How To Square Quilt Blocks – Half Square Triangles

Today’s post is all about squaring up quilt blocks. Specifically, how to trim up half-square triangle blocks. Not my favourite step in the quilting journey, but, hey, not everything in life is peaches and cream!

Sometimes you just have to hang in there to get to the good stuff!

I remember when I first started quilting I didn’t square up my blocks. Not out of laziness (although there are times I’m tempted to skip it due to laziness!), mainly because I hadn’t heard of the technique, and then, when I finally did, I was a little daunted by it all.

But after finally tackling it, I highly recommend taking the time to square up your quilt blocks.

*This post contains affiliate links, meaning, at no additional cost to you, if you click through and make a purchase, I may receive a commission.

WHY SQUARE UP YOUR QUILT BLOCKS?

Even with really precise cutting, I’m always amazed at how things shift during the block piecing and pressing process.  Plus, you’ve taken all this time to prep your materials and piece your blocks, it would be a shame to have things come together a little wonky when you finish piecing your quilt top.

HOW TO SQUARE UP YOUR HALF-SQUARE TRIANGLE BLOCK

So here’s a quick overview of how to square up a half-square triangle (HST) block:

Step 1

Gather your tools! Everything works better when you are organized. You will need:

• A *self-healing mat (read why I love this one here)
• A *rotary cutter
• A *ruler with a 45-degree line – I love this one
• An untrimmed half-square triangle block
• A garbage to toss all those trimmings!

Step 2

Now that you’ve got your block squaring station all setup, the next step is to line up the 45-degree angle on your ruler with the central angle of your HST block (red line below). 

Once you find that, the next important step is to ensure your block fits nicely/ exceeds your final block measurements.  In this instance, my final block needed to measure 5.5” square. See how there is some extra fabric beyond the ruler.

Before you make your first cut, always double check to make sure everything is lining up nicely.  You don’t want to come this far only to lop off part of your block! 

Step 3

Once everything is nicely lined up and you’ve double-checked your measurements, slice off the excess that is pocking out of the ruler. There one side of your block is squared off!

Step 4

Once you have one side squared up, turn your block so the squared-up edge is at the top.  You can now line up both the 45-degree line and the top straight line, again ensuring your block has a little excess of your final block size on the remaining 3 sides of the block. Trim and continue this approach until all 4 sides have been squared.  As you continue trimming, always make sure to first line up the 45-degree line and all of the trimmed edges.

There. Doesn’t that look better?!

SEE HST BLOCK TRIMMING IN ACTION

Sometimes seeing a technique in action can be super helpful! See how I trim my own half-square triangle blocks in this video tutorial featuring the Pink Lemonade Quilt Pattern.

TOP TIPS FOR BLOCK TRIMMING SUCCESS

Here are some tips for ultimate success in squaring up quilt blocks:

• Take your time. There is no rush. And besides, it’s often when we’re rushing that mistakes happen.
• Remember to find your 45-degree line on your ruler and line that up with the central line of your HST block. This is key!
• Ensure you have excess fabric beyond the final measurement of the block you are targeting.
• Check your alignment twice and cut once. I sometimes triple check. Only because I’ve trimmed too short before and that just bums me out!
• Have a nice sharp blade. Not only is it safer to work with a really sharp blade, but you won’t have to pass over your cut more than once, which your arm and hand will thank you for! Here’s a review on a rotary cutter and blades I’ve been using.
• Make sure your work area is nice and bright.
• Remember to take lots of breaks when squaring up a large number of blocks.

Following these tips will ensure you have a nicely squared up block!

I will admit this process can be a little tedious, especially if you have a lot of blocks to square up at once.  Block trimming is the perfect time to crank up the music or catch up on some podcasts as I’ve been doing as of late!

Plus, you will be so satisfied once you’re all said and done and see a nice big pile of trimmings! Here’s a peak at part of the pile I had after squaring up blocks for my Blue Odyssey Quilt.

Give it a go and let me know how it goes!!

xo

Shannon

---

Never miss a post – sign up for the weekly newsletter.

This post uses affiliate links. For more info, visit the FAQ page.