How to make a t-shirt

1. Materials & tools

Materials (women's M to men's L)

• Knit fabric (cotton jersey, interlock, etc.) — about 150 × 100 cm (60 × 40 in); about 170 cm (67 in) long if it is 110 cm (44 in) wide
• Fusible stay tape for the shoulders (thin or very stretchy knits) — about 30 cm (12 in)
• Ballpoint / stretch machine needle and polyester thread for knits

Tools

• Sewing machine (or needle and thread)
• Fabric marker or pencil
• Ruler and scissors
• Iron
• Pins or clips

2. Make the pattern (auto-generated in Katagami)

With the Katagami pattern tool, you just enter the finished size and it drafts a seam-allowance-included pattern, tiled to print at actual size on Letter or A4.

1. Open the tool
   Open the pattern tool and choose “Adult clothes” → “T-shirt” from the tabs at the top.
2. Enter the size
   Enter your bust, length, shoulder width, sleeve length, cuff circumference, neckline width and ease, or start from a size preset. Cuff circumference is the distance around the sleeve once it is sewn into a tube — for a short sleeve, allow your upper-arm measurement plus at least 4 cm (1.5 in). With “Add a neckband” on, the pattern includes a neckband 90% of the neckline length. Set the seam allowance to 1 cm (3/8 in); these steps assume it.
3. Set the seam allowance
   Use the slider at the bottom (beginners: 1.0–1.5 cm / about 3/8–5/8 in).
4. Print
   Press “Print (actual size)”, then in the print dialog set Scale = 100% and turn “Fit to page” OFF. Check the 50 mm calibration box on the first guide sheet with a ruler.

3. Cutting the fabric

1. Check the stretch
   Knits stretch most across the width. Lay the body and sleeves with the grainline parallel to the selvage so the stretch goes around the body. Lay the neckband with its long side across the width (the stretchiest direction).
2. Cut
   Cut the front and the back on the fold (1 each), 2 sleeves and 1 neckband. The front neckline is deeper than the back, so keep them apart.
3. Mark the notches
   Snip about 3 mm (1/8 in) into the allowance at the center of the sleeve cap, at the bottom of each armhole on the body, and at the quarter marks on the neckband.
4. Stabilize the shoulders
   On thin or very stretchy knits, iron stay tape onto the shoulder allowance of the back so the shoulders don't stretch out of shape.

4. Sewing

Sewing steps in pictures 15 steps, one at a time

4-1. Sew the shoulders

1. Place the front and back right sides together and sew both shoulders with a 1 cm (3/8 in) seam. Zigzag the raw edges together (or sew the seam on a serger if you have one).
   See it in pictures
2. Press the allowances toward the back.
   See it in pictures

4-2. Attach the neckband

1. Sew the short ends of the neckband right sides together to make a loop. Press the seam open.
   See it in pictures
2. Fold it in half lengthwise, wrong sides together, and press the fold. Stretch it over your head now to check that it fits.
   See it in pictures
3. Put the neckband seam at center back. Match its quarter marks to the neckline divided into four (center front, center back and the two points halfway between) and pin.
   See it in pictures
4. With the band on the right side of the neckline, stretch it gently to fit and sew round with a 1 cm (3/8 in) seam. Zigzag the allowances together, press them toward the body and topstitch from the right side.
   See it in pictures

4-3. Set in the sleeves

1. Open the body out flat. Pin a sleeve to the armhole right sides together, matching the cap notch to the shoulder seam and the sleeve ends to the notches at the bottom of the armhole.
   See it in pictures
2. Sew along the armhole with a 1 cm (3/8 in) seam, zigzag the allowances and press them toward the body. Repeat for the other sleeve.
   See it in pictures

4-4. Sew the sleeves and sides

1. Fold the front and back right sides together and match the sleeve seams at the underarm.
   See it in pictures
2. Sew from the cuff, through the underarm, down to the hem in one continuous 1 cm (3/8 in) seam and zigzag the allowances. Repeat on the other side.
   See it in pictures

4-5. Hem the cuffs and body

1. Turn up the hem allowance on the pattern — 2 cm (3/4 in) on the cuffs and 2.5 cm (1 in) on the body — and press.
   See it in pictures
2. Stitch round from the right side with a zigzag or a stretch stitch (or a twin needle if you have one), and you're done.
   See it in pictures

✏️ The neckband is 10% shorter than the neckline. Stretching it slightly as you sew makes the neckline lie flat against the neck. If a seam goes wavy, a shot of steam from the iron will settle it.

5. Tips & variations

• Check the head opening first: knits vary. For a firm, less stretchy knit, widen the neckline in the tool by 1–2 cm (1/2–3/4 in).
• No serger? Switch to a ballpoint needle and use a narrow zigzag so the stitches stretch with the fabric instead of snapping.
• Don't push the fabric: knits stretch under the presser foot. Let the feed dogs move it rather than pulling.
• Make it your own: lengthen the body for a tunic or the sleeves for a long-sleeve tee. For long sleeves, make the cuff circumference big enough for your hand to pass (about 20 cm / 8 in or more).