Html Entity Encoder Calculator
Use our free Html entity encoder tool to get instant, accurate results. Powered by proven algorithms with clear explanations.
Reviewed by Daniel Agrici, Founder & Lead Developer
Formula
Special characters are replaced with &entity; references
HTML entities replace characters that have special meaning in HTML (like <, >, &, quotes) with escape sequences that browsers display as the literal character instead of interpreting as HTML syntax. This prevents parsing errors and XSS security vulnerabilities.
Worked Examples
Example 1: Encoding HTML Tags for Display
Problem:Encode the string '<h1>Hello & \"World\"</h1>' for safe display in HTML.
Solution:Character-by-character encoding:\n< becomes <\nh, 1 remain unchanged\n> becomes >\nH, e, l, l, o, space remain unchanged\n& becomes &\nspace remains unchanged\n\" becomes "\nW, o, r, l, d remain unchanged\n\" becomes "\n< becomes <\n/, h, 1 remain unchanged\n> becomes >
Result:<h1>Hello & "World"</h1>
Example 2: Decoding HTML Entities to Text
Problem:Decode the string '<p>Price: $5 & © 2024</p>' back to readable text.
Solution:< decodes to <\n> decodes to >\n& decodes to &\n© decodes to the copyright symbol\nOther characters remain unchanged.
Result:<p>Price: $5 & (copyright) 2024</p>
Frequently Asked Questions
What are HTML entities and why do we need them?
HTML entities are special text sequences that represent characters which have special meaning in HTML or are not easily typed on a keyboard. They start with an ampersand (&) and end with a semicolon (;). HTML entities are necessary because certain characters like <, >, &, and quotation marks are part of HTML syntax. If you write <div> in your content, the browser interprets it as an HTML tag rather than displaying the text. By encoding it as <div>, the browser displays the literal text. HTML entities also enable displaying characters from other languages, mathematical symbols, and special typography that might not be available on your keyboard.
What is the difference between named, numeric, and hex HTML entities?
HTML entities come in three formats. Named entities use descriptive words, like & for ampersand and © for copyright symbol. They are easy to read but only exist for commonly used characters. Numeric (decimal) entities use the character's Unicode code point in decimal, like & for ampersand. They work for any Unicode character. Hexadecimal entities use the hex code point, like & for ampersand. Numeric and hex entities are functionally identical and cover all Unicode characters. Named entities are preferred when available because they are more readable in source code, but numeric entities are the universal fallback for characters without named equivalents.
Which characters must be encoded in HTML?
Five characters have mandatory encoding requirements in HTML. The ampersand (&) must be encoded as & because it starts entity references. Less-than (<) must be < because it starts HTML tags. Greater-than (>) should be > for symmetry and to prevent parsing issues. Double quotes (\") must be " inside attribute values. Single quotes (or apostrophes) should be ' inside single-quoted attributes. Beyond these mandatory characters, encoding is recommended for non-ASCII characters, invisible characters like non-breaking spaces, and characters that might be misinterpreted by different character encodings. Proper encoding prevents display errors and security vulnerabilities.
How does HTML entity encoding prevent XSS attacks?
Cross-Site Scripting (XSS) attacks inject malicious scripts into web pages by exploiting unencoded user input. If a user enters a script tag containing JavaScript and the application displays it without encoding, the browser executes the malicious script. HTML entity encoding neutralizes this threat by converting < to < and > to >, which the browser displays as text instead of interpreting as HTML. For example, a script tag becomes visible text rather than executable code. This is why server-side output encoding is a fundamental web security practice. All user-generated content should be HTML-encoded before insertion into the page to prevent script injection attacks.
References
Reviewed by Daniel Agrici, Founder & Lead Developer · Editorial policy