How to use it
- Enter a colour. Paste a hex, rgb() or rgba() value, or use the picker and alpha slider.
- Say which 8-digit order you mean. Choose CSS (#RRGGBBAA) or Android (#AARRGGBB) for 8-digit input.
- Copy the format you need. Copy the XML, Compose, Kotlin, Java or Flutter value.
Why the alpha moves
A hex colour with transparency has eight digits, and the two worlds disagree on where the alpha goes:
| Platform | Order | 80% opaque blue |
|---|---|---|
| CSS / web | #RRGGBBAA | #3B5BFDCC |
| Android XML | #AARRGGBB | #CC3B5BFD |
| Compose / Flutter | 0xAARRGGBB | Color(0xCC3B5BFD) |
Pasting #3B5BFDCC into an Android colour resource reads "3B" as the alpha (23% opaque) and shifts every channel — a classic cause of washed-out status bars and splash screens.
Kotlin and Java ints
In Kotlin, 0xCC3B5BFD is larger than Int.MAX_VALUE and is typed as Long, so the tool adds .toInt() when alpha is above 127. In Java the same literal is a valid negative int.
Choosing your app's theme colour for APK Maker? The CSS hex value is what the builder expects. See converting HTML to APK.
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Frequently asked questions
What is #AARRGGBB?
Android's 8-digit hex colour format: two digits of alpha (opacity) followed by red, green and blue.
How do I write a transparent colour in Android XML?
Put the alpha first: 50% black is #80000000.
Is Flutter's Color the same as Android's?
Yes for the hex literal: Flutter's Color(0xAARRGGBB) uses the same alpha-first order.