Serger and overlocker Tension: A Complete Guide to Perfecting Your Serger Settings

Updated: Dec 6, 2021

When I first got my serger, it was magical! Gone were the days of finishing with a zigzag stitch, only to have the seams fray like crazy in the wash. No more did I have to use a French seam every time I wanted to sew fabric prone to fraying. Now I could finish all my seams fast, and even sew knit garments almost exclusively on my serger! However, while sergers are great tools that make many projects turn out better (and faster) – they don’t come without their frustrations.



Why is threading a serger/overlocker so important?

Threading can be a pain if you don’t have an air-threading machine and finding the right stitch settings for your fabric can be so challenging! When the tension is set correctly, a serged seam is a beautiful finish – but if the tension isn’t right, it can look like a real mess! If you’re having serger tension woes, below is a guide to help you troubleshoot your serger tension and find the perfect settings!




How to adjust your serger tension

Today we’re going to be focusing specifically on 4-thread serger machines because that is what most people have – but if you have a 3-thread machine, the process is very similar! Your serger should have 4 tension dials somewhere on the machine. Usually, they’re along the top of the machine in front of the thread spools, as in my Husqvarna Viking serger. However, some machines will have the dials on the front of the machine. These 4 dials are what control the tension on each thread – basically controlling how much of that thread is put into the seam over a certain time period. The higher the tension, the slower the thread moves through the machine.

Each of the 4 dials controls one of the threads – the left needle thread, the right needle thread, the upper looper thread, and the lower looper thread. Whenever you sew with a different type of fabric, you’ll need to sew a test seam on your serger and adjust the tension dials to the right combination for your fabric. I would highly recommend recording the settings that work for each type of fabric (maybe even with a swatch), so that in the future if you sew a similar type of fabric you have a good starting place for finding tension settings that work.



The perfect Serged Seam

Before we get into troubleshooting, it’s helpful to know what the “perfect” serged seam looks like. That way you know what you’re going for as you adjust the dials! In a perfectly balanced serger seam, the threads are taught to the fabric, but not tight enough to create puckering. Also, the “line” created by where the upper and lower looper threads meet up is right along the edge of the fabric.


Common Serger Tension Issues

Now let’s go through a few examples of some of the most common tension issues and how to fix them. Keep in mind that in the photos below all the fabric swatches are facing up – so the piece on top is the piece that was on top as it went through the serger.