The microwave safe symbol is a square microwave logo with 3 squiggly lines inside the box. Other symbols used are 3 to 5 wavy lines stacked on top of each other. The squiggly lines are a constant symbol that means you can confidently reheat your food in the microwave with that dish. However, it is important to note that not all containers have a microwave safe symbol. In such cases, you can check the label or the container itself for any indication of whether it is safe to use in the microwave.