RGBA to HEX converter
Convert rgba() to an 8-digit hex code with the alpha channel preserved, plus the flat hex you would get by compositing onto a background.
- Runs in your browser
- Nothing you enter is sent
- Free, no account
Three channels plus an alpha between 0 and 1.
Converted from RGBA.
Contrast on white
5.17:1
AA for body text
Contrast on black
4.06:1
AA for large text only
| Format | Value | Copy |
|---|---|---|
| HEX | #2563eb | |
| HEX with alpha | #2563ebff | |
| RGB | rgb(37, 99, 235) | |
| RGBA | rgba(37, 99, 235, 1) | |
| RGB (space syntax) | rgb(37 99 235) | |
| HSL | hsl(221.2, 83.2%, 53.3%) | |
| HSLA | hsla(221.2, 83.2%, 53.3%, 1) | |
| HSL (space syntax) | hsl(221.2 83.2% 53.3%) | |
| HSV / HSB | hsv(221.2, 84.3%, 92.2%) | |
| CMYK | cmyk(84.3%, 57.9%, 0%, 7.8%) | |
| Android ARGB | #FF2563EB | |
| SwiftUI | Color(red: 0.145, green: 0.388, blue: 0.922) | |
| Nearest CSS name | royalblue (closest match) |
CSS custom properties
--color: #2563eb; --color-rgb: 37 99 235; --color-hsl: 221.2 83.2% 53.3%;
Your colour values never leaves this tab — check it yourself—
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Why this matters
In 2025 researchers found that popular online formatters had retained tens of thousands of user-submitted snippets — JSONFormatter.org and CodeBeautify together exposed roughly 80,000 saved documents, many containing live cloud credentials, private keys and internal database connection strings, because “format this” quietly meant “upload this”. A separate incident exposed roughly 3.5 million user PDFs on a document-conversion service. The only structural fix is not sending the data in the first place: this site is served under a Content-Security-Policy whose connect-src contains no third-party origin, so a request off this device cannot be made even by accident.
Alpha as a fourth hex pair
An eight-digit hex code is #RRGGBBAA: the familiar three channels, then opacity as a
byte. The alpha conversion is multiply by 255 and round.
| Alpha (0–1) | Percent | Hex |
|---|---|---|
| 0 | 0% | 00 |
| 0.05 | 5% | 0d |
| 0.1 | 10% | 1a |
| 0.2 | 20% | 33 |
| 0.25 | 25% | 40 |
| 0.5 | 50% | 80 |
| 0.6 | 60% | 99 |
| 0.75 | 75% | bf |
| 0.9 | 90% | e6 |
| 1 | 100% | ff |
Four-digit shorthand #RGBA works the same way three-digit does, by doubling each digit
— so #f008 is #ff000088.
Alpha is an instruction, not a colour
This is the thing that trips people up. rgba(0, 0, 0, 0.5) is not a specific grey — it
is “blend black with whatever is behind me, half and half”. On white it renders as
#808080; on a dark surface it renders as near-black. That is exactly what you want for
an overlay or a shadow, and exactly what you do not want for a token that has to look identical
everywhere.
If you need one fixed colour, composite it yourself. Over a known background the maths is a linear blend per channel:
result = foreground × alpha + background × (1 - alpha)
rgba(37, 99, 235, 0.2) over #ffffff:
r = 37 × 0.2 + 255 × 0.8 = 211
g = 99 × 0.2 + 255 × 0.8 = 224
b = 235 × 0.2 + 255 × 0.8 = 251
#d3e0fb — an opaque colour that looks the same on any backgroundWhere 8-digit hex is worth using
- Design tokens. One string carries the whole value, so a token file stays a flat map of names to strings.
- Handing values to a designer. Figma accepts and displays eight-digit hex directly.
- Shadows and borders.
box-shadow: 0 1px 2px #0000000fis more compact than thergba()form and easier to scan in a list of shadows.
Where it is not worth it: anywhere a human has to reason about the opacity. rgba(0, 0, 0, 0.06)
says “6%” out loud; #0000000f does not.
Browser support
Eight-digit hex has been supported in every major browser since 2016 and there is no practical
reason to avoid it today. If you are supporting a very old embedded webview or an email client,
use rgba(), which is universally understood — the two express exactly the same colour.
Questions
How is alpha written in hex?
As a fourth pair of digits appended to the six: `#RRGGBBAA`. An alpha of 1 is `ff`, 0.5 is `80`, 0 is `00`. Four-digit shorthand `#RGBA` works the same way as three-digit shorthand does for opaque colours.
Is 8-digit hex safe to use?
Yes in every current browser. If you need to support something very old, use `rgba()`, which has been supported far longer and expresses exactly the same colour.
Why does my semi-transparent colour look different over a dark background?
Because alpha is not a colour, it is a blend instruction. `rgba(0, 0, 0, 0.5)` is grey on white and near-black on dark grey. If you need one fixed colour that looks the same everywhere, composite it against your actual background and use the resulting opaque hex.
How do I convert a percentage opacity?
Divide by 100 to get the 0–1 alpha, then multiply by 255 and convert to hex — or just type the percentage into the slider on this page and read the eight-digit value off the table.