dhenry:
20ma is a good estimate, probably towards the upper end. 5ma is about right.If you consume materially more than that, there likely is something wrong.
@dhenry, you sound knowledgeable about electronics. Do you own a multimeter? Can you measure current?
In my page:
I actually measured (rather than guessed) the power consumption of a Uno (which this thread is about, not the raw chip). It was from 45 to 55 mA depending on the power source (9V battery or direct 5V input).
Saying 5 mA is about right is just guesswork on your part. Please don't advise people of this nonsense unless you are prepared to back it up with actual measurements, and if you do that, specify exactly what you are measuring.