It depends on how large a king size quilt you want. it could be 102x102" to 120x120"
A snowball could be thought of as a 9 patch variation, so 12" blocks would be easier, and 9patch blocks would work better than 4 patch block for the second block, using with 4" finished size using 4.5" squares.
For a 120" quilt, you would need 120/12" blocks or 10 blocks across and 10 blocks down for a total of 100 blocks, half of which are snowballs and half 9 patch.
For the snowballs, you can get 3 blocks from one WOF
So, 50 blocks / 3 per WOF = 17 strips of 12.5"
17 strips x 12.5" = 212.5" of fabric/36 in/yd = 5.9 yd, round to 6 yd
For the corners on the snowballs, you need either 4.5" squares or 4.75" half square triangles.
You can get 8 squares for half square triangles from one WOF (calc at 5")
You need 4 triangles per block /2 triangles per square x 50 squares = 100 5" squares
100 squares / 8 per WOF = 12.5 round to 13 strips 5" wide
13 strips x 5" = 65" /36" per yard = 1.8 yd, round to 2 yd.
The advantage of using the squares instead of half square triangles, is that you can sew a 2d seam 1/2" from the first seam (toward the corner) and end up with bonus blocks of half square triangles.
That takes 4 squares per block, so 50 x 4 = 200 squares at 4.5"
You can get 9 squares per WOF.
200 squares / 9 per WOF = 22.2 round to 23 strips at 4.5"
23 x 4.5" = 103.5" / 36" per yard = 2.9 round to 3 yards.
For the 9 patch blocks, you need 50 x 9 patches = 450 squares 4.5"
450 squares/9 per WOF = 50 strips 4.5" wide
50 x 4.5" = 225 " /36" per yd = 6.25 yd, round to 6.5 yd
This yardage can be divided however you plan the 9 patches