How many bits are used by standard RGB truecolor with 8 bits per channel? The answer is 24 bits.
RGB truecolor stores three colour channels: red, green and blue. With 8 bits assigned to each channel, the total is 8 + 8 + 8, or 24 bits per pixel. Each channel can represent 256 intensity levels, from 0 through 255.
Combining those channels produces 256 × 256 × 256, or 16,777,216 possible colour combinations. That huge palette is why 24-bit colour is commonly called truecolor or “millions of colours.” It became a standard approach for computer displays and image formats.
A frequent mix-up is 32-bit colour. In many systems, the extra 8 bits are not a fourth colour channel; they store an alpha value for transparency or remain unused. By contrast, 48-bit colour generally means 16 bits for each of the three RGB channels, giving greater precision rather than simply more primary colours.