A limit most documents can meet
One megabyte leaves space for a good deal of picture. Reports with a few photos, presentations, and scans of a page or two usually fit at Balanced, because the pictures are brought down to 150 dpi, which is what a screen or an ordinary printer can use. The big reductions come from pictures that are far larger than they are shown, and from pages that were saved without compression.
Four of our five test PDFs fitted at Balanced with room to spare. The fifth, six pages of full page photos at 4.8 MB, needed its pictures at about 127 dpi to reach 983 KB. That is about 1,050 pixels across an A4 page, still comfortable to read on a screen. The tool gets there by trying a resolution, measuring the file, and adjusting, so the result is close under 1 MB and not far below it.
Email and one megabyte
An attachment grows by about a third when it is sent by email, because attachments are encoded as text. A 1 MB PDF arrives as about 1.3 MB. That is fine for any ordinary limit, but remember it when a service says 1 MB for the whole message. If several PDFs must go together, compress each, and keep the total in mind.
For a limit that is much lower, see the pages for 500 KB, 200 KB and 100 KB, or a more relaxed 2 MB.
What the limit does to each kind of PDF
- Slides and reports with oversized pictures: no extra reduction. Our deck went from 38 MB to 80 KB at Balanced.
- Scans: usually none either. In our test a colour A4 scan came to 234 KB at Balanced, so a PDF of five or more different scanned pages starts to need a lower resolution at 1 MB.
- Photo pages: the picture resolution is lowered just enough. Without a limit the same file was 2.0 MB.
- Text: no change in the text at any limit. Only how the file is stored can shrink.