If a T-shirt is too wide through the body, you can take it in at the side seams for a closer fit. The alteration works best when the shoulders, sleeve openings, and neckline already fit. Mark both sides evenly while wearing the shirt, baste the new seam first, and check comfort before trimming fabric. Knit material stretches, so use a stitch and finish that suit the garment.
Quick answer
Turn the shirt inside out, put it on, and pin or mark the amount to remove from each side. Take the same amount from both seams unless the garment or your fit requires otherwise. Draw a smooth line that begins below the sleeve seam and blends into the existing side seam, baste it, try the shirt on, and only then sew permanently. Do not cut off excess fabric until the fit is approved.
Check whether taking in will solve the fit issue
Look at the shirt from the front, side, and back. If the shoulders fit and the extra fabric is mainly at the waist or torso, adjusting the side seams may help. If the shoulder seams hang far below your shoulder or the armholes are too low, taking in the sides may create tightness or folds under the arms without correcting the main issue.
Check the shirt while sitting, reaching, and raising your arms. A fitted tee still needs room to move and breathe. If the shirt has a side graphic, pocket, or a seam detail, note whether the alteration would distort or remove it. Compare a garment that fits well against the site’s T-shirt sizing guide before you start.
Gather tools and prepare the shirt
You will need a sewing machine that can handle knit fabric, an appropriate needle and thread, pins or clips, a fabric marker or tailor’s chalk, a ruler, and fabric scissors. If you have not sewn jersey before, practice on scraps or a hidden section of similar material. Follow the machine’s guide and use a stitch that can stretch with the fabric.
Wash and dry the garment according to its care label before altering if it may change size. Let it lie flat, turn it inside out, and smooth it without stretching. Avoid sewing through a print, label, or decorative element unless you intend to alter it.
Mark both sides evenly
Wear the shirt inside out with the seams visible. Pin the extra width at both side seams, working in small, even amounts. If someone can help, ask them to pin the fabric while you stand naturally. Check that the shirt still moves comfortably and that the front and back hang evenly. Take it off carefully so the pins stay in place.
Lay the shirt flat and compare both sides. Mark the planned new seam with a smooth line, starting near the underarm and tapering into the existing seam. A sudden angle can create a ridge. Use the same measurements on both sides and confirm that the hem remains level when the shirt is worn.
Baste, try on, and adjust
Sew the planned line with a temporary long stitch or hand-baste so you can remove it if needed. Try the shirt on right side out and check the chest, waist, hem, sleeve movement, and comfort. If it pulls or rides up, remove some of the adjustment. If the fit still feels loose, mark a small additional change and test again.
Do not rely on a mannequin or flat measurement alone. Knit fabric can stretch differently on a body than on the table. Make gradual changes on both sides rather than taking a large amount from one seam. If the garment has a side seam that meets the sleeve, start the taper below the armhole and blend it gently into the original line.
Sew and finish the new seam
| Step | What to do | Check |
|---|---|---|
| 1. Pin and mark | Measure matching changes at both sides | Shoulder and sleeve fit remain acceptable |
| 2. Baste | Temporary stitch the new seam line | Body is comfortable when moving |
| 3. Sew | Use a suitable stretch stitch and seam allowance | Fabric feeds without stretching or puckering |
| 4. Try again | Check fit after the permanent stitching | Hem and side seams hang evenly |
| 5. Trim and finish | Remove excess only after final approval | Seam allowance is secure and comfortable |
Use an appropriate stretch stitch or serger setup and sew slowly. Avoid pulling the fabric as it passes under the presser foot, because that can make the side seam wavy. Try the shirt again before trimming. If you cut excess fabric, leave a sensible seam allowance and finish the edge so it does not irritate the wearer.
When a different alteration is better
If the shoulders, armholes, neckline, or sleeve width are the main problem, side seams alone may not produce a balanced fit. A shirt with a large print running close to the side may not be a good candidate. If the garment is expensive, sentimental, or part of a group uniform, test the alteration on a less important shirt or ask a tailor.
A shopper replacing a shirt can compare measurements before ordering rather than alter every garment afterward. Browse in-stock T-shirts or review custom T-shirt options with a fit that better suits the intended use.
Practical example
A volunteer has a team T-shirt that fits at the shoulders but feels loose around the waist. They wear it inside out, pin a small amount from each side, and baste the seams. After walking and reaching, they adjust the fit slightly, then sew both sides and trim only after the final check. A different shirt with drooping shoulders would need a more complete alteration, so the same side-seam fix would not solve it.
Frequently asked questions
Can I take in a T-shirt without a sewing machine?
Hand sewing may work for a small adjustment if the stitch can stretch and the seam is secure. Test on scrap fabric and avoid stiff stitches that pop when the shirt is worn.
Should I cut away the extra fabric right away?
No. Baste and try on first. Keep the excess until the fit and movement are approved.
Why does the new seam pucker?
The knit may have stretched during sewing, or the needle, stitch, or tension may not suit it. Test adjustments on scraps before sewing the garment again.
Can I take in a shirt with a side print?
Possibly, but the seam may cut into or distort the artwork. Inspect the print placement before marking the alteration.
