How To Choose Right Thread For Your Sewing Project

If you’ve ever dealt with a broken seam, skipped stitches, or fabric that puckers and immediately blamed your sewing machine, or worse, decided you’re just bad at sewing: I have some really good news - it’s probably not you. 

The root of almost every sewing headache comes down to a tiny, overlooked trio: the wrong thread, the wrong needle, or the wrong tension settings. But once you know a few simple rules, you’ll be able to easily avoid these mistakes.

In this article, I'll share a tip how to choose a right thread for your sewing project.

I’ve partnered with Mettler for this post - they've been manufacturing high quality threads for decades, so they know exactly what it takes to get flawless results.

Mettler SERACYCLE sewing thread, made from 100% recycled polyester

Let’s dive in:

HOW TO MATCH THREAD AND FABRIC

In the majority of sewing projects, all-purpose thread is great - it’s a true MVP for your standard, medium-weight fabrics like cottons and linens. But the second you step outside that middle ground into super lightweight or heavy weight fabrics, all-purpose isn't going to cut it and you have to choose thread strength that correlates with the weight to your fabric.

Here’s a simple rule to remember:

The thread should never be stronger than the fabric.

If your thread is way stronger than a delicate fabric, the fabric becomes the weakest link. Under any kind of stress, the thread won’t budge - instead, it will literally slice through and tear your fabric to pieces. And your project is ruined.

On the opposite end: if you use a fine, weaker thread on a heavy canvas or denim, the thread is going to snap or wear out almost instantly.

So, lightweight fabric gets fine thread. Heavyweight fabric gets thick, strong thread. 

But how do you actually know which one is which when you're looking at a spool? If you’re using Mettler threads, at the bottom of each spool, you’ll see a little number next to the word 'No.' that indicates the thread strength - the higher the number, the finer the thread.

Mettler Bobbinete, No. 150 is very lightweight thread

For example, polyester thread marked 150 (like Mettler Bobbinete) is very thin and perfect for delicate fabrics.

Mettler Metrosene all-purpose thread, No. 100

All-purpose thread (like Mettler Metrosene) is marked with number 100 - just the right strength for your medium-weight fabrics and most sewing projects.

Mettler Extra Strong sewing thread, No. 36

Thread marked 36 (like Mettler Extra Strong) is very thick and strong, making it suitable for leather or denim.

No. 36 thread (top) vs No. 150 thread (bottom)

So next time, remember this cheat code: Big number, delicate fabric. Small number, heavy weight fabric. Keep that balance right, and your seams will actually last!

Enjoyed this tip? Here's a video with even more tips for better seams:

https://youtu.be/vuZATy_jZ2k

Thank you for reading and happy sewing!

Julija Gobere