Quilt math · Precuts
Fat quarter and fat eighth sizes
What a fat quarter, a fat eighth and a quarter yard measure, how they differ, and how many squares each one gives.
The short answer
A fat quarter is 18″ × half the width of the fabric: 18″ × 21″ once the selvages are off, often sold as 18″ × 22″. A fat eighth is 9″ × 21″. A quarter yard from the bolt is the same fabric as a fat quarter, but 9″ × 42″.
Fat quarter, fat eighth and quarter yard sizes
A fat quarter is a half yard cut in half across the width: 18″ by half the width of the fabric. A fat eighth is a fat quarter cut in half again, 9″ by half the width. A quarter yard from the bolt (a “long quarter”) is the same amount of fabric as a fat quarter, but long and thin.
Quilting cotton is usually 42–44″ wide on the bolt. Take off the selvages and about 42″ is left to cut, so this page and Quarter Inch plan with a fat quarter of 18″ × 21″.
| Piece | Size | Area |
|---|---|---|
| Fat quarter | 18″ × 21″ | 378 sq in |
| Fat eighth | 9″ × 21″ | 189 sq in |
| Quarter yard (long quarter) | 9″ × 42″ | 378 sq in |
| Half yard | 18″ × 42″ | 756 sq in |
When your fabric is wider or narrower
A fat quarter is half the usable width, so it changes with your fabric:
| Width, selvages off | Fat quarter | Fat eighth |
|---|---|---|
| 40″ | 18″ × 20″ | 9″ × 20″ |
| 42″ | 18″ × 21″ | 9″ × 21″ |
| 44″ | 18″ × 22″ | 9″ × 22″ |
That inch matters more than it looks. From a 18″ × 21″ fat quarter you cut 30 squares of 3½″; from 18″ × 20″ only 25. Measure yours before you plan to the last square. A 18″ × 22″ fat quarter is what a pack’s “18″ × 22″” usually means: the full width before the selvages come off.
What you can cut from one
Cut strips along the fat quarter’s length, side by side, then cut squares from each strip. These are whole squares from one piece at 42″ wide, as Quarter Inch lays them:
| Square, cut | Sews to | Fat quarter | Fat eighth | Quarter yard |
|---|---|---|---|---|
| 2½″ | 2″ | 56 | 24 | 48 |
| 3½″ | 3″ | 30 | 12 | 24 |
| 4½″ | 4″ | 16 | 8 | 18 |
| 5″ | 4½″ | 12 | 4 | 8 |
| 6½″ | 6″ | 6 | 3 | 6 |
| 10″ | 9½″ | 2 | — | — |
Same fabric, different shape. A fat quarter and a quarter yard hold the same 378 square inches. For small squares they give about the same; for anything over 9″, only the fat quarter will do.
Fat quarter bundles
A bundle is one fat quarter of each print in a collection, or a chosen few. How many are in one depends on the collection: there’s no standard count, so read the label. Fat eighth bundles are the same idea at half the size.
To work out how many you need for a quilt, see how many fat quarters for a quilt. For the other precuts, see charm packs, layer cakes and jelly rolls.
Fat quarters in Quarter Inch
In a quilt’s yardage, Quarter Inch says when a fabric fits in one fat quarter. Starting a quilt from fat quarters you have? On New quilt, open More ways to start and choose From a precut you have: it works out which pieces each fat quarter gives, block by block.
Questions
Short answers.
Something else? A real person replies.
hello@quarterinch.app
How big is a fat quarter?
18″ by half the width of the fabric: 18″ × 21″ once the selvages are off, or about 18″ × 22″ as it’s cut from the bolt.
Is a fat quarter the same as a quarter yard?
It’s the same amount of fabric, 378 square inches, in a different shape. A quarter yard is 9″ × 42″; a fat quarter is squarer, so bigger pieces fit.
How big is a fat eighth?
Half a fat quarter: 9″ × 21″.
How many 5″ squares are in a fat quarter?
12, from a 18″ × 21″ fat quarter: strips of 5″ side by side, then squares from each strip.
How many fat quarters are in a yard?
Four. Cut a yard in half across the width, then cut each half yard in half along the fold.
Sources
We checked every fact above against these pages on , and we update this guide when they change. Spotted something out of date? Write to hello@quarterinch.app.
- Moda pre-cut fabric: a complete guide The Sewing Studio