the inverter has rated power and peak power. Generally, the peak power is twice than the rated power.
If it is a resistive load appliance, as long as the rated power of the inverter is greater than the rated power of the appliance, the load can work normally. For example,we can let 250w computer works with 300w inverter normally. 
If it is an inductive load appliance, the rated power of the inverter is larger than the rated power of the load, and the actual power of the inverter is also larger than the peak power of the load, so that the load can work together normally. For example, the peaking power of 350W electric drill is 1400W, then we can use an inverter which has 800w rated power (its peak power is 1600W)