Quilting guide

How to piece a quilt back: seams, overage and wide backing

Updated October 5, 2026 by Khokhar Sab

Add 4 inches to every side of the quilt top. Then work out how many widths of fabric cover that, allowing for the selvages and the seams that join them. A 90 by 95 inch queen quilt needs a 98 by 103 inch backing, which takes 8¼ yards of 42 inch fabric with horizontal seams.

Why the backing is bigger than the top

Cut the backing larger than the quilt top on every side. Quilters call this extra overage. The calculator uses 4 inches per side by default, so the backing is 8 inches wider and 8 inches longer than the top.

There are two reasons for it. Quilting draws the layers in a little and they can shift while you work, so a backing cut to the exact size can end up short at an edge. And if the quilt goes on a longarm frame, the quilter pins or clamps the backing edges to the frame. That uses up fabric that never ends up inside the quilt. For longarm quilting the calculator's notes suggest 4 to 6 inches per side, and a longarm quilter may have a set amount they want, so ask before you buy. Quilted Joy's backing guide, for example, asks for 4 inches beyond the quilt on all four sides for longarm quilting.

For the queen size, 90 + 2 × 4 = 98 inches wide, and 95 + 2 × 4 = 103 inches long.

Usable width and seam allowance

Standard quilting cotton comes about 42 inches wide, but you can't use all of it. Trim off the selvages, the tightly woven edges, before seaming because they can pucker a seam. The calculator takes 2 inches off in total, which leaves 42 − 2 = 40 usable inches.

When you sew two panels together, each seam uses up some width. With a ½ inch seam allowance on each piece, every seam takes 1 inch from the total. So:

• One panel covers 40 inches.
• Two panels cover 2 × 40 − 1 = 79 inches.
• Three panels cover 3 × 40 − 2 × 1 = 118 inches.

The default ½ inch is wider than the ¼ inch seam used to piece a quilt top. If you sew backing seams at a different width, change it in the calculator and the panel count updates.

Vertical or horizontal seams

With vertical seams, the panels run the length of the quilt and sit side by side across its width. With horizontal seams, the panels run across the width and stack down the length. You cut each panel to the full length of the side it runs along, so the two layouts can need quite different amounts of fabric.

Here is the queen example worked both ways, with 40 inch usable fabric:

• Vertical: 98 inches of width needs 3 panels, each 103 inches long. 3 × 103 = 309 inches, or 8⅝ yards after rounding up.
• Horizontal: 103 inches of length needs 3 panels, each 98 inches long. 3 × 98 = 294 inches, or 8¼ yards.

Horizontal seams save ⅜ yard here, so the calculator recommends them. If your backing fabric has a one-way print, though, horizontal panels would turn the print sideways. In that case use vertical seams and buy the larger amount. The calculator has a setting for directional prints that does this.

The calculator rounds yardage up to the next ⅛ yard (4½ inches), the usual cutting step in US fabric shops.

The 60 inch rule of thumb, checked

Craftsy's backing guide gives a quick rule: horizontal seams for quilts 40 to 60 inches wide, and vertical seams for quilts 61 inches or wider. Here is the rule next to the calculator's yardage both ways, at the default settings.

The rule picks the cheaper layout for the throw, twin and king, but it misses on the full and queen. Following it there costs ½ yard on the full and ⅜ yard on the queen. Both of those quilts need three panels either way, and you cut horizontal panels to the backing width, which is the shorter side. So work out both layouts for your own quilt rather than going by width alone.

Working it out by hand

1. Measure the finished quilt top and add twice the overage to each side.
2. Subtract the selvage trim from the fabric width to get the usable width.
3. For vertical seams, find how many panels cover the backing width, remembering that each seam uses 1 inch. Multiply the panel count by the backing length.
4. For horizontal seams, do the same with the backing length, and multiply by the backing width.
5. Divide each total by 36 to get yards, round up to the next ⅛ yard, and pick the smaller one unless the print is directional.

If the backing only just needs an extra panel, it can be worth checking whether a slightly smaller overage would save a whole width of fabric. Ask your longarm quilter first, since their frame sets the minimum. Another fix from Craftsy: sew a narrow pieced strip, or a row of leftover blocks from the quilt top, between the panels to add the missing inches.

How to sew the backing panels

Once you know the layout, the sewing is quick. These steps follow APQS's guide to piecing quilt backs and Hailey Stitches' backing tutorial.

1. Cut the yardage into panels. For the queen with horizontal seams, cut 3 panels of 98 inches each.
2. Trim the selvages off the edges you will sew together. They have a tighter weave than the rest of the fabric and can pucker the seam.
3. Pin two panels with right sides together along the long edge. Pins help keep large pieces of fabric lined up.
4. Sew with a ½ inch seam allowance. APQS suggests a shorter stitch, 10 to 12 stitches per inch, for a sturdy seam, and a walking foot on long seams so the layers don't shift.
5. Press the seam open. A seam pressed to one side makes a ridge, and APQS shows how it bulges around the rollers of a longarm frame.
6. Add the third panel the same way if you need one. Then trim any extra so the backing is the size you worked out.

APQS also has a shortcut for selvages. Measure the selvage width and add ½ inch. Put a strip of painter's tape that far to the right of the needle. Sew with the fabric edges against the tape, then trim the selvage off, leaving a ½ inch seam allowance.

Where to put the seam

APQS advises against a seam right down the center of the backing. Quilts often get folded in half, so a center seam takes extra wear and can hold a crease. Offset a single seam to the left or right. Or center one full panel and add two narrower panels at the sides, which gives two seams placed evenly. Sources differ here: Hailey Stitches trims a two-panel backing evenly on all sides to keep its seam centered.

For a quilt sent to a longarm quilter, a horizontal seam can lie parallel to the frame's rollers, which makes loading easier. Hailey Stitches notes that longarm quilters typically prefer horizontal seams, and suggests asking your quilter before you sew. A quilt that will hang on a wall is different. APQS suggests running the lengthwise grain, the direction of the selvages, from top to bottom so the quilt doesn't sag. Craftsy adds a related tip: join panels along matching grain, so a stretchier crosswise edge isn't sewn to a firmer lengthwise one.

If the backing is a large print, the seam allowance can break up the pattern. Craftsy suggests trimming a little extra off one panel so the print lines up across the seam.

Backing yardage for common quilt sizes

These numbers come from the quilt calculator at its default settings: 4 inches overage per side, 42 inch fabric, 2 inches of selvage trim and ½ inch seam allowances. The last column shows the same quilt on 108 inch wide backing.

Quilt sizes vary between patterns and charts, so check yours against the quilt size chart or just measure the finished top.

As a cross-check, Hailey Stitches publishes a backing chart for six quilt sizes. It uses the same 4 inch overage and 42 inch fabric but rounds up to the next ¼ yard. Run through the calculator, 5 of those 6 sizes come out at exactly the same yardage. The baby quilt (30 by 40 inches) comes to 1⅜ yards here against 1½ in her chart, because the calculator rounds to the ⅛ yard step instead of the ¼.

When wide backing avoids seams

Wide backing fabric comes in widths such as 90, 108 and 118 inches. It lets you skip seams on larger quilts, which saves cutting and sewing.

The test is whether the usable width, after trimming selvages, is at least as big as one side of the backing. For the queen backing of 98 by 103 inches, 108 inch fabric leaves 106 usable inches. That covers either side, so one piece is enough, and the calculator turns it to use the shorter cut: 2¾ yards with no seam. With 90 inch fabric there are only 88 usable inches, which is less than both sides, so the queen still needs a seam and 5½ yards.

Prices vary, so compare the total cost of both options before you decide.

Sheets, flannel and minky

Some quilters skip piecing by backing a quilt with something wider than quilting cotton. Craftsy mentions bed sheets as a quick way to get a large patterned back. Hailey Stitches says a cotton sheet should be 100% cotton, and you should wash a flannel sheet first because flannel tends to shrink more than cotton. Craftsy also mentions minky, a soft synthetic fabric. It is wide, but it stretches and doesn't shrink, so Craftsy suggests pre-washing the quilt top if you plan to back it with minky.

Batting

Batting needs the same overage as the backing, so for the queen that is 98 by 103 inches. Packaged batting sizes don't line up exactly with quilt sizes. A queen package in the calculator's list is 90 by 108 inches, which is narrower than 98 inches, so it picks King (120" × 120"). Batting is also sold by the yard from wide rolls if a package would waste too much.

To work out backing, binding and batting for your own quilt in one go, use the quilt calculator. For fabric for the quilt top itself, the fabric yardage calculator handles cut pieces.

Sources and further reading

• Craftsy: how to piece a quilt backing.
• APQS: how to piece quilt backs.
• Hailey Stitches: how to piece quilt backing.
• Quilted Joy: how much backing fabric you need.

Video tutorial

"🤩 🤚 EVERYTHING YOU NEED TO KNOW ABOUT QUILT BACKING - FINISH YOUR QUILT" by Just Get it Done Quilts, on YouTube. The video loads only when you press play.