Pinwheels & triangles · Intermediate

Double X No. 3 quilt block

A dark center four patch on a light ground, with three half-square triangles in each corner pointing toward the center.

Double X No. 3: main and background. A 6 × 6 grid.

Cutting chart by block size

Fabric	Cut	Size	Then
Main	6 squares	1 7/8" × 1 7/8"	12 triangles (cut once on the diagonal)
Main	4 squares	1 1/2" × 1 1/2"	–
Background	6 squares	1 7/8" × 1 7/8"	12 triangles (cut once on the diagonal)
Background	20 squares	1 1/2" × 1 1/2"	–

Fabric	Cut	Size	Then
Main	6 squares	2 3/8" × 2 3/8"	12 triangles (cut once on the diagonal)
Main	4 squares	2" × 2"	–
Background	6 squares	2 3/8" × 2 3/8"	12 triangles (cut once on the diagonal)
Background	20 squares	2" × 2"	–

Fabric	Cut	Size	Then
Main	6 squares	2 7/8" × 2 7/8"	12 triangles (cut once on the diagonal)
Main	4 squares	2 1/2" × 2 1/2"	–
Background	6 squares	2 7/8" × 2 7/8"	12 triangles (cut once on the diagonal)
Background	20 squares	2 1/2" × 2 1/2"	–

Fabric	Cut	Size	Then
Main	6 squares	3 3/8" × 3 3/8"	12 triangles (cut once on the diagonal)
Main	4 squares	3" × 3"	–
Background	6 squares	3 3/8" × 3 3/8"	12 triangles (cut once on the diagonal)
Background	20 squares	3" × 3"	–

Cut the pieces in the chart above. All measurements include a 1/4" seam allowance.
Cut the squares marked "cut once" in half on the diagonal. Each gives two triangles. Sew them to their neighbours along the long edge first and press toward the darker fabric.
Lay all the pieces out as in the diagram. The block is a 6 × 6 grid, and each cell finishes at 2 1/2". Sew neighbouring pieces into sections, then the sections into rows, pressing seams in opposite directions from row to row.
Join the rows. The block should measure 15 1/2" now and 15" once it is sewn into the quilt.

Yardage for a Double X No. 3 quilt (15" blocks)

Quilt size	Blocks	Finished size	Main	Background	Border & binding	Backing
Baby	2 × 3 (6)	36" × 51"	1/2 yd	1 1/4 yd	1 yd	3 1/2 yd
Lap	3 × 4 (12)	51" × 66"	1 yd	2 3/8 yd	1 1/8 yd	4 1/4 yd
Throw	4 × 4 (16)	66" × 66"	1 3/8 yd	3 yd	1 3/8 yd	4 1/4 yd
Twin	4 × 6 (24)	66" × 96"	2 yd	4 1/2 yd	1 1/2 yd	6 yd
Queen	6 × 6 (36)	96" × 96"	2 7/8 yd	6 5/8 yd	1 7/8 yd	8 3/4 yd
King	7 × 7 (49)	111" × 111"	3 7/8 yd	9 yd	2 1/8 yd	10 yd

Blocks side by side with a 3" border, 2 1/2" binding, 42" usable width and 10% extra.

A throw quilt of 15" Double X No. 3 blocks in each setting.

Setting	Blocks	Finished size	Extra fabric
Side by side	16	66" × 66"	–
With sashing	12	55" × 72"	Sashing 3/4 yd, Cornerstones 1/8 yd
Alternating plain blocks	8 pieced + 8 plain	66" × 66"	Plain blocks 2 yd
On point	13	69 3/4" × 69 3/4"	Setting triangles 1 3/4 yd

1. Your fabrics (tap a fabric, then choose a sample or your own photo)

2. Block

3. Quilt size

4. Block size

5. Setting

Border

Fabric	Yardage	Cut

Based on 42" usable fabric width, 1/4" seams and 10% extra. Your photos stay on your device.

How many fabrics does a Double X No. 3 block need?

Two: main and background. Choose a main fabric that contrasts clearly with the background so the design reads from a distance.

What size pieces do I cut for a 15 inch Double X No. 3?

6 main squares at 3 3/8" × 3 3/8"; 4 main squares at 3" × 3"; 6 background squares at 3 3/8" × 3 3/8"; 20 background squares at 3" × 3".

How many Double X No. 3 blocks for a lap quilt?

12 blocks at 15", set 3 by 4 with a 3" border, make a 51" × 66" quilt.

The app is in the works. Join the early list and help decide what goes in.