Pinwheel quilt block
Four half-square triangles rotated around a common centre so the darks spiral. Four pieces, one seam intersection, and a block that never stops being useful.
Also known as Water Wheel, Windmill.
The pinwheel is what happens the first time somebody rotates four identical HSTs instead of mirroring them. It appears constantly in nineteenth-century scrap quilts because it makes a strong graphic from two fabrics and almost no cutting, and it survives into modern quilting for exactly the same reason.
Pinwheel cutting chart
Cut sizes include a ¼″ seam allowance: ½″ on squares and rectangles, ⅞″ on half-square triangles, and 1¼″ on quarter-square triangles. Pick a finished block size:
| Fabric | Shape | Cut size | Qty | Notes |
|---|---|---|---|---|
| Background | HST square | 3⅞" × 3⅞" | 2 | cut once on the diagonal → 4 triangles |
| Dark | HST square | 3⅞" × 3⅞" | 2 | cut once on the diagonal → 4 triangles |
| Fabric | Shape | Cut size | Qty | Notes |
|---|---|---|---|---|
| Background | HST square | 5⅜" × 5⅜" | 2 | cut once on the diagonal → 4 triangles |
| Dark | HST square | 5⅜" × 5⅜" | 2 | cut once on the diagonal → 4 triangles |
| Fabric | Shape | Cut size | Qty | Notes |
|---|---|---|---|---|
| Background | HST square | 5⅞" × 5⅞" | 2 | cut once on the diagonal → 4 triangles |
| Dark | HST square | 5⅞" × 5⅞" | 2 | cut once on the diagonal → 4 triangles |
| Fabric | Shape | Cut size | Qty | Notes |
|---|---|---|---|---|
| Background | HST square | 6⅞" × 6⅞" | 2 | cut once on the diagonal → 4 triangles |
| Dark | HST square | 6⅞" × 6⅞" | 2 | cut once on the diagonal → 4 triangles |
| Fabric | Shape | Cut size | Qty | Notes |
|---|---|---|---|---|
| Background | HST square | 8⅜" × 8⅜" | 2 | cut once on the diagonal → 4 triangles |
| Dark | HST square | 8⅜" × 8⅜" | 2 | cut once on the diagonal → 4 triangles |
How it goes together
Make four identical HSTs, then rotate each a quarter turn as you lay them out so all four darks chase each other around the centre. The eight seam allowances meeting at the middle are the challenge.
Tips
- Press the centre seam open, or spin it — press the final seam so the allowances swirl in a circle and the centre lies flat instead of building into a knot.
- All four triangles must rotate the same way. Mirror one and you get Broken Dishes instead.
- Two fabrics is plenty. The block is about motion, and extra colours fight the spiral.
How much fabric for a Pinwheel quilt?
Yardage for a whole quilt of Pinwheel blocks, computed the way the studio does it — every piece packed across a 40″ usable width with 10% added for waste.
| Quilt size | Blocks | Finished | Top fabric | Backing | Binding |
|---|---|---|---|---|---|
| Baby 36×48 | 12 | 36" × 48" | Background 1⅛ yd · Dark 1⅛ yd | 2½ yd | ⅜ yd |
| Throw 60×72 | 30 | 60" × 72" | Background 2⅝ yd · Dark 2⅝ yd | 3⅞ yd | ½ yd |
| Queen 90×108 | 72 | 96" × 108" | Background 6⅛ yd · Dark 6⅛ yd | 8¾ yd | ⅞ yd |
What it looks like in a quilt
A single block only tells you half the story. Set sixteen of them together and the secondary pattern appears where the blocks touch:
Pinwheel questions
Why is the centre of my pinwheel so bulky?
Eight seam allowances converge there. Spinning the seams — clipping the last few stitches of the centre seam so the allowances can fan in a circle — removes the lump entirely.
What size squares make a 12 inch pinwheel?
Each HST finishes at 6 inches, so cut two squares at 6⅞ inches and cut each once on the diagonal.