How do you calculate 8-digit hex alpha from decimal opacity?

Multiply the decimal opacity (0 to 1) by 255, round to the nearest integer, and convert to hexadecimal. For example, 0.85 * 255 = 217 -> D9.

RGBA to HEX Converter (With 8-Digit Alpha Support)

Q: Do modern web browsers support 8-digit hex codes?

Yes! CSS Color Module Level 4 introduced 8-digit hexadecimal colors (#RRGGBBAA). Supported across Chrome 62+, Firefox 49+, Safari 10+, and Edge 79+.

Q: What is the difference between CSS 8-digit HEX and Android ARGB?

CSS uses RGBA ordering where Alpha is at the end (#RRGGBBAA). Android and Flutter use ARGB where Alpha comes first (0xAARRGGBB).

How to Convert RGBA to HEX (The Mathematical Formula)

In digital color design, RGBA represents Red, Green, Blue, and Alpha (opacity). While traditional RGB uses decimal integers from 0 to 255, Alpha is typically expressed as a decimal floating-point number between 0.0 (completely transparent) and 1.0 (fully opaque).

A standard 6-digit hexadecimal color (e.g., #3B82F6) encodes only R, G, and B. To represent transparency in modern CSS and UI frameworks, an 8-digit hexadecimal color (#RRGGBBAA) adds two extra hex characters at the end to represent the Alpha channel.

The Step-by-Step Conversion Formula:

Convert Red, Green, and Blue: Divide each channel value by 16 to find the high nibble and modulo 16 for the low nibble, converting the decimal number (0–255) to a two-digit hexadecimal string (00–FF).
59 → 3B, 130 → 82, 246 → F6
Convert the Alpha Channel: Multiply the decimal alpha value (between 0 and 1) by 255, round to the nearest whole integer, and convert that integer to hexadecimal:
```
Alpha_Integer = round(Alpha_Float × 255)
Alpha_Hex = hex(Alpha_Integer)
```
For example, with an opacity of 0.85:
```
0.85 × 255 = 216.75 → 217 → Hex "D9"
```
Concatenate the 8-Digit Hex String: Combine # + Red_Hex + Green_Hex + Blue_Hex + Alpha_Hex:
#3B82F6 + D9 = #3B82F6D9

Complete 8-Digit Alpha Hex Transparency Lookup Table

Below is the authoritative reference chart for converting common opacity percentages to their exact 2-character hexadecimal suffix. You can click any row to instantly copy the corresponding hex alpha code.

Opacity %	Decimal (0.0 – 1.0)	8-Bit Value (0 – 255)	Hex Suffix (AA)	Example Code
100% (Opaque)	1.00	255	`FF`	`#3B82F6FF`
95%	0.95	242	`F2`	`#3B82F6F2`
90%	0.90	230	`E6`	`#3B82F6E6`
85% (High UI Contrast)	0.85	217	`D9`	`#3B82F6D9`
80% (Overlay / Modal)	0.80	204	`CC`	`#3B82F6CC`
75%	0.75	191	`BF`	`#3B82F6BF`
70%	0.70	179	`B3`	`#3B82F6B3`
65%	0.65	166	`A6`	`#3B82F6A6`
60%	0.60	153	`99`	`#3B82F699`
50% (Half Opacity)	0.50	128	`80`	`#3B82F680`
40%	0.40	102	`66`	`#3B82F666`
30%	0.30	77	`4D`	`#3B82F64D`
25% (Quarter Opacity)	0.25	64	`40`	`#3B82F640`
20% (Subtle Card Fill)	0.20	51	`33`	`#3B82F633`
15%	0.15	38	`26`	`#3B82F626`
10% (Glass Hairline Border)	0.10	26	`1A`	`#3B82F61A`
5% (Ultra-subtle glow)	0.05	13	`0D`	`#3B82F60D`
0% (Transparent)	0.00	0	`00`	`#3B82F600`

Frequently Asked Questions

Do modern web browsers support 8-digit hex codes?

Yes! The CSS Color Module Level 4 introduced 8-digit hexadecimal colors (#RRGGBBAA) and 4-digit hex shorthand (#RGBA). All major modern web browsers support this syntax out of the box, including Google Chrome 62+, Mozilla Firefox 49+, Apple Safari 10+, and Microsoft Edge 79+.

What is the difference between CSS 8-digit HEX and Android ARGB?

CSS uses RGBA ordering where Alpha is at the very end: #RRGGBBAA. In contrast, Android (Java/Kotlin) and Flutter use ARGB format where Alpha comes first: 0xAARRGGBB. Our converter above automatically outputs both formats so you never accidentally reverse your alpha channel when switching between Web and mobile codebases.

Why did rgba() change in modern CSS?

The CSS Working Group unified color functions. In modern CSS, rgba() is an alias of rgb(). Modern CSS allows space-separated values with a forward slash for alpha: rgb(59 130 246 / 85%). Both notations are 100% valid, and Pikka provides both snippets for copy-paste convenience.