With digital typography, we have the unfortunate luxury of being able to make type whatever size we want. I say “unfortunate” because for most people this is a detriment as it complicates things. Do yourself a favor, and only use these target pixel sizes: 5, 7, 9, 12, 16, 21, 28, 37, 50, 67, 83. These sizes are based off of the proportion of 3:4, and you can read more on the technical details of arriving at these sizes in How to Establish a Modular Typographic Scale.
via: lifehacker