I have enjoyed the you tube video to make pinwheels from two squares sewn together a 1/4 inch all the way around the outside edge. I would like to have a chart that shows you what size blocks to start with to end up with a 5 inch pinwheel and a 6 inch pinwheel. Can any help?

http://www.quiltingboard.com/t-57124-1.htm#1377835
Maybe this will help:)

This only goes up to 7". I want to know what size to cut for a 10" (10 1/2" with seam allowances) block. Can anyone help?

On the last 4 measurements she gave, there was a difference of 3 inches between the square she started with and the ending size. So I would try 14 inches and see if that is slightly too big. Easier to make it smaller than make it bigger. If 14 is too big, try 13.

When we were doing the pinwheel project a member, Ceil, came up with this formula that works!
"Whatever your block side is subtract .5 then multiply by 1.4 then subtract .5. "

Starch or sizing the fabric is a must before you cut out the squares.

So you would have:

to end with a 6" block
Start with 2 5.5 inch squares
5.5 minus .5 = 5
5 x 1.4 = 7
7 Minus .5 = 6.5 unfinished block = 6" finished

To get a 5"
Start with 2 5 inch squares
5 - .5 x 1.4 - .5 = 5.8 trim to 5.5 unfinished = 5" finished

Try it on some scrap fabric.
If your seams are a true 1/4" it should work.

HTH

You would start with 8.5"
8.5 -.5 x 1.4 - .5 = 10.7 trim to 10.5

Test it with scrap material!
Starch the fabric before cutting since you are working with bias edges.
HTH

Thank you for posting this. I found it very helpful.

One thing I discovered using this method was This gives you the size one on the 4 pinwheel blocks, then you put them together to make your pinwheel or what other shape/ pattern you want. I was trying to make a 4" pinwheel, followed the above for a 4" block and ended up with an 8" pinwheel once all pieces were put back together. So you want your "block" to be 1/2 of the finished pinwheel size. 10" pinwheel would use 4 5" blocks. (Just rough measurements as an example) When you are cutting up your square you are making 1/2 sq triangles not the pinwheel. The pinwheel comes from the 4 cut blocks re sewn.

http://www.moonlightquilters.org/tipHSTfav.htm

Is another site with sizes for the HST.

I'm still new at this but it was something I learned the hard way.