Twitter - how to optimise your profile image

Our little Twitter profile identity image looked great on normal screens, but on the iPhone it was sadly blurry. There doesn't seem to be any Help guidance on optimal size/resolution so it was over to trial and error.

The largest Twitter profile image size is 250 px square.

We found that an image this size saved as 72 dpi (standard screen resolution) or even 150 dpi still looked blurry on the iPhone.

What worked was an image 400 px square, and 300 dpi resolution (the normal resolution for print). See for yourself! http://twitter.com/#!/EVAlondonConf