Welcome to the Ultimate Thread Guide, your one-stop resource for all things thread! Thread literally holds your sewing projects together, so it is important to make sure you pick the best type of thread for each project. This guide is essential for beginner sewists who are ready to start their first thread collection. If you have sewing experience, this information can help you make your sewing projects professional and flawless.

Image Credit: Sewing Mantra
Part One: How to Measure Thread Size
Congratulations! You’ve decided to embark on your first sewing project. You go to your local craft store and head straight for the spools of thread. However, as you peruse the shelves, your heart starts to sink. The thread is labeled with all kinds of confusing, cryptic numbers. 30 wt? V-46? 630d? These seemingly incomprehensible numbers and letters might leave you feeling overwhelmed and intimidated.
Never fear! Seams and Scissors is here. Read below to learn everything you need to know to pick the perfect thread size for your sewing projects. To learn about different thread content and materials, check out Part 2 of the Ultimate Thread Guide.
Thread size is measured in thickness, but the method of measurement often differs from brand to brand. The four most common ways to measure thread are listed below.
1. Weight: Weight measurement, designated as “wt”, uses a fixed weight system. The “weight” of the thread is actually a length measurement, determined by measuring the length of 1 gram of thread. The higher the weight number, the lighter the thread. For example, a thread labeled 60 wt. means that 60 meters of the thread weigh 1 gram. A 40 wt thread only takes 40 meters to weigh 1 gram, so it is heavier. This may seem confusing, but just remember: smaller weight number, heavier thread.
2. Denier: Denier measures weight in grams of of fixed length of 9000 meters of thread. For instance, if 9000 meters of thread weights 150 grams, it is called a 150-denier thread, or simply 150d. This is the opposite of the weight measurement method, so remember: bigger denier number = heavier thread.
3. Tex: Tex is the most widely used method of thread measurement. It uses a fixed length of 1000 meters of thread to determine weight. For example, if 1000 meters of thread weighs 20 grams, it is called tex 20. Tex is similar to denier, but will have smaller numbers. Just like denier, larger numbers mean heavier threads.

Image: Coats Cotton Covered Thread
4. Commercial Sizes: These are used for heavy-duty sewing, such as webbing or upholstery. They have set sizes of 30, 46, 69, 92, 138, 207, 277, 346, 415, and 554. These measurements are derived by dividing the thread’s denier by 10.
Is your head spinning? Don’t worry! We’ve included this handy conversion chart that you can consult wherever you are to make sure you know exactly what size of thread you are getting and compare each sizing method.
Weight | Denier | Tex | Commercial |
33 | 300 | 30 | V-30 |
22 | 460 | 45 | V-46 |
14 | 690 | 70 | V-69 |
11 | 920 | 90 | V-92 |
7 | 1380 | 135 | V-138 |
Now that you understand thread measurement, how do you know which size to choose? Here are some helpful tips to help you select the most appropriate size for your sewing projects.
- In general, the thread should match the fabric in size and weight. For heavier, thicker fabrics, use heavier thread
- Heavier threads create more visible stitches
- V-69 is the heaviest size recommended for sewing machines
- Heavier threads are stronger
- The eye of the needle should be 40% larger than the thickness of the thread
Click here for Part 2 of our Ultimate Thread Guide: Types of Thread Materials.
Do you have any thread measurement tips or suggestions?
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Where is “Click here for Part 2 of our Ultimate Thread Guide: Types of Thread Materials ” ? When I click the link it tells me that the page is no longer available. Very disappointed.
It worked fine for me xx
U can go back to the original site & link to #2 that way.
I always buy Dual Duty thread and I wonder why some of them have numbers and some of them have a letter and a number, ie,B1 or T12 or just 11. Can you help me understand the difference?
very informative
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How do you measure the diameter of thread ? Such as the tool for determine micron or nanometer thread?