What the ½ symbol is
½ is a single character called VULGAR FRACTION ONE HALF (U+00BD). It packs the 1, the slash and the 2 into one compact glyph that takes about the width of one digit. You will see it in recipes (½ cup), paper sizes (8½ × 11 inches), shoe and clothing sizes, sports results and signs that say "½ price".
Because ½ is in the Latin-1 character set alongside ¼ and ¾, almost every font has it, which makes it one of the safest fraction characters to use. For thirds, eighths and the rest, see fraction symbols.
½ or 1/2?
½ is easier to read in running text and keeps mixed numbers tidy: 1½ is clearer than 1 1/2, where the space can get lost and the number misread as 11/2. Use ½ in recipes, product descriptions, social posts and anything people will read.
Use 1/2 or 0.5 when the text has to be calculated or processed. Spreadsheets treat ½ as text, not a number, so a formula that multiplies a cell containing ½ will fail. Search tools may also not match ½ with 1/2.
If you need a half that matches other built fractions, such as ³⁄₁₆, use ¹⁄₂: a superscript 1, the fraction slash ⁄ and a subscript 2.
How to type ½
On Windows, hold Alt and type 0189 on the number pad, or Alt + 171. Word also turns 1/2 into ½ automatically when the fractions option of AutoFormat As You Type is on. You can also type 00BD and press Alt + X.
A Mac has no default key, so press Control + Command + Space and search for "one half", or create a text replacement that turns 1/2 into ½ in System Settings > Keyboard. On iPhone, add the same replacement under Settings > General > Keyboard > Text Replacement. On Android, Gboard shows ½ when you long-press the 1 key on the symbols keyboard.
In HTML, use ½, and in LaTeX \frac{1}{2}.