🎨 RGBA to HEX Converter

What is the RGBA to HEX Converter?

An RGBA color describes a pixel with four numbers: how much red, green and blue light it emits (each 0 to 255) and an alpha value that says how opaque it is. Alpha runs from 0 to 1 in CSS, where 0 means you see straight through to whatever is behind, and 1 means the color is solid. The familiar 6-digit hex code (#RRGGBB) can only store the three color channels, so for years there was no way to write transparency directly in a hex string.

The 8-digit hex notation, often called hex8, fixes that by adding a fourth pair of hex digits for alpha: #RRGGBBAA. Each pair is a single byte written in base 16, from 00 to FF (0 to 255 in decimal). The conversion is the same for every channel: take the 0 to 255 value, divide by 16 to get the first hex digit and use the remainder for the second. Alpha is the only channel that needs an extra step, because CSS alpha is a 0 to 1 fraction. You scale it to a byte first by multiplying by 255 and rounding, so 0.5 becomes 128, which is 80 in hex.

Because alpha is squeezed into 256 steps, the round trip is not always perfectly exact. An alpha of 0.5 stored as 80 hex reads back as 128 over 255, which is 0.5019..., usually rounded to 0.50 for display. This is harmless for screen colors but worth knowing if you compare a hex8 value against the original fraction. Modern browsers support #RRGGBBAA in CSS, so you can drop the converted code straight into a stylesheet without writing a separate rgba() rule.

When to use it

• Saving a semi-transparent CSS color as a single 8-digit hex token in a design system or theme file.
• Converting an rgba() value from a design tool into the #RRGGBBAA syntax some frameworks and configs expect.
• Reading an unfamiliar 8-digit hex back into rgb and an alpha you can reason about.
• Pulling the alpha out of a color as its own AA hex byte to reuse on other shades.

How to use the RGBA to HEX Converter

1. Enter the red, green and blue channels (each 0 to 255) and the alpha (0 to 1).
2. Read the 8-digit hex (#RRGGBBAA), the 6-digit hex, and the alpha byte as hex.
3. To go the other way, type or paste an 8-digit (or 6-digit) hex into the hex field.
4. Check the swatch over the checkerboard to judge the transparency, then copy the #RRGGBBAA code.

Formula & method

Worked examples

Common CSS alpha values and their hex (AA) byte

Common mistakes to avoid

• Writing the alpha pair before the color, not after. The CSS standard order is #RRGGBBAA, with alpha last. Some other systems use #AARRGGBB (alpha first), so a value that looks right can render with the wrong opacity if you mix the two conventions.
• Treating alpha like a 0 to 255 channel. CSS alpha is a 0 to 1 fraction, not a 0 to 255 byte. You must multiply by 255 before converting to hex. Putting 0.5 straight into a hex pair gives nonsense.
• Expecting an exact round trip. Alpha only has 256 possible hex steps, so 0.5 stores as 80 and reads back as 0.5019..., which displays as 0.50. Small fractions can drift by a hair after a round trip.
• Assuming every browser reads 8-digit hex. Hex8 is well supported in current browsers, but very old ones ignore it. If you must support legacy targets, keep an rgba() fallback alongside the #RRGGBBAA value.

Glossary

RGBA

A color model with red, green and blue channels (0 to 255 each) plus an alpha channel for opacity (0 to 1).

Alpha

The opacity of a color, from 0 (fully transparent) to 1 (fully opaque). It does not change the color itself, only how much shows through.

Hex8 (#RRGGBBAA)

An 8-digit hexadecimal color code where the last two digits encode the alpha as a byte from 00 to FF.

Byte

A value from 0 to 255, written as two hexadecimal digits (00 to FF). Each color channel and the alpha use one byte.

Hexadecimal

A base-16 number system using digits 0 to 9 and letters A to F, the standard way to write color values on the web.

Frequently asked questions