Half Square Triangles (HST) are popular in traditional, modern and contemporary quilts. There are several ways to make these basic quilting blocks, one at at time, two at a time and eight at a time — and I’m sure even more! This simple method makes four half square triangles at a time.
It is an easy technique, but you need to be cautious as all four outside edges of the finished blocks are on the bias and can easily be stretched. I personally prefer to have the outside edges be straight of grain — but this method is easy if you only need four blocks!
Half Square Triangles Four at a Time Calculator
When you make these four at a time, it is not exact like it is with making 2 or 8 half square triangles at a time. Always round up from this calculation: Finished half square block size divided by .526. Example: for a finished 3″ half square triangle block, 3/.526=5.7. So, round up to 5.75 or 5-3/4. Then you’ll need to trim your block to 3-1/2″ before sewing together. Here is a cheat sheet for cutting and trimming your fabric for half square triangles four at a time:
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- 1″ finished block, 1/.526=1.9; cut your fabric at 2″ and trim cut blocks after sewing to 1-1/2″
- 2″ finished block, 2/.526=3.8; cut your fabric at 4″ and trim cut blocks after sewing to 2-1/2″
- 3″ finished block, 3/.526=5.7; cut your fabric at 5-3/4″ and trim cut blocks after sewing to 3-1/2″
- 4″ finished block, 4/.526=7.6; cut your fabric at 7-3/4″ and trim cut blocks after sewing to 4-1/2″
- 5″ finished block, 5/.526=9.5057034; cut your fabric at 9-5/8″ so that you have a little room to trim and trim cut blocks to 5-1/2″
- 6″ finished block, 6/.526=11.4; cut your fabric at 11-1/2″ and trim cut blocks after sewing to 6-1/2″
How to Make Half Square Triangles Four (4) At a Time
Learn how to make half square triangles four at a time with this quick and easy technique to make this popular quilt block. Sew four sides of a square, cut and press!
Half square triangles are a basic block in many quilt designs. With this method, you can make four (4) quickly and easily.
Materials
- Two squares of fabric cut to the chart above or use the formula for other sizes
- Thread
Tools
- Sewing machine
- Iron
- Ironing board or pressing mat
- Rotary cutter
- Quilters rulers
- Bloc Loc ruler for block size (Optional, but very helpful)
- Rotary cutting mat
- Rotary cutting mat on turntable
Instructions
- Cut two squares the right size for your finished quilt block. See the chart above. I'm making 3" finished quilt blocks so am starting with two squares that are cut to 5-3/4".
- Layer the squares right sides together, matching all four sides and sew all around all four sides with a 1/4" seam allowance. Use a 1/4" foot for your machine. On a Bernina it is foot #37 or #57. Here I am sewing the first side together.
- Continue to sew all four sides together with a 1/4" seam.
- Here is the finished 5-3/4" square sewn on all four sides.
- Take your quilters ruler and rotary cutter and cut diagonally across the square, from corner to corner.
- Cut diagonally the other direction to form triangles.
- Open them up and press to make half square triangles.
Be gentle while pressing, as all four sides are on the bias and can easily stretch. - You'll see that the square is a little larger than the 3-1/2" square we want for a 3" finished block size.
It is measuring about 3-3/4". - Take your ruler and line the 90 degree line on your diagonal seam. Measure to 3-1/2 and trim both sides. If you have a smaller square ruler, it makes it easier. Also, if you have a cutting mat on a turntable, it makes it easier.
If you have a BlocLoc half square triangle template for the size of block you are making it is super easy! BlocLoc rulers have a groove that is perfectly placed to line up the seam from corner to corner and keep the ruler firmly in place while cutting. - Here are the four half square triangles all trimmed and ready for my patchwork project!
Notes
Tip: If you plan on making a lot of half square triangles, it is worth the investment to buy the BlocLoc set of templates for quick, easy and accurate trimming.
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There are so many ways to use half square triangles in your quilting. They can be placed together similar to the flying geese pattern:
Put together to form big V’s:
And, even making a herringbone design with your quilt blocks:
Check out how to make half square triangles two at a time, and eight at a time.
