Easy Half Square Triangle Blocks

This free tutorial will show you the way to make easy Half Square Triangle blocks from two squares of fabric rather than from a triangle shape!

Half square triangles are also referred to as hst blocks or hst units.

Even if you’re a new quilter the different ways to make these basic blocks will let you have a finished quilt in no time flat!!  HSTs were the first blocks I learned how to make!

Using this basic method you’ll get two HST blocks at a time!

I especially love this alternative method versus the traditional method as it’s sometimes hard to cut the correct size of triangles and then sew them together along their bias edges without the block ending up all wonky!

Plus it’s a saving fabric and saving time method as you can make two half square triangle units at a time and there is just a little bit of fabric waste!  

Learning how to make a half square triangle quilt block this simple way will let you make a lot of hst at a time! 

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What are Easy Half Square Triangle Blocks?

Half-square triangles are versatile quilt blocks that can be arranged in different layouts to give you different patterns in your quilt.

Half Square Triangle blocks are made up of two equal right triangles sewn with a diagonal seam to create triangle squares.  They are a square block with two triangles laying on their side!!

Items You’ll Need to Make Easy Half Square Triangle Blocks

There are just a few basic items you’ll need to make easy half square triangle blocks!!

You’ll need to have the following items:

  • Pencil or Washable Marking Pen
  • Plastic Quilt Ruler
  • Scissors or Rotary Cutter
  • Straight Pins
  • Iron and Ironing Board
  • Two Equal-Size Squares of Contrasting Fabric
  • Sewing Machine and Thread

Instructions for Making Easy Half Square Triangle Blocks

Follow these easy steps to make two half square triangle blocks at a time!

Step 1 Fabric Choices

Choose two different fabrics to use for your HST blocks.  You’ll want to have contrasting fabrics to give you the best results! 

A good way to determine whether your two fabrics have enough contrast is to take a picture of them together. 

Edit the picture to be in black and white. 

If you can’t tell much difference between the two white and solid black fabrics then you probably don’t have enough contrast between the two fabrics!

Step 2 Cut Two Squares

Determine the size to cut your fabric.  To do this you’ll need to know the size your unfinished hsts need to be.  Unfinished measurement should be indicated in whatever quilt pattern your following. 

Add 1″ to the size needed.  Cut one 1″ larger square than needed from each of the two fabrics chosen. For example, if you need your unfinished HST to measure 2 1/2″ square, then cut your two 3 1/2 inch squares of fabric. 

You’ll trim the squares to the size needed later!

I love to use the Fiskars contour grip rotary cutter, a Fiskars Self-Healing Cutting Mat, and the Omnigrip 8 1/2″ x 24″ ruler to cut my fabric to the correct size!

(insert pics and links)

Step 2 Mark, Sew, Cut, Press

Use a pencil or washable marking pen and a ruler to draw a diagonal line from corner to the opposite corner on the wrong side of the lighter of the two fabrics chosen.

Pin the two squares together, right sides facing, with the darker fabric on the bottom. 

With the drawn line facing up, use a straight stitch and a 1/4 inch seam allowance to sew along both sides of the center line. 

Cut the two blocks apart along the line to give you two HST. 

Press seams of each HST open toward the darker fabric.  I always set the seam first with the dark side facing up, then open up the HST to press it.

Step 3 Trim the Easy Half Square Triangle Blocks

Use a small ruler to trim the blocks into smaller units the exact size needed, and trim off the dog ears!

What is a dog ear?

Dog ear points are those little triangle shaped corners that extend beyond the edge of the untrimmed square.

I like to use the Easy Square ruler to trim my HST blocks!

Find the two horizontal and vertical lines on the ruler that are the size you need your HST to be.  Then, find the point where these two lines intersect on the ruler.

For the sake of explanation, I’m going to be trimming my HST to measure 2 1/2″ square.

Find where the 2 1/2” horizontal and vertical lines on the ruler intersect. 

Place the ruler over the HST, aligning the 45-degree line on the ruler to the diagonal seam and the 2 1/2” intersecting point on the ruler to the inside corner of the HST. 

Make sure a bit of the fabric extends beyond the 2 1/2” lines and beyond the outside of the ruler. 

Hold the ruler steady and trim the right and top sides of the HST. 

Turn the HST around so the corner you just trimmed matches with the 2 1/2” intersection point on the ruler and the 45-degree diagonal line on the ruler aligns with the diagonal seam of the HST. 

Trim the other right and top sides to give you the exact unfinished size needed!!

Repeat for the other HST unit!

Voila!  You now have made two Easy Half Square Triangle Blocks to use in your quilt!!!

Types of Quilt Blocks Using Half Square Triangle Units

The HST is one of the most versatile quilt blocks!  There are several block patterns or quilt designs that can be made by arranging HST into different designs!!

One of my all-time favorite quilt blocks that uses HST is the Bear Paw block!

bear paw quilt block

You can use HST as the points in a star block or a feathered star block.

HST rotated into four different directions form a pinwheel block.

Place HST together to form a flying geese design.

Northwind blocks are made up of HSTs!!

Use HST to make Quarter Square Triangle Blocks!

Sometimes you might want to add a border to your simple quilt to make it larger.  A great way to do this is to use HST placed around the entire quilt as a border!!  If you place HST together in the same direction and sew them into a long row it makes a lovely quilt border!!

The sky is the limit for all the different designs you can make using Easy Half Square Triangle blocks!!!

If you are interested in another good way to use HST check out my blog post of my Sweet Emily modern look quilt or my Carnival baby quilt patterns, or look up my Barefoot mini quilt pattern on Etsy!

Check me out on social media @lakegirlquilts on Instagram or lakegirlquilts on Pinterest!!

Enjoy and happy quilting!  

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