I'm working on some site banners that need updating and I'm having a few issues with dimensions.

My internet screen is set to 'view actual size', so it's not zoomed in and my images/slices are always saved at 72ppi (not that it matters much for online?).

When i screen grab one of the existing banners from the website, with a view to keep the size the same and simply refresh the image to send to the developers, I'll drag the screen grab into photoshop and draw a slice around it. The dimensions of the slice are 1553px x 330px.

However, the developers have asked for the dimensions to be 786px x 164px, and have apparently had to resize all my previously supplied banners which were 1553 x 330.

Any ideas on why the two dimensions would be so different? I can't understand how they can have such a gap in size.

Any ideas/suggestions would be very much appreciated!!

  • Do you have a retina display?
    – Scott
    Oct 3, 2013 at 11:49

2 Answers 2


It sounds like you're taking these screenshots from a MacBook with Retina Display.

I struggled with this for a while myself, but I found this great free app called RetinaCapture (http://www.retinacapture.com/) that lets you work around the problem without having to fiddle with the CLI.



Do not rely on dpi for measurements: you want to work with exact pixel dimensions always. If you screen grab something, set your pixel dimensions directly.

If you re using a device such as a Mac with Retina, it is possible that the mac is "pretending" to be one pixel resolution (such as 1920x1080) but actually rendering at a higher resolution. In this case "actual size" is not what you think it is, because the software is scaling things "behind your back."

  • 1
    It is indeed likely to be Apple's retina display. A screenshot from a retina display would produce 1572x328 pixel image if you grab 786x164 (all dimensions are doubled). The difference to the mentioned 1553x330 may be caused by inaccurate slicing in Photoshop. @abi But why not just save banner images instead of making a screenshot?
    – Slava
    Oct 3, 2013 at 16:58
  • to clarify, if you screen shot on a retina, you'll have twice the pixels in each dimension than if you screen shotted on a non-retina device. For example: a 100px x 100px image, when screen shot on a retina display, would be 200px x 200px.
    – DA01
    Oct 3, 2013 at 17:27
  • Screenshots are not the best way to go, but another quick solution/workaround for screenshotting is if you scale down the zoom in your browser by 50%. In Chrome for example, ctrl with + or - zooms in or out. Zoom to 50% and grab half the area...
    – John
    Feb 11, 2014 at 23:54

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