Double Needle Stitching: What It Means on a T Shirt
What double needle stitching is, how it differs from single needle and coverstitch, where it shows up on t shirts, how to read it on a spec sheet and decorating near hems.
Stitch types table, how double needle hems are made, where they appear on a tee, spec sheet terms and printing or pressing near hems and seams.
Double needle stitching is two parallel rows of stitches, usually on t shirt sleeve hems, bottom hems and collars, made by a twin needle or a coverstitch machine; it gives a flat, finished edge with some stretch, and blank spec sheets list it so buyers can compare construction.
Rule: "double needle" on a spec sheet describes what you see on the outside, two rows of stitching. It does not tell you which machine made the hem or how far it will stretch, so ask the supplier when hem stretch matters for the order.
Part of the business and pricing guides in the DAX Learning Hub. For the wider blank sourcing picture, see Wholesale Blanks Buying.
Stitching Types on Blanks
Four stitch types come up most often when you compare t shirt blanks. They can look alike from a distance, so turn the hem over and check the inside.
| Stitch | Look on the outside | Inside and stretch | Where it is used |
|---|---|---|---|
| Single needle | One row of straight stitching | Single row; less give than a coverstitch | Older vintage tees and some modern reproduction or small run blanks |
| Double needle (twin needle) | Two parallel rows | Bobbin thread zigzags between the rows; some stretch, less than a coverstitch | Knit hems sewn on a standard lockstitch machine |
| Coverstitch | Two or three parallel rows | Looper thread chains across the back and covers the raw edge; stretches and recovers | Sleeve and bottom hems and neckbands on most knit tees |
| Flatlock | Flat band of stitching across a seam | Encloses both raw edges in a flat seam that withstands stretch | Seams on activewear and some specialty knits |
How Double Needle Stitching Is Made
There are two common routes to the same two row look. A coverstitch machine sews two or three needle threads on the face while a looper thread chains between them on the back. That looper thread has slack built in, so the hem stretches with the knit and recovers, and it covers the raw edge in one pass. Sewing guides note that most knit t shirts sold in stores are hemmed this way.
A twin needle on a standard sewing machine imitates the look: two needles on one shank sew parallel rows on the face, and the bobbin thread zigzags between them underneath. It works on knits, but it stretches less than a coverstitch and some fabrics tunnel, forming a raised ridge between the rows.
Row spacing varies. On tee hems the two rows are commonly a few millimeters apart, roughly 3 to 6 mm (about 1/8 to 1/4 inch), with wider settings used on heavier knits such as sweatshirt fleece. Treat those figures as typical, not a standard, and check the blank maker spec.
The trade terms are used loosely. Some supplier glossaries treat double needle as a lockstitch and coverstitch as a separate machine class, while others list both as "double needle" because they look the same from the outside. If stretch recovery at the hem matters, for example on fitted or stretch blanks, ask which construction the blank actually uses.
Where It Shows Up on a T Shirt
On a typical modern tee you will find double needle or coverstitch construction at the sleeve hems and the bottom hem, and often at the collar or neckband. Some garments use a triple needle finish, three rows instead of two, on heavier hems and bands.
Hem stitching is also a known dating clue on vintage tees. Single needle hems were standard on US made blanks through the 1980s, and the change to double needle hems spread through the middle 1990s, maker by maker rather than on one date. Vintage guides stress that stitching alone does not prove a shirt's age, since reproductions and some small runs still use a single needle.
Reading Construction on a Spec Sheet
Blank spec sheets and catalogs usually list construction in short bullets. Common phrases include:
| Spec sheet phrase | What it means |
|---|---|
| Double needle sleeve and bottom hems | Two visible rows of stitching on the sleeve openings and the bottom hem |
| Double needle collar or neck | Two rows stitched around the neckband |
| Coverseamed neck or armholes | Parallel rows of visible stitching used to finish the neck or armholes |
| Triple needle | Three parallel rows, often on heavier hems or bands |
| Side seamed or tubular body | Whether the body has sewn side seams or is knit as a tube |
On most modern blanks, double needle hems are a baseline feature rather than a premium extra, so they rarely separate one blank from another. Weigh them alongside fabric weight, fiber content, yarn type and the measurement chart. For fabric basics, see What Is Jersey Fabric and Ring Spun vs Combed Cotton; to check fit, use How to Measure a T Shirt.
Decoration Near Hems and Seams
Hems and seams are thicker than the surrounding fabric, which matters for both screen printing and heat pressing. Print shops generally avoid printing across raised seams and hems, because the step in height can interfere with ink deposit and print quality. Plan hem placements with a margin above the stitching rather than across it.
For heat transfers near a hem or seam, the goal is a flat print area. Let raised hems hang off the edge of the platen where the design allows, or place a heat press pillow or pad under the print area so the seam sinks into it while the decorating area stays raised. Pads change how pressure reaches the transfer, so adjust pressure and test on a spare before the run.
Frequently Asked Questions About Double Needle Stitching (FAQ)
What does double needle stitching mean?
It means two parallel rows of stitching, usually at the sleeve and bottom hems and sometimes the collar. On a spec sheet it describes the visible finish.
Double needle vs single needle: what is the difference?
Single needle is one row of stitching; double needle is two parallel rows. Single needle hems were common on older US made tees, while two rows are standard on most modern blanks.
Is double needle stitching better?
It depends on the use. Two rows give a flat, finished hem and are standard on most modern tees, while single needle hems are chosen for a vintage look. For stretch blanks, ask whether the hem is coverstitched.
What is a coverstitch hem?
A hem made on a coverstitch machine: two or three rows of stitching on the outside and a looper thread chained across the back, which stretches and recovers with knit fabric.
Can you print over a double needle seam?
It is usually avoided. Keep screen prints and transfers clear of raised hems and seams, or use a heat press pillow or pad so the print area sits flat, and test first.
Supplier note: figures here are hedged starting points that vary by garment, film, ink, blank, machine and method; confirm every setting against the supplier or manufacturer spec sheet, the garment care label and your own tests. Stitch spacing and construction terms vary by maker.
Browse more guides in the DAX Learning Hub, and check cities and dates on the DAX show schedule when you are ready to see blank tees and garment construction samples in person.