Sewing Straight Seams
Machine Sewing Class
Lesson 4: Sewing Straight Seams
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Once you've started to get the hang of the basic operations of your sewing machine, the next step is to learn how to properly attach two pieces of fabric together by creating a seam. Seams are the basic method of attachment by which almost all sewing projects are created. In this lesson, we'll learn how to cut and pin fabric for sewing, sew a consistent distance from the edge of fabric, lock stitches, and press seams open with an iron when we're done sewing. The we'll use these skills to start creating a canvas grocery bag.

Fabric Grain

Before you start cutting and sewing fabric, there are a few things you need to know about fabric structure.

Woven fabric is created by weaving weft fibers through warp fibers that are stretched onto a loom. Because of the way this is done, the fabric ends up much longer in the warp direction. The warp fibers are also stronger than the weft fibers and usually run more consistently parallel to each other.

The warp fiber direction is called the grain and the weft fiber direction is called the crossgrain. On most fabric you can tell which direction is the grain because there is a strip called the selvage running along both grain edges. On quilting cotton the selvage is usually a white strip that has some numbers and writing printed in it, but on a lot of fabric it's just a strip with a slightly different weave than the rest of the fabric. The weave of the selvage creates a "self finished" edge which prevents the fabric from unraveling.

When you cut out pattern pieces, you need to orient them in a consistent direction in relation to the grain. Fabric that is woven with non-stretch fibers doesn't stretch along the grain but sometimes stretches slightly on the crossgrain, so you usually want long pattern pieces to be oriented parallel to the grain, or on grain, because that will make them the most stable.

Fabric cut at a 45 degree angle to the grain will stretch and deform quite a bit, even in non-stretch fabrics. Cutting fabric this way is called cutting on the bias, and is sometimes used to create fluid drape in dresses and other clothing. It is, however, much less common, and much harder to sew.

In this class we will mostly be cutting fabric on grain.

The Right and Wrong Side of Fabric

Most fabric also has a front and back. On some fabric, many printed fabrics for example, it is obvious which side is the "right side", (here it's the side where you can see all the owls :) on others it is a little more subtle. Of course, which surface you decide to show on the outside of your projects is always up to you, but you need to make sure are marking and sewing consistently on one side or the other.


Now let's learn how to sew a very basic straight seam. To do this we are going to cut two pieces of fabric exactly the same size, and the best way to do this is to cut them at the same time.

First, take a piece of your midweight practice fabric and press some of it with an iron on a setting appropriate to your fabric. Lay out your fabric on a cutting surface with the right side facing up. Fold the end of the fabric over on top of itself, lining up the selvage edges.

With your clear ruler and marking chalk or pen, draw a rectangle, about 4"x8" the put a couple of pins in the center of the rectangle.

With your fabric scissors, cut out your rectangle through both layers of fabric. As you cut, keep your scissors resting against the surface beneath your fabric and cut with long slow strokes. Long steady strokes will make your cuts smooth, whereas short choppy cuts can create jagged edges.

Now you have two pieces of fabric exactly the same size layered on top of each other with the right sides of the fabric together. You could, of course, also cut out the two pieces of fabric separately, but it's more exact and efficient to do it this way.

Marking and Seam Allowance

When you are connecting two pieces of fabric together with a seam, you need to leave a space between the edge of the fabric and the stitching line, this space is called a seam allowance.

Depending on what you are sewing, seam allowances can be anywhere from 1/4" to 2". We are going to give our seam a 1" seam allowance.

To do this, use your clear ruler and disappearing pen to mark a line 1" in from the edge of your fabric.

You don't always have to mark sewing lines, and it's more important on curved seams than flat seams like this one. When you get more comfortable with sewing, you will stop doing it as frequently, but for now, it will be helpful.

To Pin or Not to Pin

When sewing a seam, it's often useful to hold your two pieces of fabric together with pins so the layers stay aligned as you sew. Depending on what kind of fabric you are sewing, and the shape of your seam, pining can be more or less important, but it's usually a good idea to pin when you're first learning how to sew.

To properly pin a seam for sewing, stick your pins in perpendicular to your sewing line with the heads of the pins facing out towards the edge of the fabric. This will let you sew over the pins if you have to, or make them easier to take out as your sew. Weave the pins in and out of the fabric so they are going under the sewing line you marked.

On a straight seam like this, you really don't need too many pins, about one every two inches will be enough.

Sewing a Seam

Now put your fabric into the machine so the needle will be starting about 1/4" in from the beginning of the fabric. On the right side of your needle plate, you should find a seam allowance guide with small lines and numbers that will help you sew straight, perfectly measured seams. Find the mark that indicates a one inch seam allowance (mine doesn't actually have one, so I put a piece of scotch tape on my needle plate as a marker for that distance), and line the edge of the fabric up with this.

Lower the presser foot, then begin sewing slowly. After you've sewn a couple of stitches, stop, press down on the backstitch lever, and sew back a few stitches to the beginning of the fabric. Try not to go back over the edge.

Then let go of the lever and sew forward again. Sewing backward and forward like this locks the stitches at the beginning of the seam so they won't come unraveled.

To give your seam an even 1" seam allowance, don't watch the needle, watch where the edge of the fabric lines up with the seam allowance guide on the needle plate. Of course, as you do this, be careful not to let your fingers go under the needle.

Most home machines can sew over pins, but I usually like to take them out as I go. It's fine to start and stop sewing to do this, but once you get into a rhythm, you will usually be able to take the pins out as your fabric is moving.

When you get to the end of the fabric, lock your stitches again like you did at the beginning. Pull out your fabric and cut your thread. Trim your hanging threads as close as possible to your fabric on both ends of your seam.

Take a look at your seam, did you manage to sew a straight line that is an even distance away from the edge of your fabric? Does your stitch tension look good? Grab the two pieces of fabric and tug them gently, in opposite directions. Does your stitching stay in place or start to unravel at the ends? If any of this is off, don't worry, just keep practicing until you get a strong, straight seam.

Pressing Seams Open

Ironing seams is one of the most important steps in sewing. Properly pressed seams can be the difference between projects that look beautifully hand made, and projects that look amateur.

After you sew a seam, take it to your ironing board and lay it on down with the layers spread apart and the seam allowance facing up. Make sure your iron is set to the right setting for your type of fabric.

Use your iron to press the seam flat like this:

Now pick up your seam and look at it. How is it looking? Do the two pieces of fabric meet in a nice neat line? If so, you've sewn your first seam!

Does your fabric have Star Wars technical plans and owls on it!?? If it does, we should be friends :)

As you can see more clearly on the printed fabric, by sewing your fabric together with the wrong sides facing out, you have now created a finished seam on the right side of your fabric with unfinished seam allowances on the wrong side. In the next lesson we'll talk about how and when you need to finish the edges of your seam allowances.


It doesn't matter here because you're just practicing, but what if you make a mistake when you're sewing a project??

Basically, it's all over, just throw away your sewing machine and quit now.

Just kidding! Don't worry, you can take out stitches pretty easily.

Just use your seam ripper (it's that little tool that looks like a tiny lobster claw, or some kind of scary implement from the dentist's office).

Wedge the sharp pointy end between your stitches like this and cut them with the little blade in the dip of the claw. Be careful not to cut through the fabric itself.

You can also remove stitches from one side of the seam, like this:

Sometimes, you can take out one stitch every inch or so and then the whole thing will pull apart. The backstitched ends take a little more fiddling to get out, but you can do it.


    "id": "quiz-1",
    "question": "The outside edges of a woven bolt of fabric along the grain are called?",
    "answers": [
            "title": "the selvage",
            "correct": true
            "title": "the gutter",
            "correct": false
            "title": "the ditch",
            "correct": false
    "correctNotice": "Well Done!",
    "incorrectNotice": "Try Again"
    "id": "quiz-2",
    "question": "Woven fabric stretches most along the:",
    "answers": [
            "title": "grain",
            "correct": false
            "title": "bias",
            "correct": true
            "title": "crossgrain",
            "correct": false
    "correctNotice": "Well Done!",
    "incorrectNotice": "Try Again"
    "id": "quiz-3",
    "question": "At the beginning and end of a seam you need to:",
    "answers": [
            "title": "zigzag",
            "correct": false
            "title": "baste",
            "correct": false
            "title": "backstitch",
            "correct": true
    "correctNotice": "Well Done!",
    "incorrectNotice": "Try Again"

Project: Start a Grocery Bag

To practice some simple straight seaming, we're going to start a making an easy cloth grocery bag. This is a really basic project but also a very useful and satisfying one that is easy to customize. Once you know how to make this bag, you'll probably want to make one in every color and fabric! In this lesson we'll cut out the bag and start sewing it together, and in the next lesson we'll finish it.

Gather your tools and materials and lets get started.


Test Your Fabric

Since the fabric you're going to be using here is a little thicker than what you were practicing with, cut a piece and test it on your machine. Try sewing two layers, even three layers, and see how it does. Adjust the tension if you need to.

If your machine seems like it's struggling at all, you might want to change to a heavier duty needle (also it will be good needle changing practice ;) but my machine did fine on this fabric with a regular needle.

Cut Out the Bag

Your grocery bag is going to be made out of just two pieces of fabric.

For the bag itself: cut a piece 36" long by 18" wide

For the pocket: cut a piece 8 1/2" wide x 11" long (or cut two if you want a pocket on both sides, you can also eliminate the pocket entirely if you like)

Press your fabric first, then lay it out on a flat surface with the right side facing up. Fold the fabric over on itself, and draw an 18"x18" square along the fold. (You could just cut this out as one, unfolded 18"x36" piece, but cutting it folded is a bit more efficient.)

Draw an 8 1/2" x 11" rectangle on the back side of your pocket fabric. I oriented my pocket piece with the long edge parallel to the stripes on my fabric because I wanted the stripes to be vertical on the bag.

Use your scissors to cut out both pieces of fabric along the the traced lines.

Finish the Top and Bottom of the Pocket

Before we attach the pocket to the bag, we have to finish the top and bottom edges so they don't fray. We are going to do this with a 1/2" wide double fold hem. The best way to do this is to press them into place before we sew.

To do this very precisely, let's use our ruler and marking tool to draw a line 1" in from the edge of the bottom and top of the pocket, on the wrong side of the fabric.

Now take your fabric over to your ironing board and fold the edge of the fabric over so it just meets the line you drew. Press this fold with the iron.

Now fold one more time, so the raw edge is is hidden. The fabric should naturally want to bend at the edge of the first fold. Press again with the iron, creating a perfect 1/2" wide double fold. If you want, secure the hem with pins every few inches.

Repeat on the other side of the pocket.

Now go back to your sewing machine, and make sure that it is threaded with thread that matches your pocket fabric, or you can sew with contrasting thread like I am here. With your stitch length set to around 3, sew about 1/8" from the inner folded edge of the hem, being sure to lock your stitches on both ends.

Don't sew the hem on the other end of the pocket! We'll sew this down in the next step.

Sew on the Pocket

Use your ruler to find the center point on the bottom hem of your pocket and place a pin there.

Take the large folded piece of fabric that is the body of your bag. Use your fingers to press the fabric together at the folded corners, making little creases.

Remove the pins and unfold the fabric, you should still see these creases that mark the middle of the fabric on both sides. Mark each one with a pin or make a small mark with chalk or disappearing pen.

Position your pocket in the middle of the fabric, 4" up from these pin marks on one side, like this:

Making sure you're pocket stays square to the ruler, pin it down at the top and bottom. (If you want to put a pocket on both sides of your bag, pin another pocket on the other side of the center line.)

Take it to your sewing machine, and sew just the bottom of the pocket down 3/8" in from the edge of the pocket hem. Leave the top of the pocket pinned in place.

Pin on the Handles

If your webbing is a different color than the thread in your machine, re-thread the machine with a matching thread color.

Take your full 3 yards of cotton webbing and fold it in half on itself, making sure there are no twists. Match the two ends and hold them together with a couple of pins. Mark the opposite end of the loop of webbing with a pin.

Sew the ends of the webbing together about 1" in from the edge, locking your stitches.

Lay your bag fabric out again, with the pocket facing up. Now we are going to pin the webbing handles down to the bag so they are overlapping the sides of the pocket by 3/4". To get them lined up properly, use your ruler.

Take your loop of strap and lay it down on on top of your fabric, arranged so the seam and the opposite point you marked with a pin are both lined up with the center line fold point of the bag, and the webbing overlaps the edges of the pocket by 3/4".

The raw ends of the webbing should be facing down into the fabric.

Pin the straps down with pins every few inches making sure they are laying very straight. Place the last pin on each strap 2" down from the edge of the fabric

Sew on the Handles

To sew the black webbing down to the green fabric, you can use a little trick if you don't want the thread to show up on either side. Thread the top thread of the machine with black thread, but put green thread on the bobbin. This way the stitches on the bottom will be green, and the ones on top will be black.

Now sew the webbing down to the fabric by starting in the center of the fabric about 1/8" in from one edge of the webbing. Sew up one side of the webbing, stop at the last pin (2" down from the edge of the fabric) then turn, sew across the strap, turn again, sew back down, and keep going to repeat on the other side.

To make the turns, make sure you stop sewing and rotate your fabric with your needle down like we practiced in lesson 2.

Lock your stitches when you get back to where you started, then take your fabric out and snip your threads.

Repeat this same process to sew down the other side of the webbing loop.

Pin and Sew the Bag

Now we are going to sew the side seams of the bag together.

Fold the whole thing over at the middle fold point so the straps and pocket are on the inside.

Match the sides the fabric and the top edges to each other, and pin the side seams together. If you want, you can mark a 1/2" seam allowance line on the side seams where you are going to sew, or you can just use the stitch guides on your needle plate.

With your sewing machine loaded with thread that matches your fabric, sew the two side seams, locking your stitches at both ends.

What's Next?

That's it for now! In the next lesson we'll learn different techniques for finishing seams and creating hems and then we'll use some of those techniques to finish the grocery bag.


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