1en

1en is a typographic unit used to describe a space roughly the width of the letter N in the active typeface. It is most commonly associated with the en space, a spacing unit named for this half-em width. In traditional typography, an en space is defined as half the width of an em space; therefore 1en equals 0.5em. The precise measurement of 1en depends on the font size and design, but in standard terms it scales with the font: in a 12-point font, an em is 12 points, making 1en approximately 6 points, subject to minor font metrics.

Historically, en spaces were used to achieve typographic balance in justified text and to separate certain symbols or initials. They remain part of typography in some languages and style guides, particularly for high-quality typesetting, punctuation spacing, and when preserving traditional typography in printed works. In digital typography, en spaces are supported by font metrics and can be inserted via specific character codes (U+2002 for en space).

Relation to other units is straightforward: 1em is the width of the font’s em component, so 1en is half of that. Other spacing units, such as the thin space or hair space, represent smaller fractions used for finer adjustments. In many modern workflows, flexible spacing is preferred, but en spaces still appear in typography that aims to reproduce traditional or language-specific conventions.

See also: Em, En space, Em space, En dash, Typography.