Birds in the Air Quilt Block Pattern

New to quilting? Check out our beginner quilting class covering all the basics.

How to Sew a Birds in the Air Quilt Block

The Birds in the Air quilt block is a classic design that uses half-square triangles in two fabrics — a bird fabric and a background fabric — arranged to suggest birds soaring in flight.

Materials Needed

• Fabric in your desired colors (bird fabric and background fabric)
• Sewing machine and thread
• Rotary cutter and cutting mat
• Ruler
• Iron and ironing board
• Pins

Cutting Guide

• Background fabric: one 4½" square and four 2½" squares
• Bird fabric: two 4½" squares and four 2½" squares

Step 1: Create the Half-Square Triangles (HSTs)

1. Pair each 4½" background square with a 4½" bird fabric square, right sides together.
2. Draw a diagonal line on the wrong side of each background square.
3. Sew a ¼" seam allowance on both sides of the diagonal line.
4. Cut along the diagonal line and press the HSTs open with the seam allowance toward the bird fabric.

Step 2: Assemble the Block

1. Take two HSTs and pair them right sides together — one with background fabric facing up, one with bird fabric facing up. Make sure the seams are nesting.
2. Sew a ¼" seam allowance on both sides of the center diagonal. Cut along the center diagonal line and press the seams open.
3. Repeat with the other two HSTs to create the second half of the block.
4. Join the two halves together by sewing a ¼" seam allowance along the center diagonal, making sure the seams are nesting. Cut away any excess fabric and press the final seam open.

Step 3: Trim the Block

Using a ruler, trim the block to 4½" square, centering the diagonal seam in the middle of the block.

Your Birds in the Air quilt block is complete! Repeat these steps to create more blocks, then join them together to form your quilt top.

Half-Square Triangle (HST) Technique

This technique eliminates the need to directly manipulate the stretchy bias of the triangle. It uses two easy-to-cut squares and produces two HSTs at once.

Step 1: Draw the Diagonal Line

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

Step 2: Sew Both Sides of the Line

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:

Step 3: Cut, Press, and Trim

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

Line up the 45° diagonal angle on your ruler with the seam, then carefully trim with a rotary cutter.

Corner Square Technique

Use this technique to add precise corner triangles to any block unit.

Step 1: Sew the Squares Together

Step 2: Mark the Diagonal Line

Mark the wrong side of the unit with a pencil line, aligning the corners of the squares and the intersection of the seams.

Step 3: Align and Sew the Corner

Line up the corner of the square or triangle you will add to the corner of the unit.

Sew a seam one thread's width from the marked line — this tiny allowance makes room for the fold of the fabric so the triangle point isn't cut off. Fold the triangle into position using the squares to assist alignment, then press.

Step 4: Trim

Trim away excess fabric to reduce bulk, leaving a ¼" seam allowance and trimming the ears.

How to Resize Quilt Blocks

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

Note: When working from a pattern's cutting instructions, remove the seam allowance before scaling. For example, if your pattern calls for 3½″ squares, subtract the seam allowance (½″), double the finished size (3″ → 6″), then add the seam allowance back (½″) — giving you a 6½″ cut piece.

Resizing Square Blocks

Add ½″ to your 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 3″ × 4″ block, cut a 6½″ × 8½″ rectangle.

Resizing Half-Square Triangle Blocks

Add 7/8″ to the desired finished block size. For a 4″ finished HST block, cut 4⅞″ squares.

Resizing Quarter Square Triangle Blocks

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