χ
χ Chi Symbol
Chi (χ) is the 22nd Greek letter, best known from the chi-squared test (χ²) in statistics. It is not the letter x.
Also known as: chi symbol, chi square symbol, chi squared symbol, greek chi.
Codes
| Symbol | χ | |
| Chi-squared | χ² · U+03C7 + U+00B2 | |
| Uppercase | Χ · U+03A7 | |
| Unicode | U+03C7 | |
| HTML entity (named) | χ | |
| HTML entity (decimal) | χ | |
| HTML entity (hex) | χ | |
| CSS | \03C7 | |
| LaTeX | \chi | |
| Windows Alt code | Alt + 967 |
How to type χ (Chi Symbol)
Windows03C7, Alt + X
In Word, type 03C7 then press Alt + X. Elsewhere, copy χ above or use Character Map (search “greek small letter chi”).
Mac
No default keystroke. Open Character Viewer (Control + Cmd + Space) and search “chi”, or copy χ above.
Microsoft Word03C7, Alt + X
Type 03C7, then press Alt + X to convert it to χ.
Google Docs
Insert → Special characters, then search “chi”. In an equation, \chi followed by a space also works.
LaTeX\chi
Use \chi in math mode: \chi^2 for the chi-squared statistic.
Usage
- χ² (chi-squared) is the workhorse test for categorical data — goodness of fit, and independence in a contingency table. The statistic sums (observed − expected)² / expected across cells.
- The chi-squared distribution is what a sum of squared standard normals follows, which is why it turns up wherever variances are being tested.
- Which one to use: χ (U+03C7) is the Greek letter. The Latin x (U+0078) is a different character — it will typeset with the wrong shape and spacing, and a search for the chi-squared test will not match it. In many fonts the two are nearly identical, so check the code point.
- Pronounced “kai” (rhymes with sky) in English mathematics, not “chee” — a small thing that trips people up when they first say it aloud.