I cannot put an exact figure on this as it will vary, but it’s less than you might think or fear.
The wood chips are to provide smoke only, they aren’t for providing heat. You only need a handful or two at the start of the cook to provide smoke for anything from 1 to 6 hours, depending on the model of smoker you have, the heat you cook at, and the capacity of the wood chip tray.
Also, once food exceeds 145 degrees Fahrenheit, it stops taking on smoke, so you do not use wood chips for the entire cook, only at the start.
Learn more in our article looking at wood chips and electric smokers.