Compress PDF to 300 KB — merge and shrink without uploading

How to use Compress PDF to 300 KB

1. If you have several separate scans, combine them into one PDF first with the PDF Merger, in the order the form expects.
2. Open the combined PDF here. The target reads 300 KB.
3. Leave If needed, convert pages to images to reach the size on, and tick Black and white only if every page is plain text.
4. Click Compress to 300 KB.
5. Scroll through the preview page by page, then download the file ending in -300kb.pdf.

What it does and when to use it

Some application forms give you one upload slot for several documents. A visa or admission portal might ask for proof of address, a bank letter and an ID in a single PDF under 300 KB; a scholarship form might want all supporting certificates together. The limit is generous for one page but tight once four or five scans are joined.

This tool compresses the combined file so it fits, choosing the highest quality that stays under 300 KB. Pages that were typed and exported to PDF, rather than scanned, are cheap in bytes; scanned pages and photos are where the budget goes.

Building a bundle that fits

A little preparation makes a large difference at this size.

1. Collect only what is asked for. Every extra page takes bytes away from the others.
2. Fix orientation. Turn sideways pages upright with the PDF Rotator so the final document is easy to review.
3. Put pages in order. The PDF Reorder tool lets you drag pages into place after merging.
4. Remove blank backs. Duplex scanners often add empty pages. Delete PDF Pages removes them.
5. Then compress once. The tool divides the 300 KB across the pages that remain.

How it works

All processing takes place in your browser tab. pdf-lib and a WebAssembly build of qpdf handle the lossless repacking, and pdf.js renders pages when conversion to images is needed.

The tool returns your file untouched if it is already under 300,000 bytes. If not, it tries the lossless rebuild and keeps it if that fits. Otherwise it renders all pages, saves them as JPEG images in a new PDF, and searches for the best combination of quality and resolution. It begins at 150 DPI with quality between 35% and 85%, then steps the resolution down only when needed. Every page in the bundle uses the same settings, so the document looks consistent from start to finish.

Worked examples

Four one-page scans merged into one PDF. Together they might be a few megabytes, depending on how they were scanned. Once compressed to 300 KB, each page has about 75,000 bytes, which is usually plenty for clear text at a moderate resolution. The result panel shows the DPI and quality used.

Six pages, two of them photos. The photos pull the shared quality down for every page. If the text pages look soft, try a cleaner scan of the photo pages, or check whether the form accepts the photos separately.

A bank letter saved as a PDF from online banking. These are usually small already. If the bundle is mostly digital documents like this, the lossless pass may bring it under 300 KB without converting anything to images.

Limits and tips

• Converting to images removes selectable text and links from every page, not only the scanned ones. Keep your originals.
• If the target is out of reach, the tool tells you the smallest size it achieved. Dropping one page or switching to black and white is usually enough.
• Tighter limit? Compress PDF to 200 KB. More room available? Compress PDF to 500 KB.