Thread weight is thickness, and the number runs backwards: a 12-weight is thick, a 50-weight is the all-purpose middle, a 100-weight is nearly invisible. For piecing and everyday sewing use a 50-weight with an 80/12 needle; for quilting that shows, a 40-weight with a 90/14; for big-stitch hand quilting or bold decorative stitching, a 12- or 28-weight with a 100/16 topstitch needle; for appliqué and bobbins, a 60- to 80-weight. Then choose the fiber: long-staple cotton for quilting cotton and anything you want to press flat, polyester for garments and anything washed hard, trilobal polyester or rayon for embroidery sheen.
How weight is written
The common system is the “wt” number — 50 wt, 40 wt — which comes from an old length-per-weight standard, so a lower number means a thicker thread. Some makers add a ply number (50/2 is a 50-weight two-ply, 50/3 a three-ply and slightly stronger). Tex and denier are the industrial systems and run the other way (higher is thicker): a 50-weight is roughly Tex 30. Serger and industrial cones are often labeled in Tex.
Weight by job
| Weight | Needle | Use | Examples we carry |
|---|---|---|---|
| 80 wt | 60/8–70/10 | Bobbin, appliqué, English paper piecing | WonderFil DecoBob, Aurifil 80 |
| 60 wt | 70/10–75/11 | Bobbin, fine piecing, appliqué, binding | Superior Bottom Line, Mettler Seralene, Sulky PolyLite, Presencia 60 |
| 50 wt | 80/12 | Piecing, garment sewing, general — the standard | Mettler Silk-Finish 50, Aurifil 50, Superior MasterPiece, Presencia 50, Gutermann Natural Cotton, Metrosene, Sew-All |
| 40 wt | 90/14 | Machine quilting that shows, embroidery, topstitching | Superior King Tut, Signature 40, Mettler Silk-Finish 40, Isacord, Polysheen, Sulky Rayon, Aurifil 40 |
| 30 wt | 90/14–100/16 | Visible quilting, topstitching, sashiko-style | Sulky 30 Cotton and Blendables, Mettler Silk-Finish 28 |
| 28 wt | 100/16 topstitch | Hand quilting, bold machine quilting | Aurifil 28, Mettler 28 |
| 12 wt | 100/16–110/18 topstitch | Big-stitch hand quilting, bold decorative, redwork | Aurifil 12, Sulky 12 Cotton, Mettler 12, WonderFil Spagetti |
| Perle 8 / 5 / 3 | Hand needle (Chenille 20–24) | Hand embroidery, big-stitch quilting | Presencia Finca Perle, WonderFil Eleganza, DMC Perle |
Fiber by use
| Fiber | Character | Best for | Lines |
|---|---|---|---|
| Long-staple cotton | Matte, no stretch, presses flat, ages with cotton fabric | Quilting cotton, piecing, quilting | Mettler Silk-Finish, Aurifil Mako, Superior MasterPiece and King Tut, Presencia, Gutermann Natural Cotton, Signature, Sulky Cotton |
| Spun polyester | Strong, slight give, washes hard | Garments, bags, home décor, serging | Metrosene, Gutermann Sew-All, Coats Dual Duty XP, Maxi-Lock |
| Trilobal polyester | High sheen, strong, colorfast | Machine embroidery, decorative quilting | Isacord, Polysheen, Superior Magnifico, Exquisite, Glide, Robison-Anton Super Brite |
| Rayon | Highest sheen, less bleach-resistant | Machine embroidery on decorative pieces | Sulky Rayon, Robison-Anton Super Strength Rayon |
| Silk | Fine, strong, disappears into fabric | Hand appliqué, fine quilting | Superior Kimono Silk |
| Monofilament | Invisible | Stitch-in-the-ditch, invisible appliqué | Superior MonoPoly |
| Metallic | Metallic core or coating | Accents | Yenmet, Mettler Metallic, Robison-Anton J Metallic, Sulky Metallic |
Matching top and bobbin
The simplest tension setup is the same thread top and bottom. When the top thread is heavy — 40 and below — put a lighter thread in the bobbin (60-weight Bottom Line, 50-weight cotton, or a pre-wound) so the back stays flat and the bobbin lasts longer; loosen top tension a little if the bobbin thread shows on top. For embroidery, a 60- to 80-weight polyester bobbin thread is standard.
Spools, cones and put-ups
Spools of 100 to 500 yards suit a project on a domestic machine; cones of 1,000 to 6,000 yards suit a machine that runs all day and need a cone stand or thread holder on a domestic machine so the thread feeds straight up. Serger thread is sold on cones in matched sets of four. Boxed sets and color builders are the economical way to start a palette.
Reading a spool label
A label carries the weight (and often the ply), the length, the fiber and a color number. Length is the honest measure of value — a 164-yard spool and a 547-yard spool of the same thread look alike on the shelf. Color numbers are the maker’s own: Mettler, Aurifil and Isacord numbers do not cross-reference, so match by number within a brand or by eye between them. Where a label gives Tex rather than weight, divide roughly: Tex 30 is a 50-weight, Tex 40 a 40-weight, Tex 60 a 30-weight.
Thread for specific jobs
- Binding and hand finishing: 50-weight cotton or 60-weight polyester, matched to the binding color.
- Buttonholes: the same 50-weight as the garment, or a 30-weight for a bold buttonhole on coats.
- Topstitching on denim and bags: 30- or 40-weight polyester topstitch thread with a 100/16 topstitch needle and a 3.5 mm stitch.
- Serging: spun polyester cones — four matched cones for a four-thread overlock; textured nylon in the loopers for soft seams on knits.
- Free-motion quilting: 40- or 50-weight on top, 60-weight in the bobbin, a 90/14 quilting needle.
- Appliqué: 60- to 80-weight in a matching or invisible thread, 70/10 needle.
Shop the parts
- All thread — /shop/thread/
- Cotton thread — /shop/thread/cotton/
- Quilting thread — /shop/thread/quilting/
- Silk-Finish — /shop/thread/silk-finish/
- Needles by size — /shop/needles/
Frequently asked questions
Is a higher thread weight thicker?
No — lower is thicker. 12 wt is heavy, 50 wt is standard, 100 wt is very fine.
What weight thread for piecing a quilt?
50 wt cotton with an 80/12 needle.
Which thread for machine quilting?
40 wt if the quilting should show; 50 wt to blend; 60 wt in the bobbin.
Can I use embroidery thread for sewing seams?
It will hold, but it is a 40 wt sheen thread with little strength in seams; use a 50 wt polyester or cotton.
What is Tex?
An industrial thickness measure where a higher number is thicker — Tex 30 is roughly a 50 wt.
Which needle for 12-weight thread?
A 100/16 or 110/18 topstitch needle, and a longer stitch.
Cotton or polyester for a quilt?
Cotton for cotton fabric and a flat, traditional finish; polyester for strength and dense quilting. Both are used; cotton is the convention.