I’ll just come out and say it: 50W. I know, I know an order of magnitude above what’s actually needed to host websites, media center and image gallery.
But it is a computer I had on-hand and which would be turned on a quarter of the day anyway. And these 50W also warm my home, although this is less efficient than the heat pump, of course.
What’s your usage? What do you host?
No idea!
Going from publicly-available info though:
Rpi4B - 6.4W max (more like 5 in real world usage)
Cpu case fan - 1.4W
2x SSD - ~6W each
13.8 to ~18 depending on what the SSDs are pulling i guess. I use it as an *arr seedbox and plex server (up to 1080p h264 works flawlessly!) as well as nextcloud