Level: Basic
Text that's too small forces visitors to strain or zoom, quietly undermining the entire experience regardless of how good the rest of the design looks.
16 Pixels Is a Common, Reasonable Body Text Baseline
While not a universal rule, a body text size around this range tends to balance readability with efficient use of space across most devices.
Headings Should Create Clear Size Contrast
A heading only slightly larger than body text fails to create the visual hierarchy headings are meant to provide.
Never Rely Solely on Visual Testing at One Screen Size
A font size that looks fine on a large desktop monitor can feel too small once viewed on an actual mobile device.
Next step: Use the Webpage Screen Resolution Simulator to check how your current font sizes actually render across a range of real device screen sizes.