The Essential Guide to Sewing Seams

Sewing seams is basically using a stitch to join two pieces of fabric.

This is the basis of any sewing project. Learn how to do it in a clean and professional way.

Sewing seams is very easy, but there’s still some details that will make them look great.

From deciding the right seam allowance to pressing and finishing. Here’s the guide that will teach you everything about this important step.

Take your time to get this right and sewing will be very easy for you!


Before sewing, you must prepare your two pieces of fabric. Join their edges and pin them together. Hand baste and remove the pins.

How to Sew a Seam

You could sew on the machine without basting and remove the pins as you go. If you place the pins vertically, they glide under the machine’s foot and you don’t have to remove them.

BUT, If you don’t have much practice, your fabric will move. I’ve found that hand basting is the best way to prevent the fabric from sliding. I still do it for sewing seams on satins and pieces that are harder to handle.

Use a contrasting color to hand baste, this will make it easier to remove after sewing seams with the machine.


Every time you sew with your machine, you must start and end with a backstitch. This will prevent your seam from coming undone. Here’s how to do it:

  1. Sew about 1/4″ in a straight line
  2. Press your machine’s back button, don’t release it
  3. Sew another 1/4″, your machine will sew in the opposite direction
  4. Release the button
  5. Continue sewing

Practice a couple of times until you get the hang of it.

Sewing Straight Seams

A straight seam is just a straight line of stitching used to join two pieces of fabric. You can sew it by hand or using a sewing machine.

How to Sew a Seam

Sewing a straight line can be challenging without a guide. Mark the line you need to sew on the fabric and sew on top. This way you’ll be able to easily sew straight. You can also use the fabric’s edge as a guide.

A good exercise for practicing is to use a ruled sheet of paper. Go over each line without threading the machine. This will help you learn how to control it. When you can easily do it, move on to practicing with fabric.

Sewing Curved Seams

A curved seam is, as its name says, a curved line of stitching. Once you’ve mastered the straight stitch, move on to curves. This is a bit more challenging because you have to turn the fabric as you sew.

How to Sew a Seam

Always mark the stitching line on your fabric. Even if you’ve got some sewing experience, it’ll help you achieve a better curve.

Here’s a good exercise to practice curves. Draw a circle on a piece of fabric. Begin to sew on top of the circle. When you reach the point where you started, move your machine so that you sew another circle inside the original one.

Make sure that the edge of the machine’s foot is going along the line you already stitched. You will be drawing a spiral.

How to Sew a Seam

Sewing seams that are curvy is tricky. You may need to practice this a couple times before you get it right.

Seam Allowances

The seam allowance is the space left between a stitch and the fabric’s edge. You must add a seam allowance to anything you sew, if you sew on the fabric’s edge it’ll fray.

The size of the seam allowance can vary depending on what you’re sewing. 3/8″ works well for most things. For thick fabrics or ones that fray a lot 1/2″ would work better. In garments, you can leave a larger sized allowance to add room for fitting.

Leaving Seam Allowances

When pattern instructions tell you to leave a 1/2″ seam allowance, this means that you must leave 1/2″ between your stitch and the fabric’s edge.

You can guide yourself when sewing seam allowances in two ways. One of them is to mark the stitching line on your fabric. Then you sew on top of the mark. This is a tedious task, but sewing seams is easier this way if you have trouble controlling the machine.

Another way is to use your sewing machine as a guide. Most machines have seam guides marked on the throat plate. Measure the distance from the needle to each of the lines and determine the one you’ll be using. Mark it with a piece of tape.

When you sew, make sure the fabric’s edge is going along this line and you’ll get a perfect seam allowance.

How to Sew a Seam

Pressing Seams

After sewing, seams must be pressed to make them they fall in place. This is something that’s sometimes overlooked. But it’s very important. If you skip this step, your fabric will look bulgy on the front. There are two ways you can press your seams.

  • Flat Seams: open the seams towards the sides and press along the middle. I like to place a sheet of paper between the seam and the main fabric to protect it. Press the front too.
    How to Sew a Seam
  • Side seams: Fold both seams to either side and press.
    How to Sew a Seam

Seam Finishes

As we all know, fabric frays after being cut. To prevent it, we have to finish its edges!

Finish all the edges of each of your pieces right after cutting. If you sew first and finish once you’ve put everything together, the fabric will fray when you handle it. This will get things all messy. There are only a few cases when you should finish afterwards.

  • Serger

A serger is a machine specially designed for this purpose. As you sew along the edge of your fabric, it trims the fuzziness, giving you a perfectly finished piece.

  • Seam Binding

Seam binding offers a nice and elegant looking finish to your creations. It works great for delicate fabrics and it gives a nice appearance on the inside of garments. It also adds some strength to the seam.

After you’ve sewn a seam, clip the allowances so that they’re a bit larger than your binding. Encase them in the binding and topstitch.

How to Sew a Seam
How to Sew a Seam
  • French Seam

A french seam is also very useful to finish fabrics that fray a lot. It’s perfect for sheer garments because you achieve a clean finish on the inside. See the tutorial here.

  • Zig Zag Stitch

This is one of the easiest and most commonly used ways to finish a seam. It works well on most fabrics, except those that fray a lot. Finish all your pieces before sewing them together. This will make it easier to handle them.

Sew a zig zag stitch on the edge of your fabric. Always test the tension, stitch width and length before actually sewing. These settings can vary depending on the type of fabric and they’ll make a big difference in the final result.

How to Sew a Seam
  • Pinking

A pair of pinking shears is a tool any sewist must have. These will allow you to prevent the fraying on your fabrics in a snap. Use it for fabrics that won’t get too much handling. Pinking the edges of your fabric will prevent some of the fraying, but not all.

How to Sew a Seam

Watch step-by-step tutorials on zipper insertion, lining a skirt, adding darts, finishing with French seams and much more. Learn fit and finishing techniques with Sewing Studio, an online class, where you’ll learn methods you’ll use again and again.

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