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3-Patch Quarter Square Triangles

Technique #4 - 3-Patch Units

3 Patch Quarter Square Triangle tutorial

The 3-patch quarter square triangle quilt block is simply a combination of a quarter and half square triangle unit.

This unit is also a block in its own right. You may know it by one of its other common names:

  • Pigeon in the Coop
  • Waste Not Want Not
  • Shadow Box
  • Rocky Mountain

I prefer to foundation piece it—both for accuracy and speed—I simply find it much easier to trim.

And since there are only 3 patches, paper removal is slick as a whistle!

Do you hate paper piecing? Click here to learn how to make the Double Pinwheel block (which is made solely of 3-patch quarter square triangles) using traditional piecing techniques.

Construction Instructions

3 patch quarter square triangle drawing, 3 fabrics

Block Size: 3"(3-1/2" unfinished)

When you are instructed to press, first press the pieced unit flat to set the seam. Then open the patch, pressing from the front. You may want to reduce or eliminate the use of steam for pressing these paperpieced units. Steam tends to curl the paper.

Take a minute to review our favorite 'secret' technique for perfect pressing. It works even with the paper attached. Now THAT'S sweet!

Step 1: Download the patterns

To open and print the patterns you need the Adobe Reader installed on your computer. You can get Adobe Reader here (a new window will open so you can download it without leaving this page) if you need it.

Click here for our free downloadable pattern for the 3" finished block.

In order to print, open the downloaded file, and select the "Print" option.

Remember, you must set 'page Scaling' to 'None' in your printer's setup menu to ensure these blocks print at the proper size.

Additional downloads:

Step 2: Cut the fabric patches

I prefer to cut generously so that placing the patch into position is virtually foolproof to eliminate ripping, a huge time-waster.

Make a couple of these using the patch sizes below until you are comfortable with the technique. Then, tweak the size if it works better for you. Print a copy of that size pattern, make your notes on it and file it away for future reference.

The dimensions in the chart below are for squares, i.e. for our 3" finished block that means for Patch #1 cut one 4-3/4" x 4-3/4" square and then sub cut it twice on the diagonal.

Finished Block Size
Patch # Fabric Total
2” 2-1/2” 3” 4” Sub Cut
1 A 1 3-3/4” 4-1/4” 4-3/4” 5-3/4” Symbol for a quarter square triangle
2 B or C 1 3-3/4” 4-1/4” 4-3/4” 5-3/4” Symbol for a quarter square triangle
3 C 1 3-3/8” 3-7/8” 4-3/8” 5-3/8” Symbol for a half square triangle
Grid Size 2” 2-1/2” 3” 4” na

These are the cut pieces for a three fabric unit.

Patches needed to make a 3-patch quarter square triangle

*As you can see there are more than enough patches to make a single unit. Rarely will you need just one; frequently you'll need 4 if these are units contained within another block. To have enough patches for 4 units, cut 2 of Patch#3. Easy Peasey!

Step 3: Assemble the 3-patch quarter square triangle

For paperpiecing reduce your stitch length to 1.5, install an open toe applique foot if you have one. If you have problems removing the paper, try a 90/14 needle.

Cut a quarter square triangle pattern from the page you downloaded. Cut just outside the dotted line that marks the unfinished edge of each unit. You will trim to size in the last step.

Use a dab of Elmer's Glue Stick—the one that goes on purple and dries clear—position #1, wrong side of the fabric to the unprinted side of your paper pattern as shown below. Use the dashed placement lines to help position it.

Position Patch 1 using the placement lines

With RST, align the edges of the #2 triangle with #1.

Align the edges of #2 with #1

Sew on the solid line between then. Start your stitching before the line begins and stop after it ends by approximately 1/4".

Stitch on the line, starting before and ending after the sewing line


With RST, align the long bias edge of a #3 with the previously sewn patches.

Align the long bias edge of #3 with the sewn unit #1/#2

Stitch, again starting before and ending after the solid line.


Step 3: Trim to size

For me, this is the step that makes paperpiecing this unit the bees knees!

I find it much faster and more accurate to trim around the outside of the square, as opposed to lining up the 45 degree line of my ruler with the diagonal seam (twice). No contest!

Align the 1/4" mark on your ruler with the solid outside line of the unit and trim. This creates your quarter in seam allowance.

Trim to size with your rotary cutter and ruler

Repeat for the remaining three sides.

Your finished 3-patch quarter square triangle looks like this.

If you make only one, all the patches on the left are leftovers. Since most designs use 3 patch quarter square triangles in groups of four, they won't be wasted.

Designs using the 3 Patch Quarter Square Triangle

Many patchwork designs employ the 3 patch quarter square triangle. Some use two fabrics. Others use three. And in a variation of this unit, some use four.

To reveal the name of the design, position your cursor over the image.

IF we have instructions for that block, the image is 'clickable'. At some point in 2014, all the images below will lead to a tutorial.

2 Fabrics

Click here for instructions to make the Southern Belle quilt block Air Castle quilt block Martha Washington Star quilt block Wild Waves quilt block Click here for instructions to make the Whirlwind quilt block Turnstile quilt block

3 Fabrics

Click here for instructions to make the Card Trick quilt block Click here for instructions to make the Southern Belle quilt block Star and Pinwheels quilt block Click here for instructions to make the Double Star quilt block Click here for instructions to make the Double Pinwheel quilt block Centennial quilt block Telluride Puzzle quilt block Twin Star quilt block Paradox quilt block

Variation on a 3 Patch Quarter Square Triangle

Whirlygig quilt block Wheels quilt block

Ready for More Blocks?

There's plenty more to keep you busy! Just check out our Free Quilt Block Pattern Library to find blocks for your next quilting creation!

Return to the top of this 3-Patch Quarter Square Triangle tutorial

Find more ways to make Quarter Square Triangle units

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