Multiplication Sign (×) vs. Letter x
The multiplication sign “×” and the letter “x” can resemble each other but are not the same character. Unicode identifies × separately, and the SI Brochure uses the multiplication sign in scientific notation. Dimensions, variables, and plain-text contexts can follow different conventions, so context still controls.
Use “×” as the multiplication sign in mathematical or technical notation when the standard calls for it; use “x” when you mean the letter or variable x.
Key details
Important caveats
Usage Boundary
Use x when it is a letter or variable; use × for multiplication when the relevant mathematical, technical, or editorial convention requires it.
Further guidance
Character Identity
Unicode identifies × as U+00D7 MULTIPLICATION SIGN, distinct from the Latin letter x.
Practical Application
Use the mathematical multiplication sign “×” when the notation requires multiplication; use the letter “x” only when it is genuinely a variable, letter, or context-specific symbol. Preserve established dimension conventions where the governing style intentionally uses a different separator.
Reader Check
If you replace the character with the word “times,” does the mathematical meaning stay the same, or is the character actually the variable/letter x?
Technical Use
The SI Brochure uses the multiplication sign in scientific expressions such as a coefficient multiplied by a power of ten.
Worked Example
Write “3 × 4 = 12” for multiplication. In “solve for x,” the character is the letter x and must not be replaced with the multiplication sign.
Sources and evidence
Sources are shown with the role they play in this guide. Historical or style-sensitive claims are kept within the evidence boundary described above.
- Latin-1 Supplement — Unicode Names List (opens in a new tab)Unicode Consortium · Unicode character identities for degree sign, plus-minus sign, and multiplication sign
- The International System of Units (SI), 9th edition, version 4.01 (opens in a new tab)Bureau International des Poids et Mesures · SI conventions for unit symbols, Celsius temperature spacing, angle-degree notation, and multiplication notation