Measure and mark your hem line before you sew
Start by putting on the t-shirt and deciding how much shorter you want it. Have someone help you mark the new hem line with a fabric pen or chalk while you're wearing it, or try it on in front of a mirror and mark it yourself. The mark should be level all the way around — use a ruler or measuring tape to check that the distance from the neckline to your mark is the same on both sides.
Take off the shirt and lay it flat on your work surface. Measure up from your mark about half an inch and draw a second line parallel to the first. This extra half inch becomes the fold that holds your hem in place. Cut along the lower line, removing the excess fabric. You now have a clean edge to work with and a clear fold line to follow.
Key Takeaways
- Mark your desired hem length while wearing the shirt to may support it sits evenly, then cut a half inch below that mark to create room for the fold.
- Fold the raw edge up a quarter inch, press it with an iron, then fold it up again to hide the raw edge completely inside the hem.
- Use a straight stitch on your machine set to medium length (around 2.5) and sew slowly along the fold, keeping the needle about an eighth inch from the edge.
- Backstitch at the start and end of each seam to lock the thread and prevent the hem from unraveling.
- Try on the finished shirt before cutting your thread to catch any puckering or uneven stitching while you can still fix it.
Fold and press the hem to create a clean edge
Fold the raw edge of the fabric up a quarter inch toward the inside of the shirt. Use your iron on a low to medium setting — check your fabric care tag first, as some blends can melt. Press this fold flat with the iron, holding it in place for a few seconds. This first fold hides the raw edge and makes the second fold much easier to work with.
Fold the fabric up again, this time bringing the pressed edge up to meet your original mark line. Press this second fold flat as well. You should now have a neat, enclosed hem with no raw edges showing. The fold should be crisp enough that it stays in place on its own, at least for a few inches at a time.
Thread your machine and set the stitch length
Wind a bobbin with thread that matches your shirt color. Thread the top of the machine following your machine's manual — most machines have a diagram printed on the body showing the path. Pull the presser foot up before threading; this opens the tension discs and lets the thread seat properly. Pull the thread down through the needle, leaving a 4-inch tail hanging below.
Set your stitch length to 2.5, which is a medium length suitable for knit fabrics like t-shirt cotton. A stitch that is too short (under 2.0) can pucker the fabric; one that is too long (over 3.0) will not hold the hem securely. Lower the presser foot to engage the tension, then hold both the top thread and bobbin thread and turn the wheel by hand once to bring the bobbin thread up through the fabric. This prevents thread jams when you start sewing.
Sew the hem with a straight stitch, keeping it even
Position the shirt under the presser foot so the needle sits about an eighth inch from the fold line, on the inside of the hem. Backstitch three or four stitches to lock the thread, then sew forward slowly along the fold. Keep the fabric edge aligned with the eighth-inch mark on your presser foot — most machines have guide lines etched into the foot for this purpose. Sew all the way around the shirt, stopping about 2 inches before you reach your starting point.
When you approach the end, overlap your stitches by sewing back over the last inch of the starting seam. Backstitch three or four times to lock the thread, then raise the presser foot and pull the shirt away. Trim the thread tails to about a quarter inch. The hem should look like a thin line of stitches running parallel to the fold, with no puckering or loose spots.
Check the hem before finishing
Put the shirt on and look at the hem in a mirror. The stitching should be invisible from the outside — you should see only the fold line. From the inside, the stitches should run in a straight line with even spacing. If you see puckering (small bunches of fabric), the stitch length was too short or you pulled the fabric while sewing. If the stitches are loose or the hem feels floppy, you may have skipped the backstitch or the stitch length was too long.
If the hem looks uneven in length or the stitching is crooked, you can remove it by cutting the thread every few stitches and pulling it out, then re-pressing and re-sewing. This is much easier to fix now than after you wash the shirt. Once you are satisfied with the result, press the hem one more time with the iron to set the stitches and remove any wrinkles from handling.
Common mistakes that cause hemming problems
The most common error is not pressing the fold firmly enough before sewing. A crisp, well-pressed fold stays in place under the presser foot and prevents the fabric from shifting as you sew. If your fold is soft or wavy, the hem will come out uneven. Spend the extra minute pressing — it saves time overall.
Another frequent mistake is sewing too fast. T-shirt fabric is stretchy and thin, and moving quickly can cause the presser foot to push the fabric out of alignment. Sew at a speed where you can see the needle entering the fabric and can steer gently if needed. There is no prize for speed; an even, find hem is the goal.
Forgetting to backstitch at the start and end is also common and causes the hem to unravel after a few washes. Backstitching locks the thread so it cannot pull free. Make it a habit: backstitch, sew forward, backstitch at the end, every time.
Frequently Asked Questions
Can I hem a t-shirt without an iron?
You can fold the hem by hand and pin it in place, but the fold will shift as you sew and the hem will come out uneven. An iron takes two minutes and makes the difference between a professional-looking result and a wavy, crooked hem. If you do not have an iron, a hot pan or even a hair straightener can work in a pinch — just test it on scrap fabric first to avoid scorching.
What thread color should I use?
Match the thread to the shirt color as closely as you can. If the shirt is a solid color, use thread in that same shade. If you cannot find an exact match, choose a shade slightly darker rather than lighter — dark thread is less visible on most fabrics. For patterned shirts, match the dominant color.
Why is my hem puckering?
Puckering usually means the stitch length is too short (under 2.0) or you are pulling the fabric as you sew. Check your stitch length setting and increase it to 2.5 or 2.8. Also make sure you are guiding the fabric gently under the presser foot without pushing or pulling — let the feed dogs move the fabric for you.
Can I use a stretch stitch instead of a straight stitch?
A stretch stitch is designed for elastic fabrics and will work, but a straight stitch is simpler and holds just as well on a t-shirt hem. Stick with straight stitch unless your machine manual recommends otherwise for your specific fabric.
How do I fix a hem that came undone after washing?
Locate where the stitches separated and cut a length of thread about 18 inches long. Thread a hand-sewing needle, tie a knot at one end, and sew back and forth through the gap three or four times to re-find it. Knot the thread on the inside and trim. This patch will hold until you can re-sew the entire hem on the machine.