Left Right Double Arrow Symbol
The left right double arrow ⇔ indicates two-way correspondence, connection, or equivalence.
U+21D4
⇔ is a left and right double arrow symbol used to show a relationship going both ways. It’s handy in writing, diagrams, and UI text. Below you’ll find copy options and Unicode details.
Left Right Double Arrow Symbol Meaning
The symbol ⇔ is commonly used to express a two-way relationship. In logic and technical writing, it often represents “if and only if,” meaning two statements are equivalent and go together in both directions. In plain communication and design, it can suggest a mutual connection or interchangeability between two items, such as “A ⇔ B” to indicate that each corresponds to the other. It can also appear in diagrams or instructions where information flows both ways (request/response, input/output, or bidirectional mapping).
Common uses
- •Expressing “if and only if” in logic, proofs, or educational notes
- •Showing two-way equivalence or interchangeability between two terms or labels
- •Indicating bidirectional relationships in diagrams and system flow descriptions
- •Marking mutual correspondence in translation glossaries or mapping tables
- •Signaling two-way actions in UI text (e.g., sync or swap between fields)
Examples
⇔ Left Right Double Arrow (U+21D4)
- ⇔A ⇔ B (these conditions are equivalent)
- ⇔Option 1 ⇔ Option 2 (either choice matches the same meaning)
- ⇔Input ⇔ Output mapping is consistent
- ⇔Request ⇔ Response is handled in both directions
- ⇔Feature ⇔ Setting: changes apply both ways
Variations
Ready to copy
Technical codes
| Unicode | U+21D4 | |
| HTML Entity | ⇔ | |
| HTML Code | ⇔ | |
| CSS | \21D4 | |
| Alt Code | Alt + 8660 | |
| Decimal | 8660 |
How to type Left Right Double Arrow Symbol (⇔)
On Windows
Hold Alt and type 8660 on the numeric keypad. In Word, type 21D4 then press Alt + X.
On Mac
Switch to the Unicode Hex Input keyboard, then hold Option and type 21D4. Or press Control + Command + Space and search.
On Linux
Press Control + Shift + U, type 21d4, then press Enter or Space.
Anywhere
Copy ⇔ with the button above and paste it wherever you need it — this works on every device and in every app, with no keyboard shortcut to remember.
FAQ
What does ⇔ mean?
⇔ commonly means a two-way relationship, often equivalence (“if and only if”) in logic, and mutual correspondence in general writing.
How do I type or enter ⇔ in HTML?
Use the HTML entity: ⇔ (or ⇔).
What is the Unicode for ⇔?
The Unicode code point is U+21D4, named LEFT RIGHT DOUBLE ARROW.
Is there a different name for this symbol?
Yes—it's also commonly called the Left Right Double Arrow (Unicode name: LEFT RIGHT DOUBLE ARROW).