What You Need Before You Start

Sewing a sweatshirt means working with a pattern, fabric, and a sewing machine to create a finished garment. You will need a commercial sweatshirt pattern (brands like Simplicity, McCall's, or Burda sell these at fabric stores), a piece of sweatshirt knit fabric (usually fleece or French terry), thread that matches your fabric, a sewing machine that can handle knits, and basic tools: scissors, pins, a measuring tape, and a seam ripper for mistakes.

The pattern comes as tissue paper pieces with printed lines showing where to cut and sew. Most patterns include a size chart so you can choose the right size before cutting. Sweatshirt patterns are beginner-friendly because the seams are straight, the fit is forgiving, and mistakes are less visible than in fitted garments.

Key Takeaways

  • Choose a pattern size by measuring your chest and comparing it to the pattern's size chart, not by your usual clothing size.
  • Lay pattern pieces on folded fabric with the grain line marked on the pattern running parallel to the fabric edge, then pin and cut carefully.
  • Use a ballpoint needle and a stretch stitch on your machine, or a regular stitch with a walking foot, to prevent skipped stitches in knit fabric.
  • Sew the shoulder seams first, then attach the sleeves, then sew the side seams and sleeve seams in one continuous line.
  • Finish the neckline, cuffs, and hem with ribbing or a twin needle, which allows the fabric to stretch without breaking stitches.

Choosing Your Size and Preparing the Pattern

Do not use your regular clothing size. Instead, measure your chest at the fullest point (across your bust or chest, keeping the tape parallel to the ground) and compare that number to the size chart printed on the pattern envelope. Most sweatshirt patterns run one to two sizes larger than fitted garments, so a person who wears a size 8 dress might cut a size 4 sweatshirt. Write your chosen size on the pattern pieces with a pen before you cut anything.

Lay the pattern pieces flat on a clean table and read the instruction sheet that came with the pattern. It will show you which pieces to cut, how many of each, and whether to cut on a fold or as separate pieces. Mark any notches (small triangles cut into the seam allowance) with a pen—these help you match pieces later. If the pattern says to cut two sleeves, for example, you will flip the pattern piece over for the second sleeve so both sleeves face the same direction.

Laying Out and Cutting Your Fabric

Fold your sweatshirt fabric in half lengthwise, with the right side (the finished side you want showing) facing inward. Lay the pattern pieces on the folded fabric according to the layout diagram on the instruction sheet. The diagram shows the most efficient way to arrange pieces so you do not waste fabric. Pin each pattern piece to the fabric with at least four pins, placing them inside the seam allowance so they do not leave holes in the finished garment.

Cut slowly and carefully along the printed line on each pattern piece, using sharp fabric scissors. Do not use pinking shears or rotary cutters for this—a straight edge and sharp scissors give you the control you need. After cutting, remove the pins and pattern pieces, then transfer the notches to your fabric pieces by making small cuts or marking them with a fabric pen. These marks are your guides for matching pieces when you sew.

Setting Up Your Machine for Knit Fabric

Sweatshirt fabric is a knit, which means it stretches and can skip stitches if your machine is not set correctly. Use a ballpoint needle (size 80/12 or 90/14) instead of a regular needle—the rounded tip slides between fibers instead of piercing them, which prevents laddering (runs in the fabric). If your machine has a stretch stitch setting, use that instead of a straight stitch. A stretch stitch has a small backward motion that allows the thread to give when the fabric stretches.

If your machine does not have a stretch stitch, use a regular straight stitch with a walking foot attached. A walking foot feeds the top and bottom layers of fabric at the same speed, preventing puckering and skipped stitches. Set your stitch length to 2.5 millimeters (slightly longer than normal) and thread tension to normal. Test your settings on a scrap of sweatshirt fabric folded in half before you sew on your garment pieces.

Sewing the Main Seams in Order

Start by sewing the two shoulder seams. Place the front and back pieces with right sides together (the finished sides facing each other), align the shoulder edges, and pin them. Sew from the armhole edge to the neckline edge using a 5/8-inch seam allowance (the distance from the edge of the fabric to your stitching line). Backstitch at the beginning and end to lock the thread. Repeat for the second shoulder seam.

Next, attach the sleeves. Fold one sleeve in half lengthwise with right sides together and sew the underarm seam from the cuff to the armhole. Repeat for the second sleeve. Then pin one sleeve into the armhole opening, matching the notches and the shoulder seam, with right sides together. Sew all the way around the armhole. Repeat for the second sleeve. Finally, sew the side seams and the rest of the sleeve seams in one continuous line from the cuff, down the underarm, and down the side of the body. This creates a smooth, uninterrupted seam.

Finishing the Neckline, Cuffs, and Hem

The neckline, cuffs, and hem need to stretch with the fabric, so they are usually finished with ribbing or a twin needle. If your pattern includes ribbing strips, cut them to the width and length specified. Fold the ribbing in half lengthwise with wrong sides together (so the fold is on the outside), then pin it to the neckline opening with right sides together. Stretch the ribbing slightly as you pin so it lies flat. Sew with a 1/2-inch seam allowance, then fold the ribbing to the inside and topstitch it down with a twin needle or a regular stitch.

A twin needle is two needles on one shaft that create two parallel rows of stitching on the top and a zigzag on the bottom, which allows the seam to stretch. Thread your machine with two spools of thread and follow your machine's manual for twin needle setup. Sew the cuffs and hem the same way: fold the ribbing or fabric edge in half, pin it, and sew with the twin needle. Press all seams flat with an iron on a low setting (knits can melt), and your sweatshirt is finished.

Common Mistakes and How to Avoid Them

The most common mistake is using the wrong needle or stitch setting, which causes skipped stitches and a puckered seam. Test on scrap fabric first, every time. Another mistake is sewing too fast—slow down and let the machine feed the fabric at its own pace. If you rush, the needle can bend or break, and your stitches will be uneven.

Stretching the fabric while you sew is also common. Let the machine do the work. Your hands should guide the fabric gently, not pull it. If you pull, the seam will pucker when the fabric relaxes. Finally, do not skip the notches. Matching notches takes 30 seconds and prevents sleeves from twisting or the back from bunching. If you sew without them, you will have to rip out seams and start over.

Frequently Asked Questions

Can I sew a sweatshirt on a regular sewing machine without a walking foot?

Yes, if you use a ballpoint needle and a stretch stitch. The stretch stitch compensates for the fabric movement. If your machine has neither, use a regular stitch with the needle tension slightly loosened and test on scrap fabric first. A walking foot is helpful but not required if your machine has a stretch stitch.

What happens if I use regular thread instead of thread made for knits?

Regular thread is stiffer and less forgiving, so it can break when the fabric stretches. Polyester or cotton-wrapped polyester thread works fine for sweatshirts. You do not need specialty "stretch thread"—just use good-quality thread and a ballpoint needle.

How do I fix skipped stitches after I have already sewn the seam?

Use a seam ripper to carefully cut and remove the stitches, then resew the seam with the correct needle and stitch setting. Check your machine setup on scrap fabric before you sew again. Skipped stitches usually mean the needle is dull, the wrong size, or the stitch setting is incorrect.

Do I need to pre-wash sweatshirt fabric before I cut and sew?

Yes. Sweatshirt knits can shrink, especially fleece. Wash and dry the fabric the same way you plan to wash the finished sweatshirt, then let it cool completely before you lay out the pattern. This prevents the finished garment from shrinking after you wear it.

Can I add pockets to a sweatshirt pattern that does not include them?

Yes, but add them before you sew the side seams. Cut two pocket pieces from your fabric, sew them to the front pieces along the pocket opening line, then fold and press them to the inside. Topstitch around the pocket opening to hold it in place. This is easier than trying to add pockets after the garment is assembled.