You can cook as many cobs of corn as your Instant Pot can fit up to the fill line on the inside of the pot. For a 6-quart Instant Pot, I was able to fit 4 large ears of corn. In a larger pot, or depending on your model of Instant Pot, you may be able to fit more. For smaller instant pots, you can slice your cobs into smaller chunks and cook it that way instead. Do not change the process or cooking time.