You did not provide enough information.
Watts = Voltage/Amps
If you have the watts,divide it by the volts to get amps.
There are some other variables. Unless you 480 volt service in an agricultural or industrially zoned area, the lines coming out from you main circuit box are 240 volt lines approximately. They then get split into tow 115 or sometimes 120 volt lines and usually a maximum of 20 amps each branch. A device draws amperage or current, it isn't pushed into it unless there is a short circuit, which is why the current is limited at 20 amps each. How exactly this is done is technical but if the device was using 2300 watts (115 times 20 amps) it would trip the protection device. When you read a device's rating, it is often the output rating, as with a heater or motor or amplifier. You have to allow for efficiency, the more work that is done the less efficient it is, so if you operate near the 20 amp limit, you may be at say 75 percent efficiency or 1700 watts. That is why most 115 volt heaters all say 1500 watts. (volts times amps)