Magic 8 Half Square Triangle Method

So when I published the magic eight half square triangle method video over the weekend I never imagined that it would be as popular as it has been.  I've been asked about the method so much that it was time to type it up here on the blog so I don't have to repeatedly type it out over and over.  This is a handy formula, that's the math, to have so no matter how the pattern shows you how to make half square triangles you can make them eight at a time.

magic 8 half square triangles


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Paul and I look at quilt patterns and tutorials completely different.  I watch tutorials on YouTube for inspiration, see what the trends are, and to see what has already been done.  If I buy a pattern it's because I intend to do the pattern the way the designer said.  Paul, on the other hand, looks at the methods and then reverse engineers them so he can use that method anytime he wants.  I don't always break down the math behind what I'm teaching.  For example two weeks ago I shared my way of making flying geese, last weekend bulk half square triangles, and this weekend I'll do a block using those two pieces.  Then in a few weeks, I'll release the whole quilt pattern.  I do this so I don't overwhelm anyone, see you can make flying geese this size, now you can make eight half square triangles at once, now let's make a quilt block, and finally see you can make this big quilt.  I think most designers and teachers approach it this way no matter their method of delivery.  We focus on the end product and then teach the little parts so that you can make the end product but not necessarily how to use the methods in other projects.

This magic eight half square triangle method is really thanks to Paul and the way he views tutorials and patterns.  He had seen this a couple times with different finish sizes but never how to make them any size you wanted.  So he worked the math out backward until he got it just right based on what was available.  I've tweaked the math slightly to cut down on waste but still leaving more than enough to trim.  Let's start by seeing how you make one.



So you can see how easy they are to put together.  The above video is based off of Paul's original formula.  That's the first math formula I'm going to give you.  There was a lot to trim off when I made these smaller half square triangles.  This can be viewed as good or bad, good because if you goofed you have lots of room to straighten it up but bad because you are trimming off a lot of fabric.

Magic 8 Half Square Triangle Method #1

Finished size of half square triangle, this is what your pattern calls for plus 7/8".  Multiply that number by two to get the size of square to cut.  After that you put it together just like the video above just trimming to the desired size instead of 2 3/4".

Magic 8 Half Square Triangle Method #2

This one has slightly less fabric to trim off but still will give you room to trim. 
Finished size of half square triangle, this is what your pattern calls for plus 3/4".  Multiply that number by two to get the size of square to cut.  After that you put it together just like the video above just trimming to the desired size instead of 2 3/4".

I still like the two at a time half square triangle method.  This is great for scrappy quilts and small projects.  If you need to make lots of half square triangles the magic eight method is just much easier and faster.  Don't forget to pick up my preferred ruler to trim up half square triangles. It really does make a world of difference when squaring any block up.

Now some of you may be wondering about how much you will have to trim off.  With method one Paul, the official trimmer of half square triangles, trimmed almost a half inch off.  He was able to make sure all of my triangles perfect.  Method two there was about a quarter of an inch to trim off.  I debated scaling down the method even more but Paul urged me not to.  We were texting about it and he brought up minute of angle and I gave the confused puppy dog look at my phone.  I told him to just explain when he got home.  He tried again with words and this time he saw the look.  Thankfully I had some big half square triangles on the design wall so he could show me.  My little squares I was off just a fraction so in reality I only needed to sliver trim them but that same fraction on the big block I needed a lot more room to clean it up.  So while both methods allow for lots of trimming on a small block if you were making ten inch half square triangles you would need that excess.


As you can see not near as much room left to trim on the purple and white one.  Don't forget to sign up for our weekly newsletter so you never miss out on our tips, tutorials, and more. Also be sure to check out all of our tips to make your sewing and quilting easier.  You can use this as the jumping off point for the hourglass quilt block too.

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About Melissa Shields

Mel is a 30 something year old quilter, attempting to balance her old school roots with today's trends. When not sewing or shopping for a new sewing machine Mel enjoys reading, reality TV, and Nascar.

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