How to Square up Quilt Blocks

When quilting, squaring up quilt blocks is important. Squaring up blocks helps to keep the entire quilt square. The finished quilt top will lie more flat. The entire quilt will be more even. But squaring up blocks is a pain. It takes time, and sometimes it seems like maybe shaving off all those slivers can’t be as important as getting the project done NOW. But it is. Squaring up is such an essential part of having your points line up.

Here, I’m going to show you how to square up Half Square Triangle, or HST block. Because HSTs are stitched on the bias (an angle across the fibers, instead of parallel with the fibers), it can make the blocks stretch out of whack when you press the block open. I’m trimming these HSTs to 3″. I could use a 3″ ruler, but instead I use a square ruler that is larger than 3″, and just keep an eye on my 3″ mark.

trim block

I also line up the angle of the block with the 45 degree line at an angle across the ruler. This will help all the points line up. I make sure that the block is inside the 3″ mark, then trim off the excess on the two sides, where the block hangs out past the ruler.

The block gets rotated 18o degrees, and then I line up the 45 degree line, as well as the 3″ line both horizontal and vertical. Trim off the excess on two sides, and the block has been squared up!

trim other side

Repeat – over and over and over again… until all your blocks are squared up!

trim half square triangle blocks

That scrappy pile on the right… that’s a whole scrappy pile towards accuracy.