How to Piece the Easy Pinwheel Mosaic Quilt Block

Posted by Elaine Huff on

Let's take a look at this variation of a mosaic block that I'm calling Pinwheel Mosaic. With only half square triangles and flying geese, the block goes together quickly. Let's get started!

pinwheel mosaic quilt block

Fabric Requirements for a 12" Finished Pinwheel Mosaic Quilt Block:

  • Light/White: 4 - 4" squares
  • Medium/Light Blue: 2 - 4" squares, and 8 - 3.5" squares
  • Medium/Yellow: 2 - 4" squares
  • Dark/Blue: 4 - 3.5" x 6.5" rectangles

mosaic fabric requirements

Sewing Directions:

Half Square Triangle Units:

Step 1:

Using two of the Light/White 4" squares and the Medium/Light Blue 4" squares, make four Half Square Triangle units. Trim/square up the units to 3.5" square. You can find a tutorial for making a basic Half Square Triangle at

mosaic 1

Step 2:

Repeat Step 1 only substituting the four Medium/Yellow 4" squares for the Medium/Light Blue 4" squares. I also have a tutorial for making multiple Half Square Triangle units at

mosaic 2

Center Pinwheel Unit:

Step 3:

Lay out the Step 2 units as shown in the picture below. 

mosaic 3

Step 4:

Sew the half square triangle units into two rows as shown below.

mosaic 4

Step 5:

Press the seam allowances in opposite directions as shown in the picture below.

mosaic 5

Step 6:

Sew the two rows together and...

mosaic 6

Step 7:

Press the seam allowance. I've used the tweak/twirl/furl method for pressing. This method makes for a flatter block. You can find a better picture of this at

mosaic 7

Flying Geese Units:

Step 8:

Using the four Dark/Blue 3.5" x 6.5" rectangles and the eight Medium/Light Blue 3.5" squares, sew together four Flying Geese units like the ones in the picture below. You can find my method for making a no-trim Flying Geese block at

mosaic 8

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Putting It All Together:

Step 9:

Lay out the Half Square units, the Center Pinwheel unit, and the Flying Geese units as shown in the picture below. From here the block goes together like an uneven Nine Patch block.

mosaic 9 

Step 10:

Sew the units into three rows as shown below.

mosaic 10

Step 11:

Press the seam allowances toward the Flying Geese units.

mosaic 11

Step 12:

Finally sew the three rows together and...

mosaic 12

press the seam allowances away from the center of the block as shown below.

mosaic 12 2


This Pinwheel Mosaic block went together so quick! So satisfying to get a block done quickly. I should have used a darker fabric for the Dark/Blue so that it stands out more never know until you try. The block also makes a wonderful secondary design when sewn into a quilt. Check out the layout options below.

Layout Options:

Here's the standard 4 x 4 layout. Love the diamond shapes that show up!

mosaic quilt 1

Here's the same layout but with a narrow sashing added.

mosaic quilt 2

Here it is in an on-point layout. Looks totally different. However, it could be easier to make two different blocks - one with the pinwheel and one with the square block.

mosaic quilt 3

And here's the on-point layout with sashing and cornerstones. I like this one too.

mosaic quilt 4

hope you've enjoyed this Pinwheel Mosaic quilt block tutorial. If you liked this post and want to see more quilting tutorials like this, simply click here to sign up for my newsletter and also receive a free PDF.

Happy Quilting!


P.S. To figure out yardage for a quilt, check out this post:

P.P.S. To see the block and quilt patterns I have for sale, check out my Etsy shop.

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