Fat quarter size: how big is a fat quarter, and what can you cut from one?

Fat quarter size chart (US and metric)

Why "about"? Quilting cotton is 42 to 44 in (107 to 112 cm) wide before the selvages come off, and each shop squares its cuts a little differently. Plan with a usable 18 x 21 in for a US fat quarter and 50 x 54 cm for a metric fat quarter. Those are the numbers our yield tables use.

A metric fat quarter holds about 8 to 13 percent more fabric than a US one. That matters when a US pattern is "fat quarter friendly": in metric shops you will have a little to spare, which is a lovely position to be in.

Fat eighths are where shops differ most. Most cut the fat quarter in half the long way (US about 9 x 21 to 22 in; metric about 25 x 55 cm), and some halve it the other way, giving a squarer piece of about 50 x 27.5 cm. Check the shop's listing before you plan a fat eighth project around one exact shape.

Fat quarter vs quarter yard: what is the difference?

The fabric is the same amount. The shape is not.

• A quarter yard is 9 in (or 25 cm) cut straight across the bolt: a long, skinny 9 x 42 in strip.
• A fat quarter takes a half yard (18 in, or 50 cm in metric) and cuts it at the centre fold: a chunky 18 x 21 in rectangle.

The fat shape is far more useful for patchwork. A 9 in strip can never give you a 10 in square, or even two rows of 5 in squares. A fat quarter gives you twelve 5 in squares, or two 10 in squares. Long quarters win for one job: long pieces, such as border strips, sashing or a skinny row of binding.

Expert tip: when a pattern calls for "1/4 yd" of a fabric, it usually means a long quarter. When it says "1 fat quarter", it needs the fat shape. Swap them only after checking the cutting list.

What can you cut from a fat quarter?

These yields assume a usable 18 x 21 in (US) or 50 x 54 cm (metric) and straight cuts, checking both directions.

US fat quarter (usable 18 x 21 in)

Metric fat quarter (usable 50 x 54 cm)

The rule behind every number: pieces = (whole pieces across) x (whole pieces down), tried both ways round. For 5 in squares: 18 / 5 = 3 across, 21 / 5 = 4 down, 3 x 4 = 12.

Two things jump out. First, 6 1/2 in squares are greedy: they fit only twice across 18 in and leave a 5 in strip behind, so you get 6. Cut 6 in squares instead and you get 9. Second, the slightly larger metric fat quarter shines at 16.5 cm squares, fitting nine where a US fat quarter fits only six 6 1/2 in squares of the same size.

Strips are friendly too. A US fat quarter cut the long way gives seven 2 1/2 x 21 in strips, about 132 in of binding after the diagonal joins, enough for a 30 in square mini quilt. A metric fat quarter gives seven 6.5 x 54 cm strips, about 339 cm after joins, enough for a 75 cm square mini quilt. For full size binding, see how much binding for a quilt.

How many fat quarters do I need for a quilt?

Four steps, and the math is kind.

1. Pick the quilt size and the cut size of your squares or units. Our quilt sizes guide gives sizes for every bed.
2. Count the pieces: across x down.
3. Divide by the yield per fat quarter from the table above and round up.
4. Add one or two for variety and for the cut that goes wrong. Every quilter has one.

Worked example in inches: a 60 x 72 in throw

Ten 6 in finished squares across and twelve down make a 60 x 72 in throw: 120 squares, cut 6 1/2 in.

• A US fat quarter gives 6 squares at 6 1/2 in.
• 120 / 6 = 20 fat quarters.

Now the expert move. Shrink the square to 5 1/2 in finished (cut 6 in) and the same 10 x 12 layout finishes at 55 x 66 in, still a cosy throw. Each fat quarter now gives 9 squares: 120 / 9 = 13.3, so 14 fat quarters. Six fewer fat quarters for 5 in less width. Size your block to your precut and your budget thanks you.

For comparison, the same 120 squares at 6 1/2 in from yardage: 6 squares per 40 in usable strip, 20 strips, 20 x 6 1/2 = 130 in, plus 3 in for straightening = 133 in. Buy 3 3/4 yd (135 in). Twenty fat quarters are 5 yd of fabric, so you pay a little for variety. It is usually worth it.

Worked example in centimetres: a 150 x 180 cm throw

Ten 15 cm finished squares across and twelve down: 120 squares, cut 16.5 cm (15 cm + 1.5 cm).

• A metric fat quarter (50 x 54 cm usable) gives 3 x 3 = 9 squares.
• 120 / 9 = 13.3, so 14 fat quarters.

From yardage: 6 squares per 102 cm usable strip, 20 strips, 20 x 16.5 = 330 cm, plus 5 cm = 335 cm. Buy 3.4 m. Fourteen metric fat quarters are 3.5 m of fabric, almost identical. In metric, a fat quarter quilt costs you very little extra fabric.

Fat quarters cover the top. Plan the backing, batting and binding separately; how to make a quilt walks through the whole order.

Precut sizes chart: charm pack, layer cake, jelly roll and more

Precuts are prepared fabric pieces sold in bundles, usually one or two of every print in a collection. The sizes below are the standard cuts; counts vary by maker and line.

The equivalents are fabric area, so they tell you how much fabric is in the bundle, not how much yardage you would buy to cut the same pieces (cutting always leaves a little behind). Turnovers vary most between collections; some lines use 5 in squares, so check the listing for the size and count.

What each precut does best:

• Charm pack: 42 squares make a 6 x 7 grid of 4 1/2 in finished squares, a 27 x 31 1/2 in baby or mini quilt. Pairs make 2 at a time HSTs that trim to 4 in finished; see the half square triangle chart.
• Layer cake: 42 squares sewn as plain squares (9 1/2 in finished) make a 57 x 66 1/2 in throw in a 6 x 7 layout. Pairs sewn 8 at a time give eight HSTs that trim to 4 in finished.
• Jelly roll: strip quilts, log cabin, rail fence and scrappy binding. A classic jelly roll race quilt finishes around 50 x 64 in.
• Honey bun: skinny logs (1 in finished), sashing and string quilts.
• Dessert roll: 5 in strips, eight 5 in squares per strip.

Precut brand names

Charm Pack, Layer Cake, Jelly Roll, Honey Bun, Dessert Roll and Turnover are Moda Fabrics product names (Moda also calls its mini charm packs Candy). Other makers sell the same cuts under their own names:

Other makers have their own names too. When a pattern names a brand, think of the generic size and any maker's bundle will work, as long as the count is enough.

How do you measure a precut with pinked edges?

Most precuts are cut with pinking blades so the edges fray less. Measure from the outer points of the zigzag, not the valleys. Most patterns written for precuts set the 1/4 in seam from those points. If you measure from the valleys, your charm square suddenly looks 1/8 in short and you start trimming fabric that was perfect all along.

Should you prewash fat quarters and precuts?

Skip it for precuts. Small pieces fray, shrink unevenly and twist out of square in the wash, and a 2 1/2 in strip can lose a real share of its width. Sew them as they come and add a colour catcher sheet to the first wash of the finished quilt.

Fat quarters are a judgement call. Most quilters skip prewashing them too. If a fat quarter is a deep red, indigo, batik or hand dye that you plan to sit beside white, test a snippet for colour bleeding first. If you do wash one, wash all the fabrics in the project, and expect to lose a little size, since cotton can shrink a few percent.

Fat quarters for sewing, not only quilts

Fat quarters are a gift to garment and accessory sewists too. One fat quarter covers a zip pouch with lining, a few scrunchies, a pair of pocket linings or a tidy run of bias binding for a neckline. Bundles are an easy way to get coordinated prints for small makes without buying a half yard of each.

Fat quarter mistakes and fixes

• Planning with 18 x 22 in. After selvages and squaring, assume 18 x 21 in. Plan with 22 in and the last row of squares comes up short.
• Buying a long quarter for a fat quarter pattern. Same area, wrong shape. A 9 in strip will not give 10 in squares.
• Following a US yield in a metric shop (or the reverse). A metric fat quarter is larger, so US counts are safe, and metric counts can be too generous for a US piece.
• Choosing a cut size that wastes a strip. 6 1/2 in squares leave 5 in unused across a US fat quarter. Check the yield table and adjust the block size where you can.
• Measuring pinked edges from the valleys. Measure from the outer points.
• Assuming every bundle has 42 pieces. Charm packs range from 30 to 42 squares by brand. Count before you cut.
• Prewashing precuts. Keep them as they come.