I want to export my file from Illustrator as High Quality PDF for print with VistaPrint. So I want to export, and select High Quality PDF. But the PDF quality is 600 x 800 px and I need at least 2517 x 3544 px. How can I change that?
PDFs saved from Illustrator are always at the same size they are in your Illustrator document. Any pixel measurements you see inside Illustrator are actually just points; Illustrator assumes 1pt = 1/72 inch and for convenience assumes 1px = 1pt. But vectors have no real concept of pixels or resolution so pixel measurements inside of Illustrator should mostly be ignored unless your final output is a raster image.
Your final artwork, at 213 × 300 mm works out as 603.78 × 850.39 pt. Which Illustrator will show you as the pixel size too, but that is the correct size. That will only be the pixel size of your artwork if you export it to a 72 PPI raster image; which you aren't doing.
If you have any raster images within your Illustrator document, then they need to be at minimum that size, and you need to make sure any raster effects are rendered at the correct resolution...
So all you need to do is:
- Make sure your artboard is 213 × 300 mm
- Make sure any placed raster artwork is a minimum of 300 PPI
- Set your PDF (on the "Compression" tab of the PDF save dialog) to either not downsample images or downsample to a minimum of 300 PPI
- Set your raster effect resolution (Effect → Document Raster Effects Settings) to 300 PPI