Backing Fabric Basics: Sizing, Squaring, and What to Avoid
Part of the Starshine Quilting Studio Learn & Prep series
Your backing fabric is the unsung hero of a finished quilt -- and getting it right is one of the most common places first-timers run into a snag. The good news is that once you understand a few basics, it's completely straightforward.
This guide covers sizing, what 'squaring' actually means, fabric choices that work well (and a few to avoid), and how to check that your backing is ready before drop-off or mail-in day.
Big Does Your Backing Need to Be?
Your backing needs to be larger than your quilt top on all four sides -- this extra fabric wraps around the longarm leaders and holds the quilt taut while we work.
The rule of thumb: your backing should be at least 4 inches wider and 4 inches longer than your quilt top on each side. So if your quilt top is 60" x 80", your backing needs to be at least 68" x 88".
A little extra is always fine -- we'd rather have too much backing than not enough. If your backing falls short, we can add fabric as part of our Quilt Prep Service.
What Does 'Square Your Backing' Actually Mean?
It doesn't mean your backing has to be a perfect square shape. It means the backing should have reasonably straight edges that are square at the corners -- not wavy, stretched, or pulled out of shape.
Here's the quick check: fold the backing in half by width and then by length. Lay the folded backing on the floor. Does it lay flat without obvious bubbles or distortion? Do the edges lay reasonably straight without pulling or curving? If yes, you're in good shape.
If your backing has been sitting folded for a long time, pressing it before drop-off will help it relax and lay flat. This is especially important for backings made from a single width piece of fabric.
If you're piecing your backing from multiple pieces of fabric, press those seams well (just like the top) and make sure everything lays flat before you hand it off.
What Fabrics Work Well (and What to Avoid)
Most quilting cottons make excellent backing fabric. They are stable, easy to work with, and available in a wide range of beautiful prints and colors. Wide backing fabric (108" width) is an especially convenient option because it often eliminates the need for piecing.
Flannel Backing: Cozy, But a Little Different
Flannel is a wonderful backing choice when you want a quilt that feels especially soft and cozy. It is especially popular for baby quilts, winter quilts, and everyday comfort quilts.
Flannel tends to shrinks significantly more than quilting cotton, often 3–5% or more, and it can shrink unevenly. We suggest that you wash it in warm water, and dry it fully. Some quilters pre-wash twice to get all the shrinkage out before it's made part of the quilt.
Once quilted, flannel creates beautiful softness and texture that many quilters love.
Minky Backing: Soft, Luxurious, and Worth Planning For
Minky creates an exceptionally soft backing and is a favorite for baby quilts, throws, and comfort quilts.
Because Minky stretches significantly more than cotton, we recommend allowing at least 6 inches extra on all sides whenever possible.
Minky also sheds heavily when cut, so it helps to shake out or vacuum loose fibers before bringing it in.
Whenever possible, Minky works best as a single piece rather than pieced, since seams can add bulk and make loading more challenging.
Some quilting designs show beautifully on Minky, while very dense quilting can reduce some of its softness. If you are planning to use Minky, please mention it on your intake form so we can plan accordingly.
Fabrics to Avoid
Stretchy or knit fabrics as well as loosely woven fabrics are generally not recommended.
Flat bedsheets — especially high-thread-count sheets — are often tightly woven in a way that can make quilting more difficult and may affect stitch quality.
Not sure about your fabric? Just ask -- we're happy to take a look.
Piecing Your BackinG
If your backing fabric is not wide enough on its own, you will need to piece two or more sections together to create the size you need.
A few simple choices during piecing can make a big difference once the quilt is loaded on the longarm.
Helpful tips:
If your backing is seamed, make sure it lays flat (Nest those seams and press, press, press!)
Remove selvages before sewing pieces together.
Use a consistent seam allowance so the backing stays balanced
Avoid fullness or puckering along seam lines. Pinning on a flat surface can help.
Whenever possible, avoid adding very narrow strips of fabric along one side just to gain width. Narrow side strips can stretch differently than the main backing and may affect how the quilt loads on the frame.
If you need to add width, larger balanced sections usually behave better than narrow extensions. Another option is to add the additional fabric in the center of the backing - horizontally or vertically.
A seam in the backing is perfectly acceptable. You’ll want to make sure it is well pressed and free of distortion before drop-off/mail-in. The best option is to seam the backing horizontally so that the seam runs from side to side. This prevents slight distortion that can happen if the backing is seamed vertically (top to bottom.)
Always make sure to mark the top of the backing so that the finished quilt is the way you intend.
If you would rather not piece it yourself, we offer backing piecing as an add-on service. Just note it on your intake form or mention it at drop-off.
Have questions about batting? Reach out anytime -- we're happy to help you find the right fit for your quilt.
Backing Quick Check Before You Pack It Up
[ ] Backing is at least 4 inches larger than the quilt top on all sides
(5–6 inches extra for flannel; 6 inches for Minky whenever possible)
[ ] Edges are reasonably straight — not wavy, stretched, or distorted
[ ] Backing lies flat with no obvious bubbles, fullness, or pulling
[ ] Selvage edges have been removed. (OK on top & bottom edge of provided backing)
[ ] Seams (if pieced) are pressed flat and are secure
[ ] Backing seam allowances are trimmed to reduce bulk where needed
[ ] Directional prints have been checked so the backing faces the intended direction
[ ] Backing, batting, & quilt top are packed in a plastic bag (especially impt if mailing in)
[ ] Any specialty backing (flannel, Minky, etc.) is noted on the intake form
NOTE: A more comprehensive list that includes prep for the top and batting (if providing) is available here.
Have questions? Reach out anytime -- and check out the rest of our Learn & Prep guides for everything else you need to know before drop-off day.
