Reduce PDF Size in MB

A phone scan stores each page as a colour photograph of around 2,000 pixels on its long side, a JPEG of 500KB to 1.5MB, so forty pages weigh 20MB to 60MB and every word and stamp is pixels. The first pass repacks the file and drops whatever the pages no longer refer to, which on a scan saves little: almost all the weight sits in the page images.

The second pass is where the megabytes go. Each page image is re-saved at a lower JPEG quality, the document is weighed, and if it is still over the line the images are scaled down a step and tried again. With 1,024KB shared across forty pages, each ends near 25KB: black print on white paper reads well at that weight, while a coloured letterhead or a photograph shows blocks when zoomed.

The third pass, redrawing every page as a fresh picture, runs only if the figure is still missed. On a typed document it is the pass to watch for: the characters become part of the image and can no longer be selected or searched. The card says so whenever it ran, and the redraw stops at 150 pages.

Type the figure the field states, not a rounder one beneath it, because every megabyte given away is paid for in quality. A sixty-page scan at 1MB holds about 17KB a page, at 2MB about 34KB and at 5MB about 85KB: the difference between print you can read and print you read without effort. A limit written as "less than 2MB" is a ceiling; the compressor stops a few kilobytes beneath it.

On this page a megabyte is 1,024KB, the count Windows and most server-side checks use. A phone’s file manager divides by 1,000 instead and prints 1.05MB for a file measured here as 1MB, so trust the result card rather than the file list. A few forms also count 1MB as 1,000KB; a copy of 1,020KB fails such a check, and typing 975 with the unit on KB clears both readings.

For email, stay below the cap: attachment encoding adds about a third on the wire, so a PDF of 18MB fits the 25MB cap on a personal Gmail account with room to spare.

A scanned book of 200 pages reduced to 1MB would leave 5KB a page, and no quality setting makes a page legible at that weight. Where several files are accepted, split the document into parts of forty or fifty pages and reduce each part to the limit, so every page has four or five times the budget.

Two cases do not belong here. A PDF that asks for a password before it opens is refused with a message; save a copy without the password from the reader that opens it, then come back. A file under the figure that must also clear a floor needs padding, not compression; the minimum switch below the box covers that.