T-Shirt Quilt Planner: How Many Shirts Do You Need?

How to work out the number of shirts

Start with your block size. Measure the largest design you want to keep and add at least an inch or two around it, then round up to a size that works for all of your shirts. A 12 in block suits smaller designs and children’s shirts, a 14 in block suits most adult shirts, and 16 in gives large designs room to breathe. Larger blocks mean fewer shirts for the same quilt, but they also mean that small logos can look lost.

Next, divide the quilt size by the block size plus the sashing. A throw of 50 x 65 in, with 14 in blocks and 2 in sashing, fits 3 blocks across and 4 down. That is 12 blocks, and it finishes at 50 x 66 in, once you include sashing on the outside edge. Since blocks only come in whole numbers, the finished quilt will land near your target rather than exactly on it, and the planner tells you the real size.

Why you need fusible interfacing

T-shirt fabric is a knit, and knits stretch in a way that woven quilting cotton does not. If you sew a knit to a woven without stabilizing it, the seams will ripple and your blocks will end up in different sizes. The answer is a lightweight fusible knit interfacing, ironed to the back of each shirt before you cut. It holds the knit steady while still leaving the quilt soft enough to enjoy.

Pellon SF101 is a popular choice for this, and our catalog includes a range of stabilizers too. Follow the maker’s directions for heat and time. Do not slide the iron around, as that can stretch the knit. Press down, lift, and move on. The planner assumes squares of interfacing 1 in larger than your cut block, from a 20 in wide bolt, since a bit of extra room makes it easy to line up the design.

Cutting the shirts

Wash and dry all of the shirts first, without fabric softener, so the interfacing bonds well. Cut each one apart, along the side seams and across the shoulders, to get a flat panel that is easy to work with. Fuse the interfacing to the back of the design, then place a large square ruler over it. A clear ruler lets you center the design, and you can cut all four sides to your block size plus 1/2 in for seams.

Watch out for designs that have raised prints or plastic-feel inks. The iron can melt these, so use a pressing cloth on the right side, and always press from the back whenever you can. If a design is too small for the block, add strips of fabric around it, like a small frame, until it reaches the right size. This is a neat way to include baby clothes, pockets or small logos alongside larger shirts.

Sashing or no sashing?

Sashing is the strip of fabric between the blocks. It gives each design a clean frame, adds size without needing more shirts, and makes the layout more forgiving, since a slight difference in block size is easier to hide. A strip of 2 in is a common choice. It can also add a splash of team color, or a calm neutral that lets busy designs stand out.

Sewing blocks directly together is quicker, and it gives a bold, patchwork look. But knit seams can be bulky where they meet, and the differences in block size are more obvious. To see the difference, set the sashing to 0 in the planner, and compare the number of blocks you need. Then think about color. Lay your shirts out on the floor, take a photo, and move them around until no two strong colors or similar designs sit side by side.

Finishing your T-shirt quilt

Batting and backing work the same as on any other quilt, so use your finished size in the quilt backing calculator and batting size calculator. Fleece is a popular backing for these quilts because it is warm and soft, and it matches the casual feel of the shirts. Keep in mind that fleece stretches, so a longarm quilter may have a preference. Ask before you buy.

Quilt it simply. A wavy line or an all-over meander near the seams works well, and it avoids stitching across the printed designs, where the needle can leave holes and the plastic-like inks can gum up your machine. Use a stretch or ballpoint needle if you notice skipped stitches. Finish the edges with the quilt binding calculator. You can also add a label with the name, dates and story behind the shirts, since these quilts are often treasured for a long time.

Common T-shirt quilt mistakes to avoid

Skipping the interfacing is the mistake people regret the most, as the knit will ripple and stretch as soon as you start to sew. The next most common mistake is cutting the blocks before you fuse them. Fusing can change the size of the knit a little, so always fuse first and cut afterward, with the design centered under your ruler. Another mistake is choosing a block size to suit the smallest design. If you pick a size that fits your largest design, you can add strips of fabric around the smaller ones to bring them up to size.

It also helps to think about which shirts you might regret cutting. Once you cut a shirt, you cannot put it back together, so set aside anything you are unsure about and lay out the quilt before you commit. Thick prints and appliqued numbers can be hard to sew through, so use a larger needle and sew slowly through them, or plan your seams around them. Finally, try to keep heavy items, such as thick sweatshirts or jersey numbers, spread around the quilt. If they all sit on one side, it may hang unevenly, and it could be harder to quilt.