Manufacturer · Fashion Accessories
Embroidery thread weight is chosen by the number printed on the spool, with a higher number meaning a finer thread. The standard for machine embroidery is No. 40 – it gives good coverage and detail for most logos. No. 60 is finer and is used for small text and fine detail, while No. 30 (and the heavier 12–20) is for dense, raised fills and a visible decorative effect.
How to read the embroidery thread number
The thread number comes from yarn count systems that measure how much length is contained in a unit of weight. The more metres there are in one gram, the finer the thread – which is why 60 is finer than 40. Other systems are used in parallel:
- Tex – weight in grams of 1000 m of thread. Here it is the other way round: a higher Tex = a thicker thread.
- Denier (den) – weight in grams of 9000 m, often written as 120D/2 (two plies of 120 denier).
- Commercial number (No., Nm, "weight") – the number you see on the spool label: 30, 40, 60.
Different manufacturers do not always calculate the number in the same way, so two "No. 40" threads from different brands may differ slightly in thickness. In series production it is wise to test a new thread on the same design before changing supplier.
Embroidery thread weight: comparison table
| Number | Approximate construction | Needle | Typical application |
|---|---|---|---|
| 12–20 | Very heavy | 100/16 and up | Decorative stitching, hand-embroidery effect, fast fills |
| 30 | About 150D/2 | 80/12–90/14 | Dense logos, towelling, fleece, denim, fewer stitches |
| 40 | About 120D/2 | 75/11 | Standard: logos, lettering, emblems, patches |
| 60 | About 75D/2 | 65/9–70/10 | Text under 5 mm, fine lines, detailed designs |
The values are approximate and serve as a direction for choosing. The exact construction of a specific article is stated by the manufacturer.
No. 40: the standard
The vast majority of digitised designs in practice are prepared for No. 40 thread. The stitch density in the program (the spacing between fill rows) is calculated so that No. 40 thread covers the fabric without building up. So if you do not know which thread a file was made for, assume it is No. 40.
When to choose No. 60
- Small text. Letters under about 5 mm high lose legibility with No. 40 – the counters of "a", "e", "o" fill in. With No. 60 the letters stay clear.
- Fine detail in the logo. Thin lines, small symbols, complex crests.
- Thin fabrics. Shirts, blouses, fine jersey – a finer thread puts less strain on the fabric.
- Small labels and emblems.
Important: when switching from 40 to 60 the design must be adjusted – the density is increased, because a finer thread covers a smaller area. If you run the same file with No. 60 thread, the embroidery will look sparse and the fabric will show through.
When to choose No. 30 and heavier
- Towelling and plush – a heavier thread "sits" above the loops of the towelling.
- Fleece, denim, velvet – more expressive and three-dimensional embroidery.
- Faster production – fewer stitches for the same area.
- Hand-embroidery effect – heavy numbers 12–20 are used for visible decorative stitches.
Again the design density must be reduced, otherwise the embroidery becomes as stiff as cardboard and can buckle or tear the fabric.
No. 40 on different fabrics
On cotton T-shirts, polos and sweatshirts No. 40 works without adjustment. On piqué and rib it is wise to add an underlay so the stitches do not sink into the fabric structure. On caps with a stiff front panel No. 40 is also standard, but a longer satin stitch is sometimes used for a more raised look.
Bobbin thread weight
The bobbin thread is usually finer than the top thread – No. 60 to 90 or equivalent. It is not visible from the front and its only job is to lock the stitch. A finer bobbin thread makes the embroidery softer and allows more stitches per bobbin.
How thread weight affects the needle and the machine
The needle must match the thread. If the eye is too small, the thread rubs, frays and breaks. If it is too large for a fine thread, the holes in the fabric are visible and the stitches are less even. The basic rule is: heavier thread – larger needle. When changing the weight, also check the tension – heavier threads usually require lower top tension.
A practical choice for a workshop
- Keep a full palette in No. 40 – with it you will fulfil most orders.
- Add No. 60 in the main colours (white, black, grey, navy) for small text.
- Order No. 30 as needed for towelling and fleece when you have a specific series.
- Record the thread number, needle and density on the job card – so you can repeat the result in the next series.
You will find threads in all the main weights in our embroidery threads category. Sewing thread weights are designated in a similar way – see sewing threads. If the embroidery is to be combined with woven labels, we can match common colours.
Advice from Polkom
Polkom is a Bulgarian manufacturer and wholesaler of sewing accessories with over 30 years of experience. We help embroidery workshops and brands choose the thread weight, needle and colours to suit the design and fabric, and we send samples. We deliver throughout the EU, and minimum quantities depend on the article. Send an inquiry via our Contact page.
