What is the regex for hex color with alpha?

The regex pattern for hex color with alpha is `^#?([A-Fa-f0-9]{8}|[A-Fa-f0-9]{6}|[A-Fa-f0-9]{4}|[A-Fa-f0-9]{3})$`. This pattern validates hex color code with optional alpha channel (3, 4, 6, or 8 digits).

How do I use this regex in JavaScript?

In JavaScript, create the regex with `const regex = /^#?([A-Fa-f0-9]{8}|[A-Fa-f0-9]{6}|[A-Fa-f0-9]{4}|[A-Fa-f0-9]{3})$/;` and test with `regex.test(yourValue)`. It returns `true` if the value matches.

How do I use this regex in Python?

In Python, use `import re; re.match(r'^#?([A-Fa-f0-9]{8}|[A-Fa-f0-9]{6}|[A-Fa-f0-9]{4}|[A-Fa-f0-9]{3})$', value)`. The raw string prefix (`r`) prevents Python from interpreting backslashes as escape characters.

Is this regex case-sensitive?

By default, yes. To make it case-insensitive, add the `i` flag in JavaScript (`/^#?([A-Fa-f0-9]{8}|[A-Fa-f0-9]{6}|[A-Fa-f0-9]{4}|[A-Fa-f0-9]{3})$/i`) or use `re.IGNORECASE` in Python.

Regex for Hex Color with Alpha

Regex Pattern

^#?([A-Fa-f0-9]{8}|[A-Fa-f0-9]{6}|[A-Fa-f0-9]{4}|[A-Fa-f0-9]{3})$

Hex color code with optional alpha channel (3, 4, 6, or 8 digits)

Quick Answer

The regex pattern for hex color with alpha is `^#?([A-Fa-f0-9]{8}|[A-Fa-f0-9]{6}|[A-Fa-f0-9]{4}|[A-Fa-f0-9]{3})$`. Hex color code with optional alpha channel (3, 4, 6, or 8 digits). This works in JavaScript, Python, Ruby, PHP, Java, and most regex engines that support PCRE syntax.

Test Examples

Input	Result
#FF5733FF	✓ Matches
#FFF	✓ Matches
#FFFF	✓ Matches
#FF5733	✓ Matches
#FFFFF	✗ No match
red	✗ No match
#GGGGG	✗ No match

Code Examples

javascript

const regex = /^#?([A-Fa-f0-9]{8}|[A-Fa-f0-9]{6}|[A-Fa-f0-9]{4}|[A-Fa-f0-9]{3})$/;
const isValid = regex.test(value);

python

import re
pattern = r'^#?([A-Fa-f0-9]{8}|[A-Fa-f0-9]{6}|[A-Fa-f0-9]{4}|[A-Fa-f0-9]{3})$'
if re.match(pattern, value):
    print("valid")

ruby

pattern = /^#?([A-Fa-f0-9]{8}|[A-Fa-f0-9]{6}|[A-Fa-f0-9]{4}|[A-Fa-f0-9]{3})$/
if value =~ pattern
  puts "valid"
end

php

if (preg_match('/^#?([A-Fa-f0-9]{8}|[A-Fa-f0-9]{6}|[A-Fa-f0-9]{4}|[A-Fa-f0-9]{3})$/', $value)) {
    echo "valid";
}

java

String pattern = "^#?([A-Fa-f0-9]{8}|[A-Fa-f0-9]{6}|[A-Fa-f0-9]{4}|[A-Fa-f0-9]{3})$";
boolean isValid = value.matches(pattern);

Frequently Asked Questions

Related Regex Patterns

Positive Integer

Integers greater than zero (no leading zeros)

Non-negative Integer

Zero or positive integer

Decimal Number

Optionally signed decimal number

Hex Color Code

3 or 6-digit hex color with optional #

USD Currency

US dollar amount with optional $ and thousands separators

RGB Color

CSS RGB color function rgb(r, g, b)