typography
Leading
also called line height (css), line spacing
The vertical distance from one baseline of type to the next, which sets how a paragraph holds together as a block.
Designers say leading, developers say line-height, and they are talking about nearly the same thing. The word is metal-type history: strips of lead placed between lines to space them out, which is why it rhymes with “bedding” and not with “reading”.
Nearly the same, because the two are measured differently. Leading is baseline to
baseline; CSS line-height distributes its space above and below the text box, so
half of it lands over the first line and half under the last. A unitless value like
1.5 is the safe form, since it scales with each element’s own font size instead
of being inherited as a fixed pixel amount.
Body text usually wants somewhere between 1.4 and 1.6. Long measures need more, since the eye has further to travel back to find the start of the next line; large headlines need less, often below 1.2, because the same ratio at 48px opens gaps that break the phrase apart. Both of this term’s neighbours are horizontal: tracking spaces every letter in a run, kerning fixes one troublesome pair.
Which word?
| If you want | say |
|---|---|
| the vertical space between lines of type | leading |
| space added to every letter across a run | tracking |
| the space between two particular letters | kerning |
| deciding what sizes are allowed to exist at all | type scale |
| deciding how wide a paragraph is allowed to get | measure |
| proving a layout survives reader-set spacing | text spacing |
| spacing paragraphs and headings by one consistent unit | vertical rhythm |
| explaining the mystery padding around a line of text | half-leading |