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Tool #tft

RGB565 Colour Reference

A quick reference for TFT-friendly colour values, plus the conversion math so you do not have to keep re-deriving it on a napkin.

Published
#tft#arduino#colour#rgb565#reference

If you have ever bounced between a nice normal RGB colour picker and a tiny TFT library demanding 0xF81F like that is a perfectly ordinary thing to ask, welcome.

This page started life as a quick note and now lives here properly.

The format

RGB565 stores colour in 16 bits:

  • 5 bits red
  • 6 bits green
  • 5 bits blue

Green gets the extra bit because human vision is annoyingly picky and hardware people noticed.

The conversion

From 8-bit RGB values:

rgb565 = ((red & 0xF8) << 8) | ((green & 0xFC) << 3) | (blue >> 3)

Or, if you prefer to think in ranges:

  • red: 0-255 becomes 0-31
  • green: 0-255 becomes 0-63
  • blue: 0-255 becomes 0-31

A few useful values

Black   0x0000
White   0xFFFF
Red     0xF800
Green   0x07E0
Blue    0x001F
Yellow  0xFFE0
Cyan    0x07FF
Magenta 0xF81F

When this page helps

  • hard-coding UI colours for TFT displays
  • checking whether a converted value looks sane
  • saving yourself from opening the same old forum thread for the fiftieth time

If I turn this into a fully interactive converter later, this page can remain the quick-reference version for when speed matters more than bells and whistles.