Maggi used 8m square of fabric to make a square quilt What were the dimensions of the quilt?

If Maggie were making a wholecloth quilt then the quilt would be 8m square, 2.8m along each side. Assuming that Maggie used a different fabric for the backing.

If Maggie were making a quilt that was pieced then it would depend on the size of the pieces cut to form the blocks. Since each cut piece would use fabric to make the seam allowance. Unless we know the design this is truly impossible to answer

This question falls into 'how long is a piece of string' category.