Got some really nice Moda Fabric cheap and decided to to do a Rail Fence using 4 fabrics. I sewed the all 4 together and cut two 8 inch blocks. When I turn them to make the Fence, they dont line up. One side measures 8 and one side 8 1/4, so you cant sew them together. What did I do wrong? Im not a math wiz so its a problem. Appreciate any input you can give me.

What size did you cut your strips before you sewed them together?
It sounds like your seams, the size you cut the blocks, or the strip size could be the culprit.

After you make the strips and if they are conistent in width then you cut the block that size. If all came out to 8 1/2 then you would cut 8 1/2" Or if they all were consistent at 8 1/4 then cut the square 8 1/4
Rail fence is flexible in size just as long the block is square. In your example they should have been cut at 8". Your blocks will be a bit smaller than planned but if all are square then it is ok.

they were all 2 and 1/2 inch strips and I used a 1/4 inch seam

sounds like you must trim them to the same size. then put together. good luck.

The strips sewn together should be 8 1/2" wide. If the strips were all 2 1/2" you may double check your 1/4" seam. You can work with what you have just when you trim make sure you trim from the same side each time. Good luck!

I had the same problem one time. Turned out my 1/4" seam wasn't really 1/4" - it was between 1/4" and 3/8" (closer to 3/8"). I'd been using the edge of my presser foot as a guide, but had never checked to see if it was actually 1/4"! If your 1/4" seam is off by as little as 1/16" - whether wider or narrower - that can make 3/16" difference (almost 1/4") in the measurement of your block when you hae three seams.

The other possibility is an inaccurate ruler or perhaps cutting the strips just a little wider or narrower than 2-1/2". That also would throw off the measurements of the finished pieced square.

Good luck!

I ran into the same problem, but my pieces weren't big enough to strip piece so I had to sew each block individually. One side was 12 inches, the other 12 1/4. And I couldn't fix it, but as it is for my bed, I don't care. I sewed them together anyway and let me say, when you have 4 pieces, you can't really tell when they don't match up. You have to look quite close to see them. BUT I'm glad to hear I'm not the only one with this problem!

You need to measure the sewn sections together before you then cut these strips into the blocks. Your 4- 2 1/2 inch strips sewn together measure 8 1/2. You then need to cut the blocks 8 1/2 inches instead of 8. You just forgot to add the seam allowance (1/4inch each side) to your cut.....

Easy to fix, just cut 1/4 inch off each side of your blocks to make then 8 inch square.

Good luck!