How much voltage does an American wall outlet contain?

No no, 120 volts.

Oh my bad meant to put 120 sorry

The regular outlets that most things are plugged into such as tv’s computers, refridgerators, toasters ect. are 120 volts. Other items such as an electric clothes dryer, cook stove/oven or a welder are 220 volt. 220 volt outlets are of a different configuration (not only do they look different, they are shaped different) to help prevent someone from plugging the wrong thing into it because it’s a serious saftey issue.

That’s ok !!

Average voltage for a house is 220 Volts. regular outlets are 110 volts, 60 Hertz

Currently (pun intended) the nominal wall voltage in North America is 120 V. Standard mains voltage is +/- 5% so it can range from 114-126 VAC RMS. In the past the nominal voltage was 110 and 115 VAC. Voltage regulation in the past was not as accurate either with some locales having voltages as low as 90V. 100V was ideal for Edison’s carbon fillament light bulbs so he set the standard at 110V to allow for some voltage drop in distribution; that is where we got the 110V standard but since then voltages have been creeping upward.