I often hear people talking about the proper dpi/ppi to use when creating images for websites. Here is the simple answer: it doesn’t matter at all. Not even a little bit.
It is certainly a big deal when designing print pieces, as that’ll make a big difference in how it looks. On the web, though, all that matters is pixels. It’s often said that web images should be 72 ppi, but that doesn’t matter. 72 ppi is fine, but certainly not required.
As an example, here are four images that are each 300×300 pixels in size, but with varying levels of ppi:
72 ppi, 19.7KB |
300 ppi, 19.7KB |
1 ppi, 19.7KB |
10,000 ppi, 19.7KB |
On the web, it clearly doesn’t matter. However, you’ll want to keep those high-resolution (and high ppi) files for printing in a separate location. If I ever scale an image down for the web, I make sure to keep an original high-resolution copy of the image safe somewhere.
Another consideration are the new HD/Retina displays coming out, that show images in a sharper resolution than they’re shown on the screen. This still has nothing to do with ppi. As explained by mobify:
So if you want to create an HD image at 200 x 200 on a Retina display, create the image at 400 x 400 then use CSS to control the HD image down to 200 x 200: img { width:200px; height:200px; }.
So there you go. Use any ppi you want, just make sure your images are sized correctly!
Although not strictly ‘the web’, mobile app/web developers require a good appreciation of pixel-density, and work with density-independent pixels (dp’s). I’m sure this has led, at least in part, to a resurgence in discussions about “dpi & ppi”. See http://developer.android.com/guide/practices/screens_support.html
Good info, thanks!
Thanks for the info and ‘lingo’ explanation. I usually get all those confused.
It’s true. Web is based entirely on set measurements, so your pixel ratio doesn’t matter at all. If you are looking for higher quality, then you need to be looking at the image type, the saving quality settings, and the quality of the original image.