First and foremost you need to decide on the size of your pit. After this you’ll be able to accurately calculate how much room you have to play with for your seating area.
If you don’t have your fire pit yet then you can use chalk to mark where it will be, and use this as a guide.
The key thing to keep in mind is that fire pits are supposed to be enjoyed from all angles, meaning that it should be comfortable to sit facing it from any angle.
Keep in mind that some people prefer to be closer to the pit, or further away from it. Bearing this in mind, try to allow enough room between the chairs and the pit to accommodate this, as well as behind the chairs. Also, try to leave enough room for people to walk between chairs without having to squeeze.
As a rule of thumb, Landscaping Network recommends leaving about 7 feet around the outer edges of the pit, which would allow enough room for foot traffic and furniture. As Landscaping Network says, it’s better to have too much room than too little!