I'm designing for a screen that has the following specifications:

  • 4.3” Diagonal

  • Screen Size 272 x 480 dots

  • Pixel Size 0.198 x 0x.198 mm

  • Actual Area 95.040 x 53.856 mm

  • 53.856 mm = 2.12 inches

  • 95.040 mm = 3.74 inches

  • 272 / 2.12 = 128 pixels / inch horizontal

  • 480 / 3.74 = 128 pixels / inch vertical

I have, say, an icon in Illustrator. It is 13px x 20 px (the Artboard is 272 x 480). When I export it at 72 dpi, it comes in at the right size, but this is half the pixel density that the screen is capable of. When I try to export it at 128 dpi, it becomes larger.

Note: I do not have 'use artboards' checked, because I want to just export this one icon.

This doesn't quite make sense to me, Is there a way that I can constrain the size in physical units (mm, in) and still have the resolution that I need?

Thank you for your help!

  • 1
    When the icon is "the right size", does it appear pixelated compared to other graphics on the screen? Or do you want 128 ppi because it is mentioned in the specifications? I can't be sure, but my guess is that the icon is fine as it is. 72 ppi is just the old standard resolution setting for screens. In reality most applications (web browsers for example) disregard the resolution setting and just displays the pixels 1:1. If you do have a problem with pixelation it might be an implementation problem.
    – Wolff
    Jul 5 '18 at 20:22
  • 2
    Possible duplicate of How to resize design 4500*5400 px in Illustrator CS6?
    – LeoNas
    Oct 4 '18 at 20:13
  • All that matters is the number of pixels. PPI is not relevant for images intended to be displayed on-screen.
    – Billy Kerr
    Apr 26 '20 at 17:47

Most systems ignore PPI settings, it is basically only usful for print*. But its so ingrained in adobes workflow that they cant drop it. Basically 72 PPI is the closest thing to "no resolution" as adobe can manage.

Now in fact it makes very little sense to have a unit size for pixels. Because pixels can have arbirary sizes, and differnet parts of your arwork may in fact have different densities. But its been added there for the simple purpose that some users want to think in pixels. Theres basically 2 ways of doing this:

  • Make fixed size, so they use the NOT set size.
  • Make a flexible size, but ultimately this is VERY confusing for your average Adobe user (who really does not even understand what PPI is, just like you).

So either design in pixels or units. Then dont use save for web but just save it allows you to plug in a value directly.

Note the PPI value does not matter. There is no such thing as pixel densiy on the digfital image not indemnded for print. All teh digital system cares about is pixels. The PPI value has no significance for the image output!

* So only useful for ouptuts that are not digital. So does not matter one pixel is one pixel, PPI has on effect that or even the quality of the pixel.

In fact PNG does not even have a PPI field, it is just in the Adobe extension. PNG does have a physical resolution field that can't be set to exactly 72 PPI, which not many programs support it. And adobe will ignore it and use its own extension... Be very careful with PPI and PNG because of this.

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