One of the easiest and best ways to create hierarchy using size (the best way to separate things by size) is to use a constant ratio of size to bump things up.
You’ve probably heard of the “Golden Ratio,” which is supposedly all over in nature: 1 to 1.618
There’s another pretty famous option, which is 1 to 1.414 (or 1 to the square root of 2)
These numbers themselves aren’t really that important. The key here is to increase the size of your type by a constant ratio to create uniform relationships.
- Start with a small point size and a ratio
- Multiply out the point size a few times, maybe 4 times
- Pick however many of the sizes your composition needs, e.g. Header, subheader, body text would be 3
Here’s an example set of point sizes based on a base of 12 point and a ratio of 1:1.414