Split Rectangle Quilt Block Units

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Another advanced basic unit is the Split Rectangle quilt block unit. Sometimes this unit is called the Half Rectangle Triangle or HRT. You can find examples of this unit in action in the following quilt block designs:

Crazy Ann Quilt Block

Flutterby Quilt Block

Now, don't be fooled into thinking these units will work just like half square triangle units. They won't. They are an entirely different animal.

For starters, a half square triangle will always have the same height and width. This is not the case with Split Rectangles. They can come in a variety of height to width ratios, as shown below.

Illustration of assorted sizes of Split Rectangle Quilt Block Units
Note the variety of widths and heights in these split rectangle quilt block units.


One important thing to know when making these units is that the diagonal can either go left to right or right to left. Since the two different directions are mirror images of each other, care must be taken when cutting your fabrics to make sure you haven't reversed the unit.

Illustration of pair of mirror image split rectangles
Pair of split rectangles. Note that the diagonal line for the set on the left goes from left to right, while the angle on the other pair goes from right to left.


The formula for making Split Recs is pretty differently from making HST's too. Recall that when making Half square triangles, you will add 7/8" to your finished size, then cut on the diagonal. To make Split Rectangles, first determine the finished size of your rectangle, then add ¼” to the width and ½” to the height.

Here's an example: Suppose I want to make a finished Split Rectangle that measures 3"x 6". Then I would need to cut rectangles that are 3.25" x 6.5", draw a line along the diagonal, then sew seams that are 1/4" away from each side of the drawn line. Once the seams are sewn, cut along the diagonal and press open.

A tool that makes easy work of Split Rectangles is the Split Rects Tool by Studio 180 designs. I've found this tool to give me great results and it really speeds up the cutting process when making these units.


(The link below is an Amazon affiliate link.)

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