Prepare potatoes for cooking: wash and scrub to clean. Pierce with fork in several places.
Make sure the stainless steel insert is in your IP. Add 1 cup of water to insert and set the trivet inside.
Arrange potatoes on trivet. Close the lid and set valve to "sealing" position.
Press "manual" or "pressure cook" setting and set timer to: 16 to 20 minutes for potatoes that are 6" in circumference OR 26 to 30 minutes for potatoes that are 8" in circumference or more (see note how to measure).
The IP will beep when ready and it will start the cooking process. When the timer is done, let the pressure cooker release the pressure naturally. It will take about 12 minutes.
Carefully open the lid away from your face and remove potatoes from the Instant Pot.
Serve.
Notes
SHORTCUT: cut potatoes in half lengthwise and arrange on trivet, cut side up. Cooking time depends on the size of your potatoes, of course, so read through the recommendations above. While a whole potato that is 8" in circumference cooks in 28 minutes, if you cut it in half it will cook in 14 minutes. It's a perfect portion if you want just half of the potato or for children.How to measure potatoes: take sewing tape measure and wrap around the thickest part of the potato (in the middle). It's like measuring your waist. If you don't have tape, use a string and measure it with a ruler.