When making a round tablecloth for a table or other round structure, the amount of fabric to be used can be calculated as follows:
Measure the diameter of the table top )or top of whatever round structure is to be covered).
Measure from the edge of the table top down a leg or side, to the endpoint that you want the cloth to fall. This may be the floor; if so, measure to the floor.
To calculate the fabric amount, take the diameter measurement and add twice the length of the fall wanted and you will have the amount of fabric needed.
Note: The pattern may require two or more pieces of the same length of fabric for added weight or durability.