Oh Susannah Quilt Block Pattern

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How to Sew the Oh Susannah Quilt Block

The Oh Susannah quilt block is a traditional design made up of nine squares arranged in a specific pattern using half-square triangles.

Materials:

• Fabric in 3 different colors or patterns
• Sewing machine & scissors
• Iron and ironing board
• Rotary cutter, cutting mat & ruler

Cut your fabric:

• 4 squares of Fabric A: 4⅞"
• 4 squares of Fabric B: 4⅞"
• 1 square of Fabric C: 4½"

Instructions:

1. Pair each Fabric A square with a Fabric B square, right sides facing each other.
2. Draw a diagonal line on the wrong side of each Fabric A square using a pencil or fabric marker.
3. Sew a ¼" seam on both sides of the diagonal line.
4. Cut along the diagonal line to create two half-square triangle (HST) units from each pair.
5. Press the seams toward the darker fabric.
6. Trim each HST unit to 4½" using a ruler and rotary cutter.
7. Lay out the 9 squares in the following pattern:
   • Row 1: HST (A/B) — Fabric A square — HST (B/A)
   • Row 2: HST (B/A) — Fabric C square — HST (B/A)
   • Row 3: HST (A/B) — Fabric A square — HST (B/A)
8. Sew the squares into three rows, pressing seams in opposite directions on each row.
9. Sew the rows together, matching seams and pressing the seam allowance in one direction.
10. Trim the finished block to 12½".

Your Oh Susannah quilt block is complete! Repeat to create as many blocks as needed for your quilt project.

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: When working from a pattern's cutting instructions, 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".