This exposes the hidden structure.
These tools expose the structure behind something that usually gets judged by eye: line length, hierarchy, wrapping, spacing or fit.
Type, Layout & Effects
Compare these fonts.
See the same copy in two font families at the same size.
Fonts
Side-by-side comparison
The quick brown fox jumps over the lazy dog. 0123456789
The quick brown fox jumps over the lazy dog. 0123456789
Type any installed font family name into the fields.
Useful to know
Four things worth knowing.
Neat maths can still look wrong.
The mathematically neat answer can still look wrong. Typography and layout have an optical component that a counter cannot see.
Check it where people see it.
Judge it at the size it will actually be used. Typography and spacing are partly optical.
Optical judgement still matters.
Judge the result at its final size. A headline that works in a desktop editor can fall apart on a phone or projected slide.