Although there are no hard and fast rules, I tend to stick to the amount that can fit in a smoker box. This is typically 5 ounces of chips. Remember that temperature, smoker size, and cooking time can affect how quickly your chips burn. Begin with 5 ounces, and if you have to replenish them too frequently (which disrupts the internal temperature of your chamber), or if they aren't imparting enough flavor on your turkey, increase the amount.