Choosing the right thread can feel confusing. Let’s clear that up and find out what weight thread for sewing machine projects you should use.
The thread weight is a number that tells you how thick the thread is. A lower number means a thicker, stronger thread. A higher number means a finer, thinner thread. Getting this right means your seams will be strong and your fabric will look great.
What Weight Thread For Sewing Machine
This is the core question. The “best” thread weight isn’t one-size-fits-all. It depends completely on your fabric and what your making. Think of it like choosing the right shoe—you need running shoes for a jog and boots for hiking.
Your machine will handle a range of weights beautifully if you match it correctly. Using thread that’s to thick for delicate fabric can cause puckering and damage. Using thread thats too fine for heavy fabric won’t be strong enough.
Understanding Thread Weight Numbers
You’ll see numbers like 40wt, 50wt, or 12wt on spools. This can be the most confusing part, so let’s break it down simply.
- Lower Weight Number = Thicker Thread: Examples are 12wt, 30wt. These are sturdy and visible.
- Higher Weight Number = Thinner Thread: Examples are 50wt, 60wt. These are fine and blend in.
The number comes from an old system based on length per weight. But all you really need to remember is the simple rule above. Most all-purpose sewing uses a medium-weight thread.
The Go-To All-Purpose Choice
For about 80% of your sewing, one weight will work perfectly.
- 40wt or 50wt Cotton or Polyester: This is the gold standard for general sewing. It’s strong yet fine enough for most woven fabrics like cotton, linen, and broadcloth.
- It’s great for garment construction, quilt piecing, and home decor projects.
- If you only buy one thread to start, make it a good quality 50wt polyester. It’s strong, has some stretch, and works on many fabrics.
Thread Weight Guide for Common Fabrics
Match your thread to your material. Here’s a quick-reference guide.
Lightweight & Delicate Fabrics
Think chiffon, silk, voile, or fine lingerie fabrics.
- Best Thread Weight: 60wt to 100wt.
- Why: A very fine thread won’t overwhelm the delicate fibers. It prevents puckering and visible holes.
- Type: Silk thread is ideal for natural fibers like silk. Fine polyester or cotton is also good.
Medium-Weight Fabrics
This is your everyday category: cotton, poplin, linen, rayon, and polyester blends.
- Best Thread Weight: 40wt to 50wt.
- Why: It provides the perfect balance of strength and discreteness. The seam will be durable without being bulky.
- Type: All-purpose polyester, cotton-wrapped polyester, or 100% cotton.
Heavyweight Fabrics
Denim, canvas, upholstery fabric, and corduroy fall here.
- Best Thread Weight: 30wt to 40wt.
- Why: You need a thicker, stronger thread to withstand the stress on these tough materials. It fills the needle hole properly for a secure seam.
- Type: Heavy-duty polyester or topstitching thread. You may need a heavier needle (like a 100/16).
Decorative Stitching & Topstitching
When you want the thread to be seen, like on jeans or decorative seams.
- Best Thread Weight: 12wt to 30wt.
- Why: Thicker thread creates a bold, visible line. It adds a professional, finished look.
- Tip: Use a topstitching needle, which has a larger eye to accommodate the thick thread. You might need to adjust your tension.
Step-by-Step: How to Choose Your Thread
Follow these simple steps for any new project.
- Identify Your Fabric: Feel it. Is it light, medium, or heavy? Check the care label if you’re unsure.
- Consider the Project: Is it a hidden seam (use finer thread) or decorative topstitching (use thicker thread)?
- Check Your Needle: Your needle size must match your thread weight. A fine 60wt thread needs a small needle (70/10). A thick 12wt thread needs a large needle (100/16).
- Test on a Scrap: Always sew a few lines on a fabric scrap first. Check for puckering, skipped stitches, or thread breaks. Adjust your needle or tension if needed.
Common Thread Types and Their Best Uses
Weight is crucial, but so is the material of the thread itself.
Polyester Thread
This is the most versatile synthetic thread.
- Pros: Strong, has slight stretch, resistant to mildew, and comes in many colors. It works well on both natural and synthetic fabrics.
- Best For: Almost everything, especially knit fabrics because it stretches with the seam.
100% Cotton Thread
A natural choice for natural fibers.
- Pros: It presses flat beautifully and blends into cotton fabric without sheen. It’s also heat-resistant.
- Best For: Quilting, sewing cotton garments, and projects where you want no synthetic shine. Be aware it has less give and can break down faster than polyester if exposed to elements.
Cotton-Wrapped Polyester
A hybrid that tries to offer the best of both worlds.
- Pros: A polyester core with cotton wrapped around it. It has the strength of polyester with the matte finish of cotton.
- Best For: Quilters often like it for its durability and flat press.
Silk Thread
A high-end, luxurious option.
- Pros: Incredibly strong for its fineness, very smooth, and blends into fine fabrics. It’s also elastic, making it excellent for basting.
- Best For: Sewing silk, wool, and other delicate natural fibers. Also perfect for hand-sewing buttons.
Troubleshooting Thread Problems
If your machine is acting up, the thread weight might be part of the problem.
- Frequent Breaks: Your thread might be too thick for the needle, causing friction and breakage. Try a heavier needle or a slightly finer thread.
- Puckered Seams: The thread could be to thick for the fabric. Switch to a finer thread weight (like moving from 40wt to 50wt).
- Skipped Stitches: This can happen if the thread is to fine for the needle and fabric combo, failing to form a proper loop. Try a smaller needle.
- Bulky Seams: Your thread is likely to heavy. This is common on lightweight fabrics. Go down a weight or two.
Remember, your machine’s manual is a great resource for recommended needle and thread sizes.
FAQ: Your Thread Questions Answered
Can I use hand-sewing thread in my machine?
No, you should avoid this. Hand-sewing thread is often waxed or treated and is not designed for the high speed of a machine. It can cause jams and tension issues.
What is the best all-around thread weight to buy first?
A good quality 50wt polyester thread is the most versatile starter spool. It will handle most of your basic sewing projects on medium-weight fabrics without any trouble.
Does thread weight affect my machine’s tension?
Yes, absolutly. Thicker thread (lower weight number) may require you to loosen the top tension slightly. Thinner thread might need a slightly tighter tension. Always test first.
Is it okay to use old thread?
Old thread, especially cotton, can become brittle and weak. It breaks easily and can leave lint in your machine. If it snaps easily when pulled, it’s time to replace it.
What’s the difference between embroidery thread and regular thread?
Embroidery thread (like rayon or polyester machine embroidery thread) is usually a 40wt but is designed to have a high sheen. It’s also processed to run smoothly at high speeds. You can use it for decorative stitching, but it may be to shiny for regular seams.
Final Tips for Success
Choosing the right thread gets easier with practice. Start by building a small collection of basic colors in a 50wt and a 40wt thread. Pay attention to quality—cheap thread creates more lint and causes more problems.
When in doubt, refer to this guide and do a test seam. Your projects will look more professional, and your sewing machine will run smoother when you match the thread weight to the job. Now you have the knowledge to confidently select the perfect thread for every fabric and project you take on.