You forgot 8bit to 10bit encoding, plus a little extra res for H blank and V blank. (check the HDMI spec), and you don't need to add for audio, that's encoded into the H & V blank.
The figures are:
(Horizontal Res + Horizontal Blank) * (Vertical Res + Vertical Blank) * Frequency * Bit Depth * Channels
Or
(1920+280) * (1080+45) * 60 * 10 * 3 =
4.455 Gbps
(Check the quoted bandwidth for most
HDMI cables to see 4.95Gbps quoted everywhere too, guaranteed to have just enough B/W for a 1080P@60Hz signal, It's known as the "Guaranteed Standard Speed").
Which is exactly the figure quoted by the HDMI Org for a 1080P@60Hz signal over HDMI.