Tertiary/caption/label/wildcard font size. Very often you will need one more font size. Sometimes it’s because your information is so hierarchical you need a tertiary style even more subdued than the secondary style. Other times, you might use uppercase for labels or buttons – and because of the increased visual weight of the uppercase, you want to use a slightly smaller size for the text itself (remember: ). So this fourth font size is a bit of a wildcard. Not every design needs it, but many do. My only warning: as much as possible, default to consistency (no strikethrough, no crazy 😛)., Body fonts should be about 16-20px. First caveat: different fonts may have the same size on paper, but appear subjectively different. Futura is much 'smaller' than Proxima Nova, even at the same specified size. Second caveat: different sites need to optimize for different things., The best practices for choosing font sizes for headings include using a consistent font size, using a larger font size for important headings, using a smaller font size for less important headings, and using a consistent line height..