I searched online for the One Seam Flying Geese and I found the math
here but I'm copying and pasting what that person wrote for it...
Here’s the formula:
Sky Squares = Finished height + ½”
Geese = Finished height + ½” x Sum of two (raw edge) height squares – ½”
For example, my finished flying geese unit is 3 ½” x 7 ½”. I cut my sky squares 4” ( 3 ½” + ½” = 4”) and my geese rectangle 4” x 7 ½” (3 ½” + ½” = 4” height and 4” + 4” = 8” – ½” = 7 ½” length).
For the 5 minute block that is not a flying geese unit, in the youtube video comments she states
5 1/4" x 10" for large blocks or 2 7/8" x 5 1/4" for small blocks.
I did the math (I do love my simple Algebra) 5.25 over 10 equals x over 5.25 You multiply 5.25 by 5.25 and divide by 10 which gives the smaller size being 2.756 in the world of decimals not in the inch world so she rounded up to 2 7/8 for the size I hope I haven't lost you guys yet...
I'm not sure how big the block is when it's done. The math can be done for the finished size as well as long as we know how big it is when it's done... but that's for another math lesson lol.