Does a 115 volt 1500 watt toaster oven use as much electricity as a built in 220 volts GE oven made in the 1950's

The formula is Volts (X) Amps = Watts. Therefore 1500 Watts at 120 Volts equals 12.5 amps of current (measure of how much energy is being consumed). A standard oven is connected to a 240 Volt supply with a bake element at about 2000 (or so) Watts. That comes to 8.3 amps. Therefore, the oven (regardless of age) is more efficient as far as power consumption is concerned. Also consider the size of the cavity being heated... a toaster oven isn't actually heating as long or as often as a 3 to 4 cubic foot oven cavity, so there the toaster oven wins. Hope this sheds some light for you.

A toaster over heats up faster, but the heat isn't as uniform. Thus, because of the required heat up time the toaster oven would likely be more efficient than a wall oven. Some things just won't fit like a big pizza. Some things may taste better in the regular oven.

Use a toaster oven, convection oven and wall oven in that order for efficiency. Food taste, your choice.