Compress PDF files

Runs on your device — nothing is uploaded

Bring a PDF under an upload limit without sending it to anyone. Three levels let you choose between keeping text selectable and squeezing out the smallest possible file.

How it works

1. Add the PDFDrop the oversized document onto the box.
2. Pick a levelLight keeps text selectable. Recommended tries both approaches and keeps whichever is smaller. Strong gives the smallest file but turns each page into an image.
3. DownloadYou are told exactly how much smaller the file got. If it could not be shrunk, you receive the original unchanged rather than a bigger file.

Which compression level to choose

Start with Recommended. It re-saves the file with tighter internal structure first and only falls back to re-rendering the pages if that barely helped, so you usually keep selectable text and still get the size down.

Use Light when the document is mostly text — a contract, a report, an invoice — and you need the words to stay searchable and selectable afterwards. Light is lossless: nothing about the pages changes, only how the file stores them internally.

Use Strong when you are fighting a hard limit and the document only has to be legible. Each page is rendered to an image at 110 dpi and re-embedded as a JPEG, which can cut a scan to a fraction of its original size. The trade-off is real: text stops being selectable, searchable or copyable, and fine print may soften. Never use Strong on a document that someone has to read on screen at low zoom, and never on a file that must remain accessible to a screen reader.

Why a PDF is large in the first place

Almost always images. A single A4 page scanned at 600 dpi as an uncompressed bitmap is around 50 MB on its own; the same page at 300 dpi as a JPEG is a few hundred kilobytes. Text, by contrast, is tiny — the entire text of a 300-page novel is well under a megabyte.

That is why scanned documents shrink so dramatically and text documents barely move. If your PDF is mostly words and the compressor only shaved a few percent off, the file was already efficient and there is very little left to remove.

Hitting a specific upload limit

If a portal enforces a limit such as 100 KB, 500 KB or 2 MB, start with Strong and check the reported result. If it is still too big, the cause is almost always image resolution that is far higher than the document needs. Converting the pages to images at a lower resolution is the reliable lever — for a text-only document, going below roughly 100 dpi starts to make the letters ragged.

Remember that a PDF can also be split. Two files of 900 KB both fit under a 1 MB limit where one 1.8 MB file does not.

Questions

Which level should I choose?

Start with Recommended. Use Light when the document is mostly text and you need it selectable, and Strong when you are fighting a hard size limit and can accept pages as images.

Why did my file barely change?

Scanned and image-heavy documents compress well; PDFs that are already optimised, or that contain modern compressed streams, have almost nothing left to remove. The tool tells you honestly when that happens.

Does compressing reduce quality?

Light and Recommended keep the original page content intact. Strong re-renders each page, which reduces image sharpness and makes text non-selectable.

Is there a file size limit?

No artificial limit. Very large files depend on your device memory — around 150 MB is a sensible ceiling for most browsers.

Will compression remove my bookmarks or links?

No. Structural re-saving preserves bookmarks, links and annotations. The Strong level replaces page content with images, so any links drawn on the page stop being clickable, but the document structure survives.

What is the smallest a PDF can get?

For a text-only document, usually not much below what Light achieves — the content itself is already small. For scans, the floor is the size of the images you are willing to accept, which is why Strong can often get a scan below 10% of the original.

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