PaperPrincess

I got the 20.5" on sale. While it's great for squaring up tops and backings, it's too unwieldy for anything else. if you don't make anything larger than a 12" finished block, I would get the 12.5" ruler. While you can always use the larger ruler on smaller blocks, it is soooooo nice to have the exact size. I waited for sales and eventually got the 8.5 and 9.5.

QuiltnLady1

Depends on what you want to square up. If it is a block, get one for the size of block you make most -- I have them from 3.5 - 12.5 because I also use them to fussy cut blocks. If you are squaring up your top/quilt after quilting, then I would go with the 20.5 if you can afford it. That said, I used the 6x24 ruler as my square up ruler for many, many years.

Feathers-N-Fur

My vote is get a 12.5" then add the other sizes when you want to. I made a sampler quilt with 50 8" blocks. It was well worth it to me to buy the weird sized 8" square up for that one quilt. But I didn't get it until I needed it because it isn't a common size.

Chasezzz

My vote is 12 1/2" as well. That should handle all but very large blocks. And my brand vote is Creative Grids. They are so well marked and do not slip...I have abandoned my other brand rulers for Creative Grids.

donnajean

I've never used anything but the 12.5 square. I square up the corners then use the longer ruler for the sides if it is a bigger quilt.

todiesmom

I like the 15 1/2" square because i make a lot of totes and it is perfect size for cutting out and squaring up....I also have a 12 1/2" and 9 1/2 inch which I use a lot.

AZ Jane

I have and use a 20" square ruler for squaring up a quilt. Any size will do for squaring up individual blocks.

mhollifiel

I discovered this tutorial about rotary cutting that uses a big square ruler. I LOVE it! Even though I have a GO strip cutter, this is the method I prefer using my 15.5" ruler. Fast and accurate. It has turned my 12.5 and 15.5 rulers into essential tools for cutting as well as use in squaring up, etc. I have smaller square rulers but seldom use them anymore.
Here's the tute:
https://www.youtube.com/watch?v=NoBKOv3Azzw

Kitsie

I have a 12" but rarely use it. I love my 6" and 3" for the kind of patterns I like.

bearisgray

It makes sense to use the tools that make the job easier.

No point in getting a back-hoe for a job that a shovel would be more efficient.