Hi there. This is the exact measurements you need. But they are a little interesting to cut the sizes.
You would need 2 7/16" squares (4 squares, 2 of each color) sew together to make a 4 3/8" four patch block.
Sew the blocks together you will have 4 3/8" x 8 1/4" block. If you sew 4 4 patch units together you will have a 8 1/4" block.
Or you could sew 2 1/2" blocks together and trim to 4 7/8".
Pinwheels are another story.
) Place 2 different 2 13/16" squares right sides together. Draw a diagonal line from corner to corner. Sew 1/4" on either side of this line. cut apart. Do this twice and you will have the 4 squares for a pinwheel. Sew together to make a 4 3/8" pinwheel. Or you could use 2 7/8" squares and again you will trim the finished pinwheel to 4 7/8". These are interesting measurements, but it should work out! Ann