You can run a few small appliances or one large motor-driven device on a 2000W inverter, depending on appliance efficiency, startup surge, continuous draw, duty cycle, and energy storage. For example, two low-wattage items (750W blender + 250W laptop) fit comfortably. Inverter size (Watt) = Total sum of all appliances power (Watt)*1. 150 + 7 + 75 + 150 + 50 = 432W 432 X 1. By. The inverter capacity calculator helps you find the right inverter size for your home or office. This tool reduces guesswork and gives reliable results that support. Each inverter has a maximum power rating, which indicates the amount of AC power it can supply. ⏱ How many hours of backup do you need? Choose.