Warm Cool Quilt Along - Half-Square Triangle Tutorial

Monday, June 13, 2011

This post is a part of the Warm Cool Quilt-Along! Feel free to join in the fun at any time! :)

1. Color Refresher
2. Quilt Sizes and Fabric Requirements
Today's Post: Half-Square Triangle Tutorial

Let's talk Half-Square Triangles! As I've said before, HSTs are a great building block for many different quilt blocks and patterns and therefore learning how to make them is important! I've used lots of photos for this tutorial so hopefully it's clear and easy to following!

1. Take 2 squares, in this case one Warm and one Cool. This is really important for creating the Warm/Cool pattern!

2. Place your squares right-sides-together.

3. Line up a ruler along the diagonal, from one corner to another.

4. Carefully trace a line with a pencil.

5. Using a scant 1/4" seam allowance, sew along one side of the pencil line. I recommend either using a 1/4" foot, or move your needle over so that it is 1/4" away from the edge of your presser foot. This way you can simply line up your presser foot with the pencil line! Backstitch at each end.

To find a scant 1/4" on your machine, use the test outlined in this tutorial at Sew, Mama, Sew!

6. Turn your square and sew down the other side of the pencil line.

7. Using scissors, cut down the pencil line, splitting the square in half.

8. Press your seams. I prefer to press my seams open. I think that it allows the block to lay flatter. For more information on seam pressing check out this tutorial from Sew, Mama, Sew. You can also find an interesting discussion on pressing seams open here.

Now we need to trim our HSTs. For the Mini size, trim your HSTs down to 3". For the Baby and Twin size, trim your HSTs down to 4.5".

9. Place your ruler over your HST with the corner on the diagonal seam. Line up the diagonal line on the ruler with the seam. Carefully trim as little as necessary on both sides.

10. Turn HST and trim the other two sides, again lining up the seam with the diagonal ruler line. This time trim off enough to reach the desired unfinished size HST as stated above.

Woo hoo! You're done! You now have two Half-Square Triangles!

Continue to make HSTs with the remaining squares, making sure to match up one Warm square with one Cool square. Do so somewhat randomly, just making sure that you have some variety in your match-ups!

Note: If you want to make different sized half-square triangles (for other projects!), simply add 1" to the size you want your finish HST to be to get your starting square size. Then trim to your unfinished size. For example, if you want a finished HST size of 2", cut two 3" squares and trim to 2.5" :)

Feel free to add photos of your progress to the In Color Order Flickr Group! If you have any questions please don't hesitate to ask! Next week we'll be laying out our quilt tops!


  1. Thanks for this. Have you seen this method, too?


    I get confused with the size of the finished triangle, but it's a great method as the finished squares are very accurate.

  2. DevonMaid: I love that method, it's actually the way I prefer to make them! For this project however, it's nice to have a greater variety, and this method results in only 2 HSTs that are exactly the same rather than 4. :)

  3. Because we are using so many different colours, and in my case, also lights and darks, what colour thread would you recommend for piecing? I was thinking about using a light grey or neutral.

  4. I just wanted clarify the block sizes. In your previous post about fabric requirements, you specified the HST sizes as 3.5" for the Mini, and 4.5" for the Baby and Twin. In this post you reference 3" and 4"... Shouldn't those be the finished block size (after the blocks are sewn together)?

  5. As Caitlin pointed out, I did have one measurement wrong for the trimming. I have fixed it in the post, for Baby/Twin you should be trimming down to 4.5"! :)

  6. Jeni: What an excellent point about the variety of pairings! I haven't ever done HSTs and was going to ease into them using that other tute, but you're right, I'd rather get more variety this way.

    Side note: after our chat last week, I seriously went and bought like every single FQ you told me about! I got half this weekend and the rest should come tomorrow. I better get to cutting and sewing!

  7. perfect! i'm off and cutting now.

  8. omg...I would have cut the material in to triangles and went from there. This method looks so much easier.....and this is why I will always be just a beginner quilter!

  9. I love HST's (and also did a blog on them!) but they take so long to make...I needed to make a ton for a bunch of sawtooth border I was making, and after trying every method under the sun, I ended up finding a DVD ("Triangulations") which prints off pages of HST sheets. It is super easy, super accurate and super fast! They have a sample sheet you can try.

  10. my question is you have the nice points but how do you keep them once you sew them together you lose the point in the 1/4 in. seam. you no longer have the point.

  11. Any advice on drawing the line perfectly from corner to corner? I keep being just slightly off!

  12. @Jeni I am still confused even after you clarified from Caitlin's post. After the HST are sewn together, when you cut the "ears" off, the size for Mini should be 2.5. The squares started out as 3", right? I just want to make sure I am doing it right. Thanks so much and I love it!

  13. Hi Jeni! Great tutorial, but I can't for the life of me figure out how to get a 1/4 inch seam using my regular foot on my machine. I have a Janome Magnolia and when I line up my pencil line with the right side of my foot, the seam winds up MUCH wider than 1/4 inch. Even if I move my needle ALL the way to the right (putting the width at 5) the seam is still too wide. I really want to use your sew-first-cut-second method of making half square triangles but I'm not sure how to go about it... Hope you can help!

  14. I will make this suggestion, iron the triangles open before you cut. You will have less distortion.


Thanks for keeping this blog a positive place, I appreciate the time you're taking to leave a comment! I'll answer any questions here in the comments section!


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