Whirlwind Quilt Block Pattern

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How to Sew a Whirlwind Quilt Block

The Whirlwind quilt block creates a beautiful swirling effect in any quilt design. Here’s what you’ll need and how to make it.

Materials:

• Fabric in two or more contrasting colors
• Sewing machine & thread
• Rotary cutter, cutting mat & ruler
• Iron

Instructions:

1. Choose two contrasting fabrics for your block.
2. Cut two squares of each color. The size depends on your desired finished block — for a 12" block, cut four 6" squares.
3. Place one square of each color right sides together and pin if desired.
4. Sew a ¼" seam around all four sides of the squares.
5. Cut the sewn squares in half diagonally from corner to corner to create four triangles. Press seams open.
6. Take two triangles (one of each color) and place them right sides together, matching the seams. Sew a ¼" seam along the long edge, starting at the tip and ending at the opposite end. Repeat with the remaining two triangles. Press seams open.
7. Place the two triangle pairs right sides together with opposite colors touching. Sew a ¼" seam along the long edge. Press seams open.
8. Trim the block to your desired finished size, squaring it up carefully.
9. Repeat to create as many Whirlwind blocks as needed for your quilt.

Making Half-Square Triangles

This technique eliminates the need to directly manipulate the stretchy bias of the triangle. It uses two easy-to-cut squares to produce two half-square triangles.

On the back of the lighter fabric, draw a pencil line diagonally from corner to corner.

Stack a pair of light and dark squares right sides together. Sew a ¼" seam allowance on each side of the line.

You will end up with something like this:

Now cut along the diagonal line.

Press the seam to set it, then press toward the darkest fabric.

To trim to the exact size, line up the 45° diagonal on your ruler with the seam.

Then carefully trim your block with a rotary cutter.

How to Resize Quilt Blocks

The first step in modifying any quilt block is to decide on the finished size. You can base this on doubling a pattern, cutting it in half, or working with your available fabric.

Important: Always remove the seam allowance before doubling or tripling the size. For example, if your pattern calls for 3½" squares, subtract the seam allowances (½"), double the finished block size (3" → 6"), then add the seam allowance back (½"). You’ll end up cutting a 6½" piece of fabric.

Resizing Square Blocks

Add ½" to your desired finished block measurement. For a 4" finished square, cut a 4½" square of fabric.

Resizing Rectangular Blocks

Add ½" to both the length and width. To double a block that measures 3" × 4", cut a 6½" × 8½" rectangle of fabric.

Resizing Half-Square Triangle Blocks

Add ⅞" to the desired finished block size. For a 4" finished block, cut 4⅞" squares.

Resizing Quarter-Square Triangle Blocks

Add 1¼" to the desired finished block size. For a 4" finished block, cut your squares 5¼".