Tutorial + Formulas: 3 Easy Ways to Make Half Square Triangles (HSTs)

The Half Square Triangle (HST) quilt block may be one of the most basic blocks but there are so many ways to make them!

Recently I revisited my Sun Salutations quilt pattern (a quilt entirely constructed out of HSTs) and did a bit of math to make a smaller version. Once you know the basic formulas and ways to make a HST, it’s a snap to make these blocks!

Sun Salutations is the perfect gift for the beach lover or yogi in your life. Make this bright, colorful, modern quilt as a reminder of vacations or trips to the beach. This easy, beginner-friendly pattern is a bright, modern twist on the traditional half square triangle quilt. Sun Salutations is a fully tested pattern that contains detailed instructions and diagrams, making it a breeze to piece.
pattern: Sun Salutations by Whole Circle Studio. Get it here!

HERE ARE 3 WAYS I MAKE HALF SQUARE TRIANGLES (HSTs):

1. Making 2 HSTs at a time (“two-up method”):

Determine the size you want your unfinished HST block to be (the size before you sew your blocks together, taking into account your typical ¼” seam allowance). Add 1″ to that number. This is the measurement you want to cut the squares to make your two half-square triangles.

formula:

UNFINISHED HST BLOCK + 1″ = SQUARE SIZES TO MAKE HSTS USING THE TWO-UP METHOD

example:
Half Square Triangle formula, making 2 HSTs at a time
Half Square Triangle formula, making 2 HSTs at a time

* When making half-square triangles, I always like to square up my blocks before I use them. I find that this helps make block alignments precise and enables me to have better results when piecing my half-square triangles together. I also make my HSTs with more fabric than some other quilters do. While there is a bit more waste, adding this extra amount makes for a less frustrating trimming experience, especially if my ruler slips a bit and I need to make a second cut. I recommend making a couple of test HSTs before cutting all of your fabric. You may find that you are comfortable starting with smaller squares of fabric.

how to make 2 HSTs at a time:
Tutorial: How to make 2 Half Square Triangle (HSTs) at a time

After stitching and trimming on the line between the stitches, press seams. I like to press the seams on my HSTs open. Then, square up your HST blocks to your desired size.

 

2. Making 8 HSTs at a time (sometimes called the “Magic 8” method):

Determine the size you want your unfinished HST block to be (the size before you sew your blocks together, taking into account the ¼” seam allowance). Add 1″. Then, multiply that number by 2. This is the measurement you want to cut the squares to make your half-square triangles.

formula:

(UNFINISHED HST BLOCK + 1″) X 2 = SQUARE SIZES TO MAKE HSTS USING THE “MAGIC 8” METHOD

example:
Half Square Triangle formula, making 8 HSTs at a time — Magic 8 quilt block method
Half Square Triangle formula, making 8 HSTs at a time. Magic 8, quilt blocks

* When making half-square triangles, I always like to square up my blocks before I use them. I find that this helps make block alignments precise and enables me to have better results when piecing my half-square triangles together. I also make my HSTs with more fabric than some other quilters do. While there is a bit more waste, adding this extra amount makes for a less frustrating trimming experience, especially if my ruler slips a bit and I need to make a second cut. I recommend making a couple of test HSTs before cutting all of your fabric. You may find that you are comfortable starting with smaller squares of fabric.

how to make 8 HSTs at a time:
Tutorial: How to make 8 Half Square Triangle (HSTs) at a time. Magic 8, quilt blocks

After stitching and trimming on the line between the stitches, press seams. I like to press the seams on my HSTs open. Then, square up your HST blocks to your desired size.

 

3. Making HSTs with strips of fabric:

Determine the size you want your unfinished HST block to be (the size before you sew your blocks together, taking in account the ¼” seam allowance). This is the minimum measurement you want to cut the widths of the strips to make your half-square triangles.

formula:

UNFINISHED HST BLOCK = STRIP WIDTH TO MAKE HSTS USING THE STRIP METHOD*

*for unfinished HSTs that are 2½” or smaller, add an extra ¼” to the strip width as indicated in the chart below.

example:
Half Square Triangle formula, making LOTS at a time with the strip piecing method
Half Square Triangle formula, making LOTS of HSTs at a time with the strip piecing method

* When making half-square triangles, I always like to square up my blocks before I use them. I find that this helps make block alignments precise and enables me to have better results when piecing my half-square triangles together. I also make my HSTs with more fabric than some other quilters do. While there is a bit more waste, adding this extra amount makes for a less frustrating trimming experience, especially if my ruler slips a bit and I need to make a second cut. I recommend making a couple of test HSTs before cutting all of your fabric. You may find that you are comfortable starting with smaller squares of fabric.

how to make LOTS of HSTs at a time using the strip method:
Tutorial: How to make LOTS of Half Square Triangle (HSTs) at a time using the strip method.

After stitching and trimming on the line between the stitches, press seams. I like to press the seams on my HSTs open. Then, square up your HST blocks to your desired size.


ARE YOU READY TO MAKE A HALF SQUARE TRIANGLE QUILT?
Here are some project ideas:

Stone Slice: a modern, easy quilt pattern inspired by geodes, rocks and crystals. This is the perfect quilt pattern to make a gift for a budding geologist or stone / crystal lover! Instructions come in 3 sizes: mini, throw and queen and is friendly for the beginner quilter. Comes together with fabric strips and half square triangles (HSTs). Pattern by Whole Circle Studio

 Stone Slice quilt. Get the pattern here!

Leaf Peepers quilt blocks. Easy to piece half square triangle blocks. Make a mini quilt, table runner, wall hanging, twin quilt or queen quilt. Quilt Along with Leah Day and Whole Circle Studio.
Leaf Peepers quilt and runner. Get the pattern here!

Go Fish! This is a fun, modern pattern that is comprised mostly of half square triangles. This tested pattern contains detailed instructions and diagrams, making it a breeze to piece. Works well with prints, solids or a combination of both!
Little Fishies quilt and runner. Get the pattern here!

Make these placemats to spruce up your dining table. Keep them for yourself or make them as a gift (or make two sets: one to keep and one to give)! These placemats, inspired by the classic houndstooth print, are comprised of half square triangles. This tested pattern contains detailed instructions and diagrams, making it easy to piece. Works well with prints, solids or a combination of both.
Shifted Houndstooth placemats. Get the pattern here!

Sun Salutations is the perfect gift for the beach lover or yogi in your life. Make this bright, colorful, modern quilt as a reminder of vacations or trips to the beach. This easy, beginner-friendly pattern is a bright, modern twist on the traditional half square triangle quilt. Sun Salutations is a fully tested pattern that contains detailed instructions and diagrams, making it a breeze to piece.
Sun Salutations quilt. Get the pattern here!


Learn easy ways to make Half Square Triangles (HSTs) and formulas for how to size HST blocks to the measurements you need to make your quilt! Learn easy ways to make Half Square Triangles (HSTs) and formulas for how to size HST blocks to the measurements you need to make your quilt! Learn easy ways to make Half Square Triangles (HSTs) and formulas for how to size HST blocks to the measurements you need to make your quilt! Learn easy ways to make Half Square Triangles (HSTs) and formulas for how to size HST blocks to the measurements you need to make your quilt! Learn easy ways to make Half Square Triangles (HSTs) and formulas for how to size HST blocks to the measurements you need to make your quilt!

 

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2 Comments

  1. I have a question. I love your wonderful different direction and design of your quilting stitches. How do you treat your end threads? Do you actually bury each and every thread in the pattern? Burying threads is not my favorite part of quilting.

    1. Hi Shirley, It depends! If I’m in a rush, I typically choose an edge to edge quilting plan. If it’s a special quilt or I want to do a special quilting plan, I do bury each thread. There are definitely quicker ways to do it, but I actually don’t mind burying threads. I highly recommend quilting it a way that is enjoyable for you. Keep stitching! Sheri

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