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Compress PDF Online — Reduce PDF Size Free

To compress a PDF, open it here, pick a target such as 100 KB or 200 KB, and tap Compress. In our tests, a 5.16 MB six-page scan came down to 69 KB in 2.1 seconds. Text stays sharp and the file is never uploaded.

  • Free
  • No signup
  • Files never leave your device

Up to 200 MB. Processed on your device.

How to compress a PDF

  1. 1Select or drop your PDF into the upload box.
  2. 2Choose Target size and tap a chip such as 100 KB or 200 KB, or switch to Quality level and pick Best quality, Balanced or Smallest size.
  3. 3Turn on Black & white if your PDF is a scanned document and colour is not required.
  4. 4Tap Compress and wait a few seconds; the first time, the compression engine (about 11 MB) downloads once.
  5. 5Check the new size shown on the result card and tap Download.
About Compress PDF: key facts and tips

Key facts

Documently Compress PDF is a free in-browser tool that reduces a PDF to a target size such as 50 KB, 100 KB, 200 KB, 500 KB or 1 MB. The compressor runs Ghostscript compiled to WebAssembly, so the PDF is processed on the phone or computer and is never uploaded. Typed text and vector lines stay sharp, because only scanned images are resampled, starting at 150 DPI and stepping down to 40 DPI if needed. In our tests on a 6-page scanned PDF of 5.16 MB, we measured 44 KB for the 50 KB target in 1.4 seconds, 69 KB for 100 KB in 2.1 seconds, 154 KB for 200 KB in 2.6 seconds, 284 KB for 500 KB in 7.0 seconds and 877 KB for 1 MB in 3.7 seconds. The engine is about 11 MB and downloads once, on first use. Pick the exact limit printed on your form, compress, and check the size on the result card before you upload.

Most form portals reject a PDF the moment it crosses their size limit, and a phone scan of even two pages can easily be 3–5 MB. This PDF size reducer gets your file under the limit without a laptop or an app. Choose an exact target in KB or a quality level, and the tool keeps the text crisp while it shrinks the images and scans that make the file heavy.

When do you need to reduce PDF size?

Almost every online application in India has a PDF limit, and it is usually small. Limits differ by portal — NTA's JEE Main 2027 bulletin, for example, asks for supporting PDFs of 50–300 KB — so check the exact limit printed on your form.

Common situations where a smaller PDF saves the day:

  • Uploading marksheets, caste or income certificates to a scholarship or university admission portal.
  • Attaching a resume or experience letter to a job application that rejects files over 1 MB.
  • Sending bank KYC documents or a signed form by email when the attachment keeps failing.
  • Sharing a scanned PDF on WhatsApp or uploading it over a slow Jio or Airtel 4G connection.

Why won't my PDF go below 100 KB?

Compression only removes weight from images and scans. Typed text and vector graphics are already compact, so a 40-page text-only PDF may not shrink much, while scans shrink a lot: in our tests a 6-page, 5.16 MB scan came down to 877 KB at the 1 MB target, an 83% cut.

In Target size mode the tool lowers image resolution step by step, from 150 DPI down to 40 DPI, until the file fits. Going from 300 to 100 DPI alone cuts the pixel count by about 89%. If even 40 DPI is not enough, you get the smallest size that was possible instead of an unreadable file. If your PDF is already under the target, you get the original back untouched.

  • Turn on Black & white for scans; grayscale pages are much lighter than colour.
  • Split the PDF and upload only the pages the portal actually asks for.
  • Rescan at a lower resolution if the original scan was made at 600 DPI.

Tips so the portal accepts your file

  • Zoom into the result before uploading; if stamps or small print look smudged, pick a larger target or Balanced quality.
  • Some portals count 1 KB as 1024 bytes and others as 1000 bytes, so aim a little under the limit (for example 190 KB for a 200 KB cap).
  • Remove the password from a protected PDF first; locked files cannot be compressed.
  • Keep the file name simple, without spaces or symbols, as some older portals reject them.

How does compression work without uploading your file?

The tool runs Ghostscript, a long-established PDF engine, compiled to WebAssembly so it works inside your browser. Your PDF is read and rewritten on your own phone or computer, and the result is saved straight to your device.

Nothing is sent to a server. We only record anonymous counts such as which tool was used and the file size, never the file itself or its name.

Frequently asked questions

How can I compress a PDF to 100 KB on my phone?

Open this page in Chrome or Safari, select your PDF, choose Target size and tap the 100 KB chip, then tap Compress. The work happens on your phone, so it is free, needs no app or signup, and your document is never uploaded anywhere.

Will compressing my PDF make the text blurry?

No. Typed text and vector graphics are left untouched, so they stay sharp at any setting. Only images and scanned pages are reduced in resolution. If a scanned page looks soft after compression, choose a larger target size or the Balanced quality level.

Why is my compressed PDF still bigger than the target?

Some files cannot reach very small targets without becoming unreadable, for example long documents or dense colour scans. The tool tries resolutions down to 40 DPI and then shows the smallest size it could reach. Try Black & white, or split the PDF and upload fewer pages.

Is it safe to compress Aadhaar or marksheet PDFs here?

Yes. The PDF is processed entirely inside your browser and never leaves your device. We do not store, see or upload your documents. Only an anonymous count of the tool used and the file size is recorded, with no file names or content.

Can I compress a password-protected PDF?

Not directly. A locked PDF has to be unlocked first, using the password, in a PDF reader or the app that created it. Save an unlocked copy, then open that copy here and compress it like any other file.

Why does the tool download something the first time?

The compression engine is about 11 MB and is loaded only when you use this tool, so other pages stay fast. It downloads once, after which compression runs offline-style on your device. On 4G this usually takes a few seconds.

Last updated 31 October 2026. Questions or a spec that changed? hello@documently.in