Half Square Triangles Made Easy!

by Jennifer Jones

If you're like me, you probably can't decide if you love half-square triangles (HSTs in the quilty world) or despise them. In a quilt--love them! When it's time to make 400...not so much. 

But if you're interested in becoming a better/more experienced quilter, the HST is a shape you need to learn to work with. It's everywhere! In new patterns and old. In simple designs and crazy complex. And there are a few helpful tips to getting this shape just right.

This blog post will give you a few tips in making HSTs using the two at a time method, and also a couple of trimming tricks! 

One of the most basic ways to make HSTs is using the classic 2-at-a-time method. You start with two squares, sew a couple of stitches, and end up with two cute HSTs! Personally, I like this method best because when it comes to trimming, I've found it to be the most accurate. 

So let's make a few! 

Making HST using the Basic Method

1. Begin with 2 squares of the same size. On the wrong side of one, draw a line diagonally from corner to corner. (fig 1) Now pin your squares right sides together (RST). 

 

2. Using the line you drew as a sewing guide, sew 1/4" on both sides of the draw line. Carefully cut along the drawn line. (fig 2) At this point, you'll want to press your pieces open and trim them up, but the method you use depends on you! (and maybe your rulers...)

3. You'll trim your HSTs to the specificied size, using the chart below. 

A chart like this can be super handy, so I made a printable that includes this and some basic directions for making these 2 at a time HSTs. But if you need a size that's not included, all it takes is some very simple math to find the size squares to begin with! 

To find your beginning square size, just add 7/8" to your finished HST (finished means the size it will be when it's all sewn into a quilt). 7/8" is really .875", which is awfully close to 1". So if you're like me and would prefer not to work with weird fractions/decimals and also would like to have a little extra wiggle room when trimming, you might try just adding 1" to your finished HST size. 

Here's the formula: 

Finished HST size + 7/8" = Beginning square size

Trimming

Trimming.....the bane of the HST's existence. I think I know maybe 2 people who actually enjoy this step. But once you find a method (and a few good tools!) you like, it really isn't so bad! And the payoff is totally worth it! 

Also--let's just remember quilting should be a slow art-form (preaching to myself here!!) so bits that let us slow down and stay in the process a bit longer are probably good for us. 

Ok...a few tips and tricks for you for trimming. Really the method you use to trim comes down to rulers. You can go fancy or simple here, so I'll start with simple and work my way down. 

So this is really just another acrylic ruler like the long ones you use for cutting your fabrics. If you purchase a large enough one, you can use it for trimming small to large HSTs. One tip here is to mark your size using some washi/painters tape so that you have a line to line your HST seam against. 
You can use this one a few ways. You can use it once you've pressed your triangle open (pressing the seams open works best for this method). Or you can trim before you've opened your HST. (here's a little highlight from IG showing how)
Pros: 
  • less expensive
  • multi-use ruler rather than specialty
  • multiple methods 
  • works for lots of sizes
Cons:
  • Can be prone to slipping
    Now we're in fancy territory, but also my favorite. This ruler has a notch that will fit snugly against your HST, but requires you've pressed to the dark side. It really doesn't work well if you've pressed your seams open. It comes in a variety of sizes, but they're all around $25, so not cheap. But if you love a good HST quilt, it's worth putting on your wish list! 
    Pros:
    • accuracy
    • ease of use
    • less slippery
    Cons:
    • pricey
    • a bit more specific size-wise (although if you purchase the largest size you normally use, you can definitely trim smaller HST using the same ruler)

      Other Tools I love...
      I try to treat myself to a fresh blade on my rotary cutter when I'm sitting down to trim a large stack of HSTs. It's like putting a fresh needle in the machine--you don't think to do it but once you do you wonder why it took you so long! 

      One of my favorite tools and one that stops people in their scroll every time I share it. (you can see a clip here)  Pair it with a fresh rotary blade and a good blocloc ruler, and I could make these HSTs for days!! 

      If you're interested in more HST trimming help, you can watch my video here for more info! And if you're looking for a good HST quilt pattern, you might be interested in Maizie, Lottie, or Ramona, found in my shop! 
      Ok, I'll be back with a few more HST methods, but hopefully this gives you a good start! 
      best,
      Jennifer
      This post contains affiliate links. If you purchase an item through my link, I receive a small commission from that purchase. There is no additional cost to you, and I promise to always and only share items I love! 

       

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