Seamingly Badass

Learn to Sew: Make a Straight Seam

Alright, let’s get to the nitty-gritty – Making a seam.

I’ve seen the question “How do I learn to sew straight?”

Well, it takes practice. It’s like riding a bike or driving a car.

I mean when I first started driving, I managed to run my folk’s car parallel to (and uh… touching) a nice barbed-wire fence just outside our driveway cause I didn’t turn hard enough … I digress.

Basic Seam

Let’s talk about a basic seam.

In most cases, when making something, you’ll be sewing two pieces of fabric together.

Typically, we put right sides of the fabric (the part that you want to see on the outside of the garment) together. You can think of this as face to face.

You’ll see why in a bit.

When you sew, you have what is called the “stitch line” this is where you want the needle to go through the fabric.

And you have some additional fabric that will stay on the inside of the garment (or accessory). This is the seam allowance.

MOST of the time, when we sew, the seam allowance is to the right of the needle. If you look at your machine, you can see that it is set up to accommodate this. Seam allowances generally aren’t bigger than 1 inch. And so the bulk of whatever you will be sewing will be to the left of the machine, and the tiny bit of seam allowance has to fit on the “inside” of the machine between the needle and the body of the machine itself.

Additionally, if you look carefully at your needle plate area. Your machine probably has some markings at different intervals. These are typically at 3/8″, 1/2″, 5/8″, 3/4″, 7/8″ and 1″ (and maybe a little beyond). Yours might also have slightly off-line marks for metric millimeters (mm). A 1/4″ seam allowance is roughly 6mm.

Typical seam allowances found on patterns are: 1/4″, 1/2″ and 5/8″.


To sew a straight seam, you pin the two pieces of fabric together. With the faces of the fabric touching each other.

Place the fabric under the presser foot and line the edge of the fabric up with the mark associated with your desired seam allowance.

Place presser foot down using the lever, clamping the fabric between the presser foot and the feed dogs.

Don’t tug the fabric. The job of your hands is to maneuver the fabric side to side gently to keep the edge of the fabric on the correct line for the seam allowance.

As you press down the foot pedal, the feed dogs will do the work, pulling the fabric through the machine.

This is all well and good to talk/type about it. But let’s practice.

First. Get some super cheap fabric. I recommend a cheap woven fabric, like a cheap broadcloth or muslin. You just need about 1/2 -1 yard. (Depending on how much practice you want to do).

You’ll also need some thread. And it doesn’t need to match. In fact, maybe it’s better if it doesn’t. Then you can see where you went off line.

You’ll want to choose a needle. For something like a broadcloth or muslin, you’ll be fine with a standard (all-purpose) needle. Somewhere between sizes 10(70) and 14(90). One of the most common is the Size 12 (80).

The bigger the number, the bigger the needle.

The lighter weight the fabric, the smaller the needle necessary. (In general).

Cut your fabric in 2″ strips crosswise.

Practice sewing 1/2″ and 5/8″ seam allowances.

If you’re feeling really adventurous, you can try a 1/4″ seam allowance. Fair warning, my machine doesn’t have a 1/4″ seam allowance mark yours may not either. I have to line my fabric up on a specific spot on my presser foot. (So it would change if I have a different presser foot on my machine).

Here’s a video with step-by-step instructions and a little sew-along. 

As a “bonus” here’s a great technique to start practicing how to sew without pins. But more importantly, you can start learning to use your feed dogs to your advantage.