By having a wider coping you can use the fire pit for more the just a fire pit.
Round fire pit dimensions.
While larger fire pits suited for entertaining groups can be up to 6 feet wide.
Be sure that you leave room to move chairs around and walk behind them.
I like to plan for about 5 feet around the fire pit for seating and access.
So now figure how much room you want to have around the fire pit.
Smaller more intimate fire pits are around 3 feet wide.
So at the 36 inside diameter with say 14 coping that gives us an outside diameter of 36 14x2 64 inches.
If you plan to use the edge of the pit as a sitting wall you ll want it to be about 20 inches.
The exact height you choose for your fire pit will depend on how you plan to use it.
The size of fire pits varies greatly.
For example if you want to be able to prop your feet on it go with one that is about 12 to 14 inches high.
These measurements include the thickness of the walls so realize that the total width of the fire pit is not the same as the width of the burning area.
Lets say 4 for a sitting area and such.
Most store bought units are available in a 24 inches to 30 inch size.
A fire pit itself is rarely bigger than four or five feet across and the patio space around it should be an additional six feet or so on all sides.
If you re choosing low slung seating such as adirondack chairs don t forget to account for the extra real estate they take up.