To determine if baked potatoes are done without opening the oven door, you can use a few alternative methods to gauge their doneness:
Fork or Skewer Test: Carefully insert a fork or a wooden skewer into the thickest part of the largest potato. If it slides in easily and the potato feels tender, it's likely done. If there's resistance or it feels firm, the potatoes need more time.
Temperature Probe: If you have an oven-safe meat thermometer with a long probe, you can use it to check the internal temperature of the largest potato. The ideal temperature for a fully cooked baked potato is around 210°F (99°C).
Timer: If you know the approximate baking time and temperature for your potatoes, set a timer accordingly. When the time is up, the potatoes should be close to being done, depending on their size and your oven's accuracy. This method is less precise but can still give you a rough estimate.
Remember that the cooking time for baked potatoes can vary based on their size and the oven temperature. If you're baking multiple potatoes, they might not all be done at the same time. You can always remove the smaller ones and let the larger ones continue baking if needed.