# amps to watts

### Help Support House Repair Talk:

#### Daryl in Nanoose

##### Well-Known Member
How do you calculate amps to watts?

#### Square Eye

##### Well-Known Member
Volts x amps = watts @ 100% efficiency.

You would need the length of the wire, the gauge of the wire and the co-efficient of the appliance you are powering to get real accuracy. The formula above is good for a ball park figure.

100 watt light bulb
120 volts

= .833 amps, in a perfect world.

#### inspectorD

##### Housebroken
Daryl in Nanoose said:
How do you calculate amps to watts?
What are you up to?

To early for christmas lights.......

#### Daryl in Nanoose

##### Well-Known Member
Thanks guys, I am figureing out how big of a inverter to get and noticed some appliances have amps and no watts. Thanks again.

##### Well-Known Member
Here is an Ohms Law chart for colculating volts and currents.
If you know 2 factors in your cicuit you can use this
chart to find the additional information you need.

Example = You want to add 3 light fixtures to your shop,
each with 1 100 watt bulb and you know you have a 115 volt
service. You would devide 300 (P) by 115 (E) to find (I) which
would be 2.06. So now you know that your new circuit needs
to be capable of handling 2.06 amps.

#### Sauna

##### Member
Easy now.. yeah no christmas light yet buddy!