Pinwheel Quilt Block — Cutting Chart by Finished Size

2 fabrics · Difficulty 2 of 5

Pinwheel is a 2×2 block of 8 pieces. Cut sizes for 4″, 8″, 12″, 16″, 20″ are below; for any other size it divides into cleanly, type the size and the chart recomputes.

Accepted finished sizes must resolve to ruler-compatible cuts; unsupported sizes are refused with nearby clean sizes and are never silently rounded.

At a glance

Grid

2×2

Pieces you cut

4 — subcutting turns them into the 8 in the sewn block

Difficulty

2 of 5 — easy · How this is scored

Which sizes divide cleanly

Scroll sideways to see every column.

• A 5-patch block at 12″ would need 2.4″ units, which is not a mark on any ruler. Try 10″ or 12½″ instead — Sister's Choice is the 5-patch block on this site.
• A 7-patch block at 12″ would need 1.714…″ units, which is not a mark on any ruler. Try 10½″ or 14″ instead — Bear's Paw is the 7-patch block on this site.

More about the sizes that do not divide cleanly

The sizes in between

Every whole-inch Pinwheel size from 4″ to 20″ can be cut accurately on its 2×2 grid.

These sizes divide cleanly but sit between the main chart's columns — the same computed cuts, published here so they exist on paper too. Any other clean size still computes in the size input above.

Column headings are the FINISHED block size — the size it will be once it is sewn. Every number in the table is the size to CUT, which includes ¼″ of seam allowance on each edge. Rows that are subcut on a diagonal are cut larger still, so the allowance survives the extra cuts.

Scroll sideways to see every size.

About this block

Pieces in the finished block

8

Unit types

half-square-triangle unit

Divides cleanly at

1″, 2″, 3″, 4″, 5″, 6″, 7″, 8″, 9″, 10″, 11″, 12″, 13″, 14″, 15″, 16″, 17″, 18″, 19″, 20″ and 21″ finished.

Also known as

Windmill, Water Wheel, Fan Mill, Crow's Foot, Mosaic No. 9

Attribution

Ohio Farmer, 1898 (as Windmill)

Fabric for one 12″ block

This is a conservative buying estimate for one cut size at a time: ½ yd total, assuming 40″ of usable width of fabric; different cut sizes are not co-packed, and purchase length is rounded up to the next eighth yard.

The triangle units turn in sequence, and their feature-fabric halves make the pinwheel turn around the centre. Lay out all units before sewing so the turn stays consistent; at the middle crossing, match the diagonal points and press the last seam open to reduce bulk.

Piecing order

1. Make the 4 half-square-triangle units.

2. Lay out row 1 of 2 and sew its pieces together, left to right.

3. Lay out row 2 of 2 and sew its pieces together, left to right.

4. Join the 2 rows, matching the seams.

Cutting oversize

The chart gives the standard cut sizes, nothing padded. Some quilters cut this block's triangle units a little oversize and trim back — published allowances genuinely disagree on how much, so the range with its sources is on how to square up a quilt block.

History

Few blocks have collected more names: the recorded list runs from Windmill and Water Wheel to Fly, Crow's Foot and Kathy's Ramble, and the Ladies Art Company filed it as Mosaic No. 9 in their numbered mosaic series. The Ohio Farmer printed it as Windmill in 1898. Two fabrics and four half-square triangles make the whole design; every name is something someone saw in the turning.

Sources: Generations Quilt Patterns — Pinwheel.

Common questions