What fits in half a megabyte
Half a megabyte holds a document of text with several logos and charts, or a few pages of well compressed scans. Our test PDF of six pages, each one large photo, came to 2.0 MB at Balanced, with its pictures at 150 dpi. The 500 KB limit took the pictures down to about 101 dpi, which is 835 pixels across an A4 page, and the file to 460 KB. Pages that are all picture shrink the most, and they also lose the most detail.
Text-heavy documents with a few pictures usually fit at Balanced already. The tool then returns that result, instead of squeezing the pictures further than needed. Four of our five test PDFs did exactly that.
What a resolution looks like on a page
Resolution is counted in pixels per inch (dpi) at the size a picture is printed on the page. For a full width picture on an A4 page, these are the sizes you get:
- 150 dpi: 1,240 pixels across. Sharp on screens, and fine for printing text documents with pictures.
- 100 dpi: 827 pixels across. Clear on a screen at page size, soft when you zoom in.
- 72 dpi: 595 pixels across. Readable, but plainly low resolution.
- 56 dpi: 463 pixels across. The lowest the tool goes.
In our tests a 500 KB limit left the photo PDF at about 101 dpi, and the PDFs with scans, screenshots and slides at 150 dpi because they already fitted.
If it does not fit
- Look at which pages are heavy, and consider whether they all need to be in the file.
- Choose black and white or grey when you scan, which keeps the file small before it reaches this tool.
- Try again from the original file rather than from one that was compressed before.
Merge PDF and Split PDF help you reorganise the pages, and then you can compress the final file.