Another branch of New Leaf Stitches

Perfectly Pieced Half-Square Triangles: Without Drawing Lines

Half-square triangles set

There are so many different ways to make half-square triangles that sometimes I think we need to step back and revisit what really works, what’s the quality of the outcome, what uses our resources (time, fabric, $) the most efficiently, etc.

For instance, the “quick” method of sewing a 1/4″ seam around all the edges of the squares and then cutting them on the diagonal, in my opinion, is cringe worthy! Why?  Because all four sides have a bias edge.  Bias=stretch. I heard one new quilter say she used this in her first quilt.  She was so embarrassed of how misshaped it was she never brought it to her quilter. She followed this up with a statement saying she wished she had known better because she wasted her time and money using this technique.

Cringe worthy half-square triangles on bias

With that “policing” out of the way,  I’d like to share tidbits on how I prefer to make half-square triangles, especially creating accurate, small pieces.  Sometimes you will see this method referred to as the Magic 8 Method because from 2 squares of fabric you will end up with 8 half-square triangles.  The basic technique is the same, but I’m hoping you will learn something new on how I get to the end result. So let’s get started.

Magic 8 sewing lines

Because we are dealing with such small pieces, I prefer to heavily starch my fabrics. If I’m using a small amount of fabric, I will use spray starch, but if I have yardage I will use old-fashion liquid starch.  I dilute it in a wallpaper tray and then easily saturate the fabric by doing an accordion fold.  Once the fabric is close to dry, press it well.

Starch fabic half-square triangles

For this tutorial we’re creating 1″ finished half-square triangles.  I cut my fabric squares 4″ x 4″.  IF you’re a math geek and IF you sew absolutely perfect seams, the mathematically correct size would be 3-3/4″.  There is such a minute amount of waste that I like to hedge my bets a little bit for the sake of accuracy.  By the way, at the end of the article you will find a cutting chart for creating different size half-square triangles.

I’ve discovered the majority of you feel the same way as I do:  you HATE to draw lines.  Besides the time factor, those lines don’t always turn out to be straight or accurate.  So, we will be using the “cling” template called, Clearly Perfect Angles. This is a popular, positiviely reviewed notion.

7.CPA Aurifil

Let’s sew…..We want to stitch two seams on the diagonal, 1/4″ from the points, first in one direction and then the other.  This picture is showing you the alignment of the fabric on the gray-bands (There are several techniques you can use with the Clearly Perfect Angles, but for this we want to use the gray-bands). Basically, the points that follow up the outside edge of the vertical gray band are 1/4″ away from the needle/stitching line. Sew one seam and simply rotate the squares 180°, realign and sew a second seam, 1/4″ from the points.  Makes sense, right?  And you didn’t draw any lines!  Yippee!  (see end of post for a discount code)

alignment half-square triangles quarter-inch

This second picture is actually at the machine.  The first two seams have been sewn, but we need to sew a second set of seams on the other diagonal. (By the way, it’s easy to chain-piece these).

Second Alignment Clearly Perfect Angles half-square triangles

Now that the stitching is done, cut the squares in half, first from top to bottom and then side-to-side. For this example the cuts are 2″ from the edges.

First cut 8 half-square triangles

Second cut 8 half-square triangles

Next, cut the squares apart between the seam lines.

8 half-square triangles cut apart

Here’s a hint: you can stack these and cut several at a time!

Cut apart between stitching lines half-square triangles

Now it’s time to trim the half-square triangles to size. Many choose to press the hst open and then trim.  Of course, there are many specialty rulers for this.  Most of the trimming techniques for this require cutting two sides, rotating the squares, realigning and trimming the last two sides.  My preference alleviates some of this.

Leaving the squares unpressed, and knowing we need 1-1/2″ unfinished squares, place a square ruler on the triangles so that the 1-1/2″ markings are right at the seams.

[Edited] Since I originally posted this, I’ve developed a set of rulers that makes squaring up with this method super easy, fast and accurate.  Please check out the Clearly Perfect Slotted Trimmers.  They’ll make your life so much easier!

Trimming alignment half square triangles

Some of you may want to add a piece of tape to help with this alignment.

Trimming alignment tape half-square triangles

With two strokes of the rotary cutter, you can now cut all four sides of the square…..accurately!

Trimming sides half-square triangles

You can see that even after snipping the dog-ears, there’s very little waste.

Trimmed clipped half-square triangles

Press the seams to one side.  In this case, they’re pressed toward the white.

Look at how accurate the half-square triangles turn out!!

8 half-square triangles

Unfinished Half-Square Triangles

Half Square Triangles accuracy

Finished Half-Square Triangles

Try it!  You’ll like it!!


FAQ that I get when I’m traveling around the country teaching this technique are:

When you have many hst to make, why not use the printed paper that you sew through? Why not draw your own grids on a large piece of fabric? 

    In a nutshell….Although the paper is accurate, getting it pinned flat on the fabric can be an issue.  Also, you need to purchase many for each size that you want to make, so I think this gets to be cost prohibited (although the quilt shops might prefer you spending more on several sizes versus one product [Clearly Perfect Angles] that has many uses).   And, I hate to rip/pick apart the paper just as much as I dislike drawing lines! 

     Cons for drawing grids:  1.  you’d need to find the dimensions  2.  you’d need to spend A LOT of time drawing the grids out on your fabric 3. you might want to consider using a walking foot so the fabric doesn’t distort, especially thru the middle 4. The Magic 8 method is simple, accurate and quick.  You would probably have all of the hst stitched by the time you got the grids drawn.  So why bother….

How do I sew a scant 1/4″ seam with the Clearly Perfect Angles?

    This is asked at every event I’m at. First of  all, to be clear, you CAN sew scant seams with the Clearly Perfect Angles.  The product was developed on a CAD program so you can be assured that the seam guides are accurate.  Begin by making sure the needle on your machine is centered.  Follow the instructions for aligning the CPA to your machine bed.  To sew a scant seam (take into consideration: fabric thickness, thread, etc) you will simply move your needle one way  or the other, depending on the technique you are using at that time.  Now you would follow the lines with your fabric points exactly as described in the instructions.  If you ever have any  questions, please feel free to email me!

Magic 8 Half Square Triangle chart

If you’re unable to find the Clearly Perfect Angles at your local quilt shop, please visit and I will be happy to send you one.  10% Discount with code:  Magic8plus2

15 Responses to Perfectly Pieced Half-Square Triangles: Without Drawing Lines

  1. CaroleAnne says:

    You need to use the four diagonal cut HST method when using 10” squares. I starch the squares to have minimize stretch.

  2. CJ YOUNG says:

    I agree with you on the around the edge method. I am happy some people have no problem with it. Like you said, BIAS EDGES STRETCH. I was shown the method you showed us, but TWEAKED it just a bit. I pinned my FABRIC together & drew out the desired SQUARE SIZES in 4 rows & 6 BLOCKS to each row. My HST were 3″ FINISHED SIZE. Then marked all the CUT LINES then marked the SEW LINES. I cut two rows off, for ease of handling. Sewed ALL THE SEWED LINES for those 2 ROWS. Then, repeated process. When I finished sewing all my ROWS, I cut all the BLOCKS APART & then CUT ON THE CUTTING LINES OF EACH BLOCK. WALLA!!! 192 HST & SQUARED UP as you did. SO TIME & SEWING EFFICIENT!!!

  3. Patti Beam says:

    Gosh, Since I found it I use the sew around the edge method all the time with no problems. Couple of things: starch very well before cutting square and handle carefully. Only once did I have an issue and it was because of the way I “ironed” my material. Just so much faster for me.

  4. Quilting in TX says:

    Makes sense. Just the other day I was going to try the 1/4-inch method for a chevron quilt. Think this will work better!

  5. Joy says:

    I love the magic 8 technique and I use it often. I also use the sew around the edge technique and that works as well. Any issues I had with that method were purely user error.

  6. Cindy says:

    Hi Kari, thank you so much for all the instructions and photos on the Magic 8 method. I can’t imagine all the time it took for you to do this for us. I use the same guide you do.

  7. Judy says:

    I have made two large quilts using the sew-around-the-edge technique and had no problems at all with them not being square. I love this method for HSTs.

  8. Danette says:

    I always iron my fabric to a light fusible web before I cut out the squares to make the triangles. I happily use the sew around the edges method. Perfect.

  9. Annemiek says:

    If you cut your starting square on the bias, your hst will be straight!! Simple!

  10. Gayne Barlow=Kemper says:

    I just completed a baby quilt using the sew around the square technique. I had no problems with the bias edges. I was careful,did not stretch the material, pressed, did not “iron”, and all the points of my pinwheels matched perfectly. This is the first time I used 1/2 square triangles, i am a new quilter. I went slowly and carefully and everything worked perfectly. I also put two inch strips around each side of the pinwheel to stabilize the bias edges, so I wasn’t sewing bias to bias. I will continue to use this technique as I found it simple and quick. I needed no extra special templates. Cut carefully, sew carefully and use some sort of fabric stabilizers and it is a breeze.

    • Judy says:

      I’m glad you had success using this method. I learned very quickly that I needed to square up my blocks when I used this method. I no longer make 1/2 squares this way. No matter how I make 1/2 squares I square them up giving me perfect finished blocks.

  11. Emma Carpenter says:

    thanks for the information. I always fretted about using tye sew around the block method because of bias.

  12. Dolores says:

    Love all this information, just finished the most half square triangles I have ever made.

  13. Candace Strong says:

    Can I make larger hst using the 8 at a time method and the CPA template? I don’t have an extension table.

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