The resolution on iOS is limited to about 16.7 million points (1 point = 1/72 inch). This means, when you multiply your page size width and height in inches, your result should be max 3,000. For example, your page size is set to 45" by 60", multiplying both values results in 2,700, which is below 3,000.
Note: Your design should also be large enough at a minimum of 1,000, for example, 8.5" by 11" is too small as both values multiplied are only 93.5. The page should be set up at a minimum of 30" by 40". Learn more about creating posters at the correct size.
How to check a PDF page size
- Open your PDF in Adobe Acrobat or in Adobe Reader
- click on File > Properties
- Your width and height should be between 30-60 inches each (multiplied no larger than 3,000).
How to change a PDF page size
Note: your version of Adobe Acrobat may be different - please refer to the Acrobat Help.
- Open your PDF in Adobe Acrobat
- Edit > Preflight > Select Prepress, Color and Transparency from the drop down on the top of the dialog
- Expand Pages in the Profiles pane
- Select Scale pages to specified size
- Click the Edit button
- In the Type of fixup window, select Scale pages
- Enter a size in inches for the short edge and for the long edge. When you multiply your width and height in inches, it cannot be larger than 3,000. If it is larger than this number, it may not display on an iPhone.
- Set the Unit to inches
- Set the Adjustment to Stretch to fill
- Click OK
- Give the file a new name that you will recognize as your resized version
Large images in your PDF
Double check any images in your PDF as well. While your PDF page size may be below the 16 million points limit, you could have an image at 6,000 x 4,000 pixels in your PDF. Multiplied together, you will have reached 24 million pixels. This is far larger than 16 million and can cause rendering issues. Ensure that you first actually resize any images to the correct pixel size smaller than 16million. Then paste or embed that resized image into your PDF.