Manufacturer · Fashion & Home Accessories
The right upholstery thread thickness depends on the type of seam: around Tex 40–70 for light textile seams, Tex 70–90 for structural seams on leather and seats, and Tex 135–210 for visible decorative stitching. The needle must grow with the thread – roughly from Nm 100–110 for Tex 40 to Nm 160–200 for Tex 210.
How upholstery thread thickness is designated
In upholstery you will come across several systems at once, which is often confusing:
- Tex – grams per 1000 metres of thread. A higher number is a thicker thread. This is the clearest system and we recommend comparing by it.
- V number (American system for bonded threads) – for example V69, V92, V138, V207. The number is very close to Tex, so V69 corresponds roughly to Tex 70 and V138 to Tex 135.
- Ticket number – a trade designation in which a smaller number means a thicker thread. Ticket 40 is finer than ticket 20.
- Denier – used to describe synthetic filaments, for example 210D/3.
When comparing threads from different suppliers, convert everything to Tex. If the cone shows only a ticket number, ask the supplier for the Tex or the recommended needle size.
Upholstery thread thickness by seam type
| Thickness (Tex / V) | Approximate ticket | Typical application | Approximate needle (Nm) |
|---|---|---|---|
| Tex 40 / V46 | about 70–75 | light covers, linings, cushions | 100–110 |
| Tex 70 / V69 | about 40 | joining seams on furniture and seats | 110–125 |
| Tex 90 / V92 | about 30 | leather, vinyl, piping, load-bearing seams | 125–140 |
| Tex 135 / V138 | about 20 | single and double decorative stitching | 140–160 |
| Tex 210 / V207 | about 13–15 | bold decorative stitching, straps | 160–200 |
The values are approximate. Every thread and needle manufacturer gives its own recommendations, and the final combination is confirmed with a test seam.
Why the needle matters so much
With every stitch the thread passes back and forth through the needle eye several times before it is tightened. If the eye is narrow, the thread rubs, heats up and its coating wears off. The result is a frayed or broken thread, skipped stitches and loops on the reverse. Along the length of the needle there is also a long groove into which the thread must fit completely while the needle pierces the material. With too small a needle the thread stays outside the groove and rubs against the material.
Conversely, too large a needle leaves holes that are visible – especially in leather and vinyl, which do not close up after piercing. In faux leather such holes act like perforation and the material can tear along the seam line.
Needle point for different materials
Cutting-point needles for leather
The point is sharpened like a small blade and cuts the leather rather than pushing it apart. Different shapes (angled, diamond, triangular) give different seam looks – the stitches lie straight or at an angle. For decorative stitching on leather seats the choice of point is part of the design.
Round-point needles
For upholstery textiles, Alcantara and acrylic fabrics. The point pushes the yarns apart without cutting them, and the seam stays strong.
Needles for vinyl
For vinyl and faux leather, needles with a light cutting point or a sharp point are often used. Cutting needles with too short a stitch length can weaken the material, so the stitch is lengthened.
Thread thickness and stitch length
Thread thickness and stitch length are linked. A thick thread with a short stitch looks crowded, the stitches overlap and the material is densely perforated and weakened. A thin thread with too long a stitch looks sparse and snags. As a guide: for structural seams with Tex 70–90, stitches of about 3–4 mm are used, and for decorative seams with Tex 135–210 about 4–6 mm. With leather and vinyl it is better to stay at the upper end.
Needle and bobbin thread
In decorative seams the needle thread is the thick, visible thread. The bobbin thread can be one or two steps finer, for example Tex 135 on top and Tex 90 underneath. This fits more thread in the bobbin, makes the seam lighter and makes tension balance easier to set. Both threads should be of the same material.
Signs that the thickness does not match the needle
- The thread frays just above the needle.
- There is a characteristic "popping" sound on penetration and skipped stitches.
- Loops form on the reverse side.
- A large hole remains in the leather around each stitch, or the edge splits.
- The needle thread breaks after a few centimetres of sewing.
A practical order of choice
- Determine the seam type – structural or decorative.
- Choose the thread thickness from the chart.
- Choose the needle by thickness and the point by material.
- Set the stitch length – a thicker thread needs a longer stitch.
- Do a test seam on the actual material stack and check both sides.
You will find suitable threads in various thicknesses in our threads for the automotive industry group. For leather goods such as bags, belts and shoes see our threads for footwear and leather, and for finer seams our sewing threads.
Samples and advice from Polkom
Polkom is a Bulgarian manufacturer and wholesaler of sewing accessories with over 30 years of experience. We help with choosing thread thickness and needle, match colours to a sample and send samples so you can try the combination on your machines. Minimum quantities depend on the article. Send us an inquiry via our contact page.
