---
title: "UTF-16 - Glossary | MDN"
chunk: 1/3
source: "https://developer.mozilla.org/en-US/docs/Glossary/UTF-16"
category: "reference"
tags: "web, html, css, javascript, documentation"
date_saved: "2026-05-05T05:47:59.541050+00:00"
instance: "kb-cron"
---

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  1. [Glossary](https://developer.mozilla.org/en-US/docs/Glossary)
  2. [UTF-16](https://developer.mozilla.org/en-US/docs/Glossary/UTF-16)

# UTF-16
UTF-16 is a [character encoding](https://developer.mozilla.org/en-US/docs/Glossary/Character_encoding) standard for [Unicode](https://developer.mozilla.org/en-US/docs/Glossary/Unicode). It encodes each Unicode [code point](https://developer.mozilla.org/en-US/docs/Glossary/Code_point) using either one or two [code units](https://developer.mozilla.org/en-US/docs/Glossary/Code_unit). Each code unit is a 16-bit value.
Code points whose values are less than 216 are encoded as a single code unit that is numerically equal to the code point's value. These code points comprise the [Basic Multilingual Plane (BMP)](https://en.wikipedia.org/wiki/Plane_\(Unicode\)#Basic_Multilingual_Plane), and include the most common characters, including Latin, Greek, Cyrillic, and many East Asian characters.
For example, the Latin character "A" is assigned the code point `U+0041` in Unicode, and this is represented in UTF-16 as the single code unit `41`.
Code points whose values are greater than 216 are encoded using a pair of code units, which is called a _surrogate pair_. The values used for surrogate pairs are not used for Unicode code points, so as to avoid ambiguity.
For example, the emoji character "🦊" (Fox Face) is assigned the code point `U+1F98A` in Unicode, and this is represented in UTF-16 as the surrogate pair `d83e dd8a`.
## In this article
  * [UTF-16 in JavaScript](https://developer.mozilla.org/en-US/docs/Glossary/UTF-16#utf-16_in_javascript)
  * [UTF-16 and UTF-8](https://developer.mozilla.org/en-US/docs/Glossary/UTF-16#utf-16_and_utf-8)
  * [UTF-16 and UCS-2](https://developer.mozilla.org/en-US/docs/Glossary/UTF-16#utf-16_and_ucs-2)
  * [See also](https://developer.mozilla.org/en-US/docs/Glossary/UTF-16#see_also)

##  [UTF-16 in JavaScript](https://developer.mozilla.org/en-US/docs/Glossary/UTF-16#utf-16_in_javascript)
Strings in JavaScript are represented using UTF-16, and many [`String`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String) APIs operate on code units, not code points. For example, [`String.length`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/length) returns `2` for a string containing a single Unicode character which is not in the BMP:
The [`String.charCodeAt()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/charCodeAt) method returns the code unit at the given index, and the [`String.codePointAt()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/codePointAt) method returns the code point at the given index:
See [UTF-16 characters, Unicode code points, and grapheme clusters](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String#utf-16_characters_unicode_code_points_and_grapheme_clusters) to learn more about working with UTF-16 strings in JavaScript.
##  [UTF-16 and UTF-8](https://developer.mozilla.org/en-US/docs/Glossary/UTF-16#utf-16_and_utf-8)
[UTF-8](https://developer.mozilla.org/en-US/docs/Glossary/UTF-8) is an alternative encoding for Unicode, which uses one to four bytes for each Unicode code point. UTF-8 is a much more common encoding for documents on the Web than UTF-16.
##  [UTF-16 and UCS-2](https://developer.mozilla.org/en-US/docs/Glossary/UTF-16#utf-16_and_ucs-2)
UCS-2 is an obsolete encoding for Unicode. It is the same as UTF-16, except it does not support surrogate pairs, so is not able to encode code points outside the BMP.
##  [See also](https://developer.mozilla.org/en-US/docs/Glossary/UTF-16#see_also)
  * [UTF-16 characters, Unicode code points, and grapheme clusters](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String#utf-16_characters_unicode_code_points_and_grapheme_clusters)
  * [UTF-8](https://developer.mozilla.org/en-US/docs/Glossary/UTF-8)
  * [UTF-16](https://en.wikipedia.org/wiki/UTF-16) on Wikipedia