What reaching 150 KB changes in a PDF

Set 150 KB as the target and the engine works down to it in steps, stopping at the first result that fits rather than padding the file back out.

It is the pictures inside the PDF that shrink: they are downsampled a step at a time until the file fits. Text typed into the document stays text while that is enough to reach the target. Ask for a size downsampling cannot reach and the pages are rendered to images instead, which makes the size but ends the text layer.

Files are processed on our servers, not in your browser. The upload and the result are both permanently deleted within 1 hour, no backups and no copies kept.

No watermark, and no account needed to use it. 2 files a day at up to 50 MB each, sent singly or together; signing in is free and raises each file to 100 MB.

Three things to get right before you upload

1. 1

   Copy the cap out of the form

   Whoever asked for 150 KB wrote it down somewhere: a note beside the upload button, a page of instructions, an error message. Read it again and check whether the number applies to each file or to the whole submission.

2. 2

   Give the tool the untouched file

   Hand over the version that came off the scanner. Every pass works from whatever it is given, so a file that has already been squeezed once arrives with less to work with and ends up worse at the same number.

3. 3

   Check the result, then check the size

   Those are two separate checks. Open the output and read the smallest print on the busiest page, then look at the size in your file manager to confirm it really is below the figure the form wants.

Who is actually asking you for 150 KB

Almost nothing about a PDF makes 150 KB a natural choice. A three- page scan captured at 300 DPI, weighing 13.2 MB to start with, finishes at 96 KB on its own. A file made almost entirely of photographs, 8.9 MB at the outset, finishes at 82 KB. Both sit well under this cap already. So the target matters for one reason: a form somewhere told you 150, and you need to satisfy it exactly.

Your file probably clears 150 KB without trying

The two source types people bring most often both land far below this cap. A three-page colour scan produced at 300 DPI, 13.2 MB to begin with, finishes at 96 KB. A document built out of full-page photographs, starting at 8.9 MB, finishes at 82 KB. Neither is being held back by a 150 KB ceiling.

That tells you something useful. At this target the limit is the form, not the compressor, so there is no technique to learn and nothing to adjust. Upload, ask for 150 KB, and the result will be comfortably inside it unless your document is a long bundle of scanned colour pages.

If nobody asked for 150, ask for 200 instead

When the number is yours to pick, pick 200 KB. That same photograph- heavy 8.9 MB file reaches 181 KB against a 200 KB ceiling rather than 82 KB against this one, so it keeps roughly twice as much picture information. Fifty kilobytes of extra allowance is nothing to a mailbox, a cloud drive or a messaging app.

The only good reason to stay at 150 KB is that something is enforcing it. If you are compressing to make a file easier to send rather than to get past a validator, leave this page and use the 200 KB one.

Where a 150 KB target does start to bite

Page count decides it. A one-page or three-page document has room to spare. A twenty-page scanned bundle has to divide 150 KB between twenty page images, which works out at a handful of kilobytes each, and no amount of clever encoding makes a photographed page readable on that.

Lettering and line work are safe regardless. Compression only ever reaches the pictures held inside a PDF, which is where most of the weight sits anyway. Characters typed into the document stay crisp and still selectable however small the target. It is scanned imagery, where even the words are pictures, that shows the loss.

Frequently asked questions