100 Wt Thread: What It Is Used For, Needle Size and Brands
100 wt thread is ultra fine. It is used for micro-stippling and dense background quilting, invisible applique, heirloom machine quilting, with a 70/10 Topstitch (Superior MicroQuilter); 70/10 or 80/12 Microtex on domestic machines needle as a starting point. In the weight system, a higher number means finer thread: 100 wt means 100 kilometers of thread weigh 1 kilogram. Common examples include Superior MicroQuilter 100 wt and WonderFil InvisaFil 100 wt.
Thread weight (wt) is an inverse measure: the higher the number, the finer the thread. In the common weight system, the number is the kilometers of thread that weigh 1 kilogram. 40 wt means 40 km weighs 1 kg (Superior Threads).
| Thickness | Ultra fine |
|---|---|
| Common uses | Micro-stippling and dense background quilting, Invisible applique, Heirloom machine quilting |
| Machine needle | 70/10 Topstitch (Superior MicroQuilter); 70/10 or 80/12 Microtex on domestic machines |
| Example threads | Superior MicroQuilter 100 wt, WonderFil InvisaFil 100 wt |
| Next heavier | 80 wt |
| Notes | Usually polyester; strong despite its fineness. |
How does 100 wt compare with other thread weights?
| Weight | Thickness | Typical uses | Needle |
|---|---|---|---|
| 12 wt | Very heavy | Big-stitch hand quilting, Bold machine quilting, Decorative topstitching | 90/14 or 100/16 Topstitch (Aurifil 12 wt) |
| 28 wt | Heavy | Machine quilting with visible texture, Hand quilting, Blanket stitch applique | 90/14 Topstitch, Quilting, or Denim (Aurifil 28 wt) |
| 30 wt | Medium heavy | Decorative stitching, Quilting that should show, Some embroidery | 90/14 is a common starting point |
| 40 wt | Medium | Machine quilting with stitch definition, Machine embroidery (standard weight), Topstitching | 80/12 Microtex, Sharp, Universal, or Denim (Aurifil 40 wt); 90/14 Topstitch (Superior King Tut and Fantastico) |
| 50 wt | Fine | Piecing with flat seams, Garment sewing, Machine applique | 80/12 Microtex, Sharp, Universal, or Denim (Aurifil 50 wt); 90/14 Topstitch (Superior So Fine! 50) |
| 60 wt | Fine | Bobbin thread for embroidery and quilting, Fine piecing, Heirloom sewing | 90/14 Topstitch (Superior Bottom Line); 70/10 to 80/12 also used |
| 80 wt | Very fine | Invisible machine and hand applique, Heirloom sewing, Fine detail quilting | 70/10 or 80/12 Microtex, Sharp, or Embroidery (Aurifil 80 wt) |
| 100 wt | Ultra fine | Micro-stippling and dense background quilting, Invisible applique, Heirloom machine quilting | 70/10 Topstitch (Superior MicroQuilter); 70/10 or 80/12 Microtex on domestic machines |
Which needle size goes with each thread weight?
Match the needle to both the fabric and the thread. This Schmetz-based chart shows the thread weights usually paired with each needle size.
| Needle size | Thread weights | Typical fabrics |
|---|---|---|
| 60/8 | 80 to 100 wt | Silk chiffon, Organza, Batiste |
| 65/9 | 60 to 100 wt | Silk, Fine and highly elastic knits, Lingerie fabrics |
| 70/10 | 60 to 80 wt | Lawn, Voile, Silk |
| 75/11 | 50 to 60 wt; 40 wt embroidery thread on an Embroidery 75/11 | Lightweight to medium knits, Quilting cotton piecing, Machine embroidery |
| 80/12 | 40 to 50 wt | Quilting cotton, Shirting, Poplin |
| 90/14 | 28 to 40 wt; heavier threads on a Topstitch needle | Light to medium denim, Twill, Corduroy |
| 100/16 | 12 to 30 wt (use a Topstitch needle for 12 wt) | Heavy denim, Canvas, Upholstery |
| 110/18 | Heavy and topstitching threads | Heavy canvas, Upholstery, Heavy denim |
| 120/19 | Heavy thread | Very heavy canvas, Upholstery, Vinyl |
Test on a scrap first
Sew a few inches through the same layers as your project. If the top thread loops underneath or shreds, change the needle before touching tension.
Thread and machines for 100 wt work
Aurifil Perfect Box of Neutrals by Pat Sloan, 50wt
$136.99Aurifil 50 wt cotton in neutral shades, a favorite for piecing with a flat, accurate seam.
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Aurifil Classic Collection 50wt Thread Set
$189.86A wider Aurifil collection for matching thread to fabric.
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Janome HD9 Professional High-Speed Straight Stitch Machine
$1,599.00A precise straight-stitch machine that makes the most of fine piecing and quilting threads.
Check pricePrices change often, so confirm on Amazon. As an Amazon Associate we earn from qualifying purchases.
Frequently asked questions
What is 100 wt thread used for?
100 wt thread is used for micro-stippling and dense background quilting, invisible applique, heirloom machine quilting. It is described as ultra fine. Fine threads sink into the fabric, which suits invisible quilting, bobbins and dense designs where bulk would build up. Usually polyester; strong despite its fineness.
What needle should I use with 100 wt thread?
Start with a 70/10 Topstitch (Superior MicroQuilter); 70/10 or 80/12 Microtex on domestic machines needle for 100 wt thread. The needle eye must be large enough for the thread to pass without shredding, so heavier threads need bigger needles and topstitch needles with longer eyes. If the thread frays or breaks, move up one needle size before adjusting tension.
Is 100 wt thread thicker than 50 wt?
No. 100 wt is the finest thread in this chart. Thread weight is an inverse measure, so a higher number means thinner thread. Thread weight (wt) is an inverse measure: the higher the number, the finer the thread.
Can I use 100 wt thread in the bobbin?
Yes, 100 wt works in the bobbin on most machines. Many quilters match the bobbin weight to the top thread for balanced tension, while others choose a finer bobbin thread so more fits on the bobbin. Test on a scrap sandwich and adjust tension until neither thread shows on the wrong side.
What brands make 100 wt thread?
Examples of 100 wt thread include Superior MicroQuilter 100 wt, WonderFil InvisaFil 100 wt. Brands label weight differently: some use the weight system and others use cotton count, such as 50/2 on Aurifil spools. Aurifil labels cotton with the Ne (Number English) cotton count: the number of 840 yd hanks that weigh 1 lb.
How we research: we compare manufacturer specifications, owner manuals, published standards and recurring themes in verified owner reviews. We do not test products in person, and this is researched guidance, not professional advice. Follow your machine manual and pattern, and take care with rotary cutters, hot irons and needles. As an Amazon Associate we earn from qualifying purchases.