The biggest electric heaters which you can buy off the shelf will be 1500 Watts and will all provide the same amount of heat. Some will have a built in fan and oscillate to help circulate the air. The maximum is capped at 1500 Watts since this is the largest the UL will approve for a 15 amp circuit.

It typically does not take much energy to heat a basement. I would think one 1500 Watt electric heater would be enough to heat an area of 300 sq. feet. See how one works before spending the money on a second.

If you are going to have two units they will need to be plugged into two separate 15 amp circuits. The portable electric units are the cheapest solution. Installing baseboard heaters would be convenient but will cost a lot more money.

Thanks so much for your help.

We'll try with running one heater until we can figure out how many circuits are in the basement.

Thanks again.