How to compress a PDF (and reduce its file size)

Text barely affects a PDF's size: a 100-page report of plain text is often under 1 MB. What makes PDFs big is images. A phone scan stores every page as a photo, and slides or brochures contain high-resolution pictures that are far sharper than any screen needs.

Fonts and hidden extras add a little too: embedded fonts, thumbnails, metadata and leftover editing data. Compression tools mostly win by re-encoding images at a sensible resolution and quality.

1. 1Open Compress PDF and choose your file. You can add several PDFs at once.
2. 2Pick a level. Less keeps images closest to the original, Recommended is the best balance for most files, and Extreme gives the smallest file with softer images.
3. 3Optionally turn on Grayscale images (good for black-and-white documents) and Remove metadata.
4. 4Press Compress PDF. The result shows the old and new size; download the file.

The compression runs in your browser, so the PDF is never uploaded. That matters for statements, IDs and contracts.

• Recommended: email attachments, upload portals and sharing. Photos still look clear on screen and print acceptably.
• Extreme: when you must reach a small limit, and the document is mostly text or a black-and-white scan.
• Less: brochures, portfolios and anything with photos you care about.

If a file is mostly text and barely shrinks, that's expected: there are no large images to reduce. It is probably already as small as it will get.

Some portals cap each file at 2 MB or 5 MB, and a long scan may not fit even after compression. In that case split it: Split by size makes as many parts as needed, each under the limit you set, in the original page order.

For GST replies and appeals, GST filing prep does both steps in one go for the 2, 5 and 10 MB limits. If the PDF started life as photos, it can also help to compress the images before putting them into a PDF.