The thread you use depends on your fabric weight and the look you want
Most home sewing machines work best with all-purpose polyester or cotton thread in weights labeled 40 or 50. These are the standard threads you'll find in any fabric or craft store, they cost between $1 and $3 per spool, and they work on light to medium fabrics like cotton, linen, and blends. If your machine came with thread, it was almost certainly all-purpose polyester in one of these weights.
The number on the spool—40, 50, or 60—tells you the thickness. Lower numbers mean thicker thread; higher numbers mean thinner thread. Weight 40 is the most forgiving for beginners because it's visible enough to see if something went wrong, and it works on almost everything from t-shirt fabric to home décor cotton. Weight 50 is slightly finer and gives a neater stitch on lighter fabrics. Weight 60 is thin enough that you'll only reach for it on delicate or sheer materials.
The fiber content matters less than people think. Polyester thread is stronger, doesn't fade, and handles heat better—it's the safer choice if you're unsure. Cotton thread looks slightly matte and feels traditional, but it can break more easily on older machines or when you're sewing thick seams. Many sewers use polyester for everyday projects and save cotton for heirloom work or when the thread will show on the finished piece.
Key Takeaways
- All-purpose polyester or cotton thread in weight 40 or 50 works on most home sewing machines and most fabrics you'll encounter.
- The weight number tells you thickness: 40 is thicker and more forgiving, 50 is standard, and 60 is for delicate fabrics.
- Polyester thread is stronger and more heat-resistant; cotton thread has a matte finish and is better for visible seams on finished garments.
- Specialty threads like metallic, variegated, or decorative require a larger needle and often a slower machine speed to avoid breaking.
- Cheap thread from dollar stores often sheds lint and breaks mid-seam; spending $2 to $3 per spool on quality thread saves frustration.
When to use specialty threads and what they need
Once you're comfortable with all-purpose thread, you may want to try specialty threads for decorative stitching or specific effects. Metallic thread adds shine but is stiff and breaks easily—it needs a larger needle (size 90 or 100), a slower machine speed (around 60 percent of normal), and often a metallic or topstitching needle designed to protect the thread as it passes through the needle eye. Variegated thread (multiple colors in one strand) works the same way as all-purpose thread but shows up better on solid fabrics.
Decorative threads like rayon or polyester embroidery thread are thinner and shinier than all-purpose thread and are meant for visible stitching on the outside of a garment. They also need a larger needle and slower speed. Invisible thread (monofilament) is thin enough to disappear into seams and is useful for hemming or attaching appliqués where you don't want the thread to show—but it can melt if your iron gets too hot, so test it on scrap fabric first.
Heavy-duty thread is thicker than all-purpose and is made for sewing canvas, denim, or leather. It requires a size 100 or 110 needle and a machine that can handle the extra tension. If your machine struggles with heavy-duty thread, it's a sign the needle is too small or the tension is set too tight.
How to match thread color and avoid common mistakes
The safest approach is to match thread color to your fabric, not your pattern pieces. If you're sewing a blue shirt from blue fabric, use blue thread even if the pattern calls for white. The thread will blend into the seams and won't show. If you're doing topstitching (decorative stitching on the outside), match the thread to the fabric so the stitches look intentional rather than like a mistake.
A common mistake is buying thread that's too cheap. Dollar-store thread and very old thread (more than five years in a hot closet) shed lint into your machine, clog the tension discs, and break mid-seam. You don't need expensive thread, but spending $2 to $3 per spool on a brand like Coats, Gutermann, or Mettler will save you hours of troubleshooting. Buy a small spool to test before committing to a full-size one.
Another mistake is using the same thread weight for everything. If you're sewing a heavy winter coat, weight 40 thread is appropriate. If you're sewing a silk blouse, weight 50 or 60 will give you a finer seam that won't pucker the delicate fabric. Puckering happens when thread is too thick for the fabric or when tension is too tight—switching to a thinner thread often fixes it without adjusting the machine.
Understanding thread weight numbers and what they mean
Thread weight is measured by a system where the number refers to how many strands of a standard thickness would equal one pound. This means the higher the number, the thinner the thread. It's the opposite of needle sizes, which confuses many beginners.
Weight 30 is thick and used for topstitching or heavy-duty work. Weight 40 is the most common all-purpose weight and works on most machines and fabrics. Weight 50 is slightly finer and is standard in many commercial sewing operations. Weight 60 and higher are thin threads for delicate fabrics or fine detail work. Most home sewers never need anything thinner than weight 50.
The label on the spool will say "40 wt" or "50 wt" or sometimes just "40" or "50". Some brands use different naming—Gutermann calls their standard thread "Mara 50" and their heavier thread "Mara 30". The number is always there; you just have to know where to look on the label.
Storing thread so it doesn't dry out or fade
Thread lasts longer when kept cool, dry, and out of direct sunlight. A sewing basket in a closet or drawer is ideal. Avoid storing thread in a hot car, a window sill, or anywhere it gets direct sun for hours at a time. Heat and light fade thread and make it brittle, which causes it to break during sewing.
Old thread—anything more than five years old—becomes dry and loses strength. If you inherited a sewing kit or found spools in a garage, test one on scrap fabric before using it on a project. If it breaks easily or sheds lint, replace it. New thread is cheap enough that it's not worth the frustration of a project that keeps coming apart.
Store thread upright in a box or on a thread rack so the spool doesn't roll around and get damaged. Keep the original label on the spool so you know the weight and fiber content later. If you remove the label, write the information on a piece of tape and stick it to the spool.
What happens when you use the wrong thread
Using thread that's too thick for your needle causes the thread to fray as it passes through the needle eye, which leads to breaking and skipped stitches. The machine may also make a loud grinding sound. The fix is to switch to a thinner thread or a larger needle.
Using thread that's too thin for the needle creates loose, uneven stitches because the thread has too much room to move inside the needle. The seam looks sloppy and may come apart under stress. Switch to a thicker thread or a smaller needle.
Using cheap or old thread that sheds lint clogs the tension discs and the bobbin area, which causes tension problems and skipped stitches. If you notice your machine suddenly making worse stitches after sewing with a new spool, the thread is probably shedding. Clean out the lint with a small brush and switch to a better-quality thread.
Frequently Asked Questions
Can I use the same thread in the bobbin as the top?
Yes, and most home sewers do. Use the same weight and fiber content in both the bobbin and the top thread. Some sewers use a lighter weight in the bobbin to reduce bulk, but this can cause tension problems. Stick with matching thread until you're comfortable adjusting tension.
What's the difference between polyester and cotton thread?
Polyester is stronger, doesn't fade, and handles heat better. Cotton has a matte finish and looks more traditional, but it can break more easily. For everyday sewing, polyester is more forgiving. For heirloom work or when the thread will show, cotton looks better.
Do I need to buy expensive thread brands?
No, but avoid the cheapest options. Mid-range brands like Coats, Gutermann, and Mettler cost $2 to $3 per spool and won't shed lint or break constantly. Expensive thread is usually for specialty work like embroidery. The difference between a $2 spool and a $10 spool is not worth it for basic sewing.
Can I use thread from a serger on my regular sewing machine?
Serger thread is thinner than all-purpose thread and is designed for the four-thread tension system of a serger. It can work on a regular machine, but it may cause tension problems because regular machines aren't built for such thin thread. Use all-purpose thread in your regular machine and serger thread only in a serger.
What should I do if my thread keeps breaking?
First, check that your needle is the right size for the thread and that it's inserted correctly. Then check that the thread is wound smoothly on the bobbin with no loose loops. Finally, clean lint from the tension discs with a small brush. If breaking continues, switch to a higher-quality thread or a thinner weight.