What ⇕ means
Follow the convention around it. A diagram may use arrows for direction or control, while a formula may use them for logical relations. Read ⇕ by the rule or legend of its setting.
Don't confuse it with
4Questions people ask
1Why does ⇕ look different in different fonts?
Fonts draw text in different styles, so stroke weight or arrowhead shape can vary. It remains the same character.
How to type ⇕
Windows (Word)
Alt+XType 21D5, then Alt+X to get ⇕.
Windows
Win+Rrun charmap for the full table, or use the emoji picker's Ω symbols tab (Win + .).
macOS
Control+Command+SpaceOpen the character viewer and search “up down double arrow”.
Linux
Ctrl+Shift+UType 21d5, then Enter or Space.
HTML
⇕CSS
\21D5LaTeX math input
In Microsoft Word equations, `\Updownarrow` produces ⇕.
HTML
Use numeric reference `⇕` or decimal `↕`.
Codes and encoding1 code points
HTML decimal
⇕
HTML hex
⇕
CSS content
content: "\21D5";
Each escape is closed by the next backslash; a trailing space is needed before a literal hex digit.
URL encoded
%E2%87%95
1
On screen
1
Code points
1
JS .length
3
UTF-8 bytes
A visible symbol can contain several code points. JS .length counts UTF-16 units; UTF-8 counts bytes.