Block Library

Pinwheel

A classic quilt block made from four half-square triangle units arranged to create spinning motion. A favorite for beginner quilts, baby quilts, and traditional patchwork.

BeginnerTraditionalHalf-Square TrianglesRotation

Why quilters love the Pinwheel

Strong movement and visual energy
Great use of contrast fabrics
Excellent introduction to HST piecing
Looks traditional or modern depending on fabric
Repeats beautifully across an entire quilt

Construction at a glance

What you'll work with

Half-square triangles (HSTs)
Straight seams
Bias edges inside units
No templates required
Best when trimmed accurately

Common finished sizes

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Cutting guide

For an 8" Finished Block

2 Fabric A (light) squares at 5"
2 Fabric B (dark) squares at 5"

These create 4 HST units. Cut oversized and trim each to exactly 4½" unfinished.

Tip: Cutting at 5" gives you room to trim precisely. Accurate trimming is the single biggest factor in a flat, well-matched block.

Sizing formula: Finished block size ÷ 2 = unfinished unit size
Then use HST sizing method.

8" block = 4.5" unfinished HSTs
12" block = 6.5" unfinished HSTs
16" block = 8.5" unfinished HSTs

How to sew the Pinwheel

1
On the wrong side of each Fabric A square, draw a diagonal line from corner to corner.
2
Place one Fabric A square on one Fabric B square, right sides together.
3
Sew ¼" to the left of the drawn line, then ¼" to the right. Repeat with the second pair.
4
Cut along the drawn diagonal line between the two seams.
5
Open each unit and press the seam toward Fabric B (the darker fabric).
6
Trim each HST to exactly 4½" x 4½", aligning the 45° ruler line with the diagonal seam.
7
Arrange the four HSTs in a 2x2 grid so the dark triangles all point toward the center in the same rotation direction.
8
Sew the top two HSTs together; press the seam toward the right. Sew the bottom two; press toward the left.
9
Join the two rows, nesting the center seams. Press the final center seam open to reduce bulk.

Accuracy tips

Cut starting squares at 5" and trim HSTs down to 4½" — oversizing then trimming is more accurate than cutting to exact size
Use a consistent ¼" seam; try a scant ¼" (a thread width less) if your finished block runs small
Press straight down — dragging the iron stretches bias edges
Align the 45° line on your ruler to the diagonal seam when trimming each HST
Confirm all four HSTs are oriented correctly before sewing — lay them out and check the spin direction

Common mistakes

Center Point Doesn't Meet: Inconsistent ¼" seams or HSTs not trimmed to identical sizes.
HSTs Are Different Sizes: Starting squares varied slightly or trimming was rushed — re-trim any outliers before assembly.
Block Smaller Than 8½" Unfinished: Seam allowance is running wide. Try a scant ¼", about a thread's width less than a true ¼".
Fabric Stretching on Diagonal Edges: HST edges are cut on the bias. Handle units gently, press rather than drag, and use starch on starting squares.

Fabric ideas

High contrast solids
Navy + cream classics
Scrappy prints
Seasonal colors
Two-tone modern palettes

Variations

Double Pinwheel
Broken Pinwheel
Pinwheel Star
Mini Pinwheel border blocks

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Browse all 9 classic quilt blocks with cutting guides and assembly instructions.

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