Besides thinking about the safety and legal aspects of owning a fire pit, you’ll probably also wonder what size fire pit you need and how deep should the fire pit should be. If you choose a portable fire pit, the size will be predetermined. However, if you’re putting one in the ground or having it constructed, you’ll need to set the fire pit dimensions. What to Consider When Choosing the Size of your Fire Pit: How many people do you want to be able to sit around it? Are you creating a more intimate space, or is it meant to entertain large groups? How big is your patio or landscape where you will add the fire pit?