • Zendesk, Freshdesk, and many other ticketing systems: the per-message attachment cap is usually 10 MB.
  • ATS / hiring platforms: Workday, Greenhouse, Lever often cap resume + portfolio uploads around 10 MB.
  • Corporate webmail filters: Gmail’s 25 MB cap is often re-imposed at 10 MB by company-level rules.
  • Many customer-portal “upload your invoice” fields.

The 30-second fix

Drop the PDF in. Pick Recommended. Hit compress. Check the result. That clears 10 MB for most PDFs that are not scan archives.

If you are still over:

  1. Step up to High. Drops image DPI further. Loses noticeable quality only if you print the result.
  2. Delete pages you do not need. Use the Delete Pages tool — blank scanned back-sides, marketing pages, terms-and-conditions appendices that the recipient is not going to read.
  3. Split, do not compress harder. If the file is genuinely 50 MB and full of necessary content, the Split PDF tool breaks it into smaller per-section files. Send them as separate attachments.

It runs the PDF through Ghostscript with image downsampling at roughly 150 DPI, JPEG re-encoding for color images, and lossless re-compression of vector and text content. Text stays selectable. Vector logos stay sharp. Images become smaller, but at print-acceptable quality.

If you specifically need a non-lossy output — say, archival scans — pick Low instead. The savings are smaller but everything is preserved bit-for-bit where possible.

Privacy

The contract, the deal memo, the medical scan you need under 10 MB to attach is exactly the kind of file you do not want sent through a third-party “online PDF compressor” that gets a copy of it first. Compression here is local. The PDF never leaves your device, and you can confirm in the Network tab.

Step by step

  1. Open the Compress PDF tool.
  2. Drop your PDF on the upload area.
  3. Start with "Recommended" compression — most files comfortably clear 10 MB this way.
  4. Click "Compress PDF" and check the before-and-after size.
  5. If still over, switch to "High" or drop pages you do not need.
Open the Compress PDF tool →

FAQs

Which compression preset should I pick to hit 10 MB?
Start with "Recommended". It downsamples embedded images to roughly 150 DPI, which keeps text crisp and produces a file that opens cleanly anywhere, and it is enough to get most PDFs under 10 MB. Switch to "High" only if Recommended leaves you over the limit.
Where does the 10 MB cap actually come from?
It is the soft consensus limit for everyday tools — most ticketing systems (Zendesk, Freshdesk), many ATS/HR systems, Slack file uploads, and some webmail providers all cluster around 10 MB. Gmail itself caps email attachments at 25 MB, but corporate IT filters often shave that down to 10.
My PDF is text-only and already small. Will compression do anything?
Probably not much. Recompression mostly squeezes embedded images. A 300-page text-only contract is usually under 1 MB already and cannot shrink much further. If you are over the cap with a text-only file, you may need to split or extract the relevant pages instead.
Is the file uploaded anywhere?
No. The compression engine (Ghostscript compiled to WebAssembly) runs inside your browser. Your PDF is shrunk locally on your device — you can confirm in the browser Network tab that the file is never uploaded.

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