Manufacturer · Fashion & Home Accessories
Thread and needle are chosen together according to the fabric: the thinner the fabric, the finer the thread and the smaller the needle. The basic rule is that the thread should fill about 40% of the needle eye – then it runs freely without rubbing and breaking. For example, polyester thread tkt 120 goes with a needle Nm 70–80, and tkt 40 with a needle Nm 100–110.
How needles are labelled
Needle size is given in the metric system (Nm) – the diameter of the blade in hundredths of a millimetre. A needle Nm 80 has a diameter of 0.8 mm. The American number is often shown next to it: 70/10, 80/12, 90/14, 100/16, 110/18, 120/19. Besides the size, the point also matters:
- sharp point – for woven fabrics, a precise straight stitch;
- ball point – for knits; it parts the loops instead of piercing them;
- cutting point – for leather and faux leather; it cuts through the material;
- denim (jeans) – a reinforced sharp point for dense cotton fabrics.
Chart: thread and needle by fabric
The values are a guide for polyester sewing thread. With cotton thread, choose one step thicker for the same strength.
| Fabric | Thread (tkt) | Needle Nm | Point |
|---|---|---|---|
| chiffon, silk, organza | 150–180 | 60–70 | fine sharp |
| poplin, batiste, shirts | 120 | 70–80 | sharp |
| fine knit, jersey, lingerie | 120–150 | 70–80 | ball point |
| cotton, linen, dresses | 100–120 | 80–90 | sharp |
| wool, suiting fabrics | 100 | 80–90 | sharp |
| sweatshirt fabric, heavy knit | 100–120 | 80–90 | ball point |
| denim, twill, workwear | 80–40 | 90–110 | denim |
| canvas, bags, heavy textiles | 40–30 | 110–120 | sharp |
| leather, faux leather | 40–20 | 100–140 | cutting |
| visible decorative stitching | 30–20 | 110–140 | depending on the fabric |
Why the thread and needle combination matters so much
Thread too thick for a thin needle
The thread does not sit freely in the needle groove, it rubs in the eye and heats up. The result is fraying, breakage and skipped stitches. On high-speed machines the problem appears within the first few minutes.
Thread too thin for a thick needle
The needle leaves visible holes and the thin thread does not fill them. The hook may fail to catch the loop and stitches are skipped. On thin fabrics the holes remain for ever.
The influence of the fabric
The density and composition of the fabric are just as important as its thickness:
- elastane and knits – need a ball point and a thread with some stretch; with a stiff thread the seam breaks when stretched;
- microfibre and dense synthetics – need a fine sharp needle, otherwise seam puckering appears;
- multi-layer seams (jeans waistbands, pockets) – the needle must be strong enough not to bend; sometimes a larger size is used just for these operations;
- coated and laminated fabrics – a fine needle and fewer stitches per centimetre, so as not to perforate the membrane.
Needle thread and bobbin thread
For straight stitching the same thread is usually used on top and in the bobbin. For decorative stitching with a thick thread (tkt 30 or 20), a finer thread (tkt 50–80) in the same colour is often put in the bobbin – the seam looks bold on top and the machine runs more steadily. Adjust the tension so that the interlocking sits in the middle of the fabric.
A short checklist before sewing
- Identify the fabric and the type of seam.
- Choose the thread from the chart and check the recommendation on the spool label.
- Fit a new needle of the right size and point.
- Sew a test seam on two pieces of the same fabric.
- Check the tension, stitch length and appearance of the seam on both sides.
- Change the needle regularly – a blunt needle damages both the fabric and the thread.
Stitch length
Thread thickness is also linked to stitch length. Fine threads and fabrics need a shorter stitch – about 2–2.5 mm, i.e. 4–5 stitches per centimetre. For general sewing of medium fabrics 2.5–3 mm is used. Decorative stitching with thick thread looks best with a longer stitch of 3.5 to 5 mm, otherwise the thread piles up and the seam becomes uneven. On leather, a stitch that is too short perforates the material like a postage stamp and reduces seam strength.
Special cases
- Twin needle – both needle threads must be the same type and thickness; use a ball point on knits.
- Hand sewing – for sewing on buttons and hems by hand, the thread can be thicker, and the needle is chosen according to the fabric.
- Embroidery – special embroidery needles with a larger eye are used, and threads with a different numbering.
- Shirring elastic in the bobbin – for shirring, the elastic thread is wound onto the bobbin by hand without tension, while ordinary sewing thread and a needle Nm 80–90 are used on top.
- Coated fabrics and membranes – choose the finest needle that will take the thread, to reduce the number and size of holes.
Where to find the right thread
For general sewing, browse the sewing threads; for linen and cotton products, the cotton threads; the full range is in the threads category. If you are unsure which size suits your fabric, ask for a sample.
Advice and samples from Polkom
Polkom is a Bulgarian manufacturer of accessories for fashion, furniture, footwear and bags, with large stocks of threads in various thicknesses and colours. Send us the type of fabric, machine and seam via the contact page – we will suggest a suitable thread and provide samples for testing before you order.
