Without knowing what your seam allowances were, all I can give you is the straight-up math. Your outside edges are all the hypotenuses of the right triangles. Remember the Pythagorean Theorem: A-squared + B-squared = C-squared (where C is the hypotenuse and A and B are the other two sides).
Side A is 4 7/8" (or 4.875"), and Side B is the same. You want to know what side C is.
4.875 squared + 4.875 squared = C squared
4.875 x 4.875 = 23.765625 so ....
23.765625 + 23.765625 = 47.53125 = C squared
The square root of 47.53125 = 6.8942911 so...
C (the hypotenuse and your outside edges - without having taken into account seam allowances) = 6.8942911" (or roughly 6 7/8")