The Best Seaming Guide: How to Sew a Seam

Learning how to sew a seam is essential for sewers. Seams join two parts together and the stitches of the seam should always lie on the markings for the seam line. Rows of basting stitches to keep the seam in place should be sewn on the seam allowance close to the seam line.

How to Sew a Seam with Different Techniques

Being able to sew seams is important. You should always know how to sew a seam. Below is an A-Z guide on how to sew seams with various techniques that covers everything that is essential to get the perfect seam. To follow the below, we advise you to read our guide which covers the parts of a sewing machine and their functions if you starting out sewing.

How to Sew Straight Seams

Straight seams can sound complicated for beginners. We have simplified the process into short steps below to ensure you get the perfect seam with ease.

  1. Place the pieces of fabric one on top of the other with the edges level — almost always with the right sides together. You can provisionally join the pieces by pinning, with the pins about 10 cm apart and at right angles to the direction of the seam. You may sew the seam over the pins and remove them afterward. For beginners or for seams in awkward positions it is a good idea to pin the seam first and then baste close to the seam line just inside the seam allowance. In this case, take the pins out one at a time while you are basting.
  2. Place the work under the presser foot of the sewing machine. Lower the needle into the seam line marked on the fabric by turning the hand-wheel, and lower the presser foot. Sew three or four stitches, activate the reverse function of the machine and sew back to the beginning of the seam, close to these stitches on the seam-allowance side. Switch back to forward motion and sew over the reverse stitches, then continue along the stitching line to the end of the seam.
  3. Fasten off the end of the seam with reverse stitches in the same way as at the beginning, if possible on top of the previous stitches or just on the side of the seam allowance. This fastening off ensures that the seam will not come undone. It is also called locking. Lock the beginning and end of every seam.
  4. Remove the basting thread or pins and press along the seam line. This is very important as it makes the stitching ‘sink’ into the fabric. Only after that should you press the seam allowances open along the seam line or press both together to one side. Do not neaten the edges of the seam allowance with zigzag until after you have sewn the seam.
  5. Depending on whether the garment is to look casual or elegant, you can top-stitch the seams on the right side of the fabric, the width of the presser foot away from and/or close to one or both sides of the seam. Then press the rows of top-stitching.
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How to Sew an Outer Corner Seam

Outer corners are found on such things as cushion covers, shirt collars, revers, and cuffs.

  1. Place the fabric right sides together and sew the seam with a normal stitch length to within about 2.5 cm from the corner. To strengthen the corner, shorten the stitch length to 1.3–1.5 mm and sew right to the corner. (If you are sewing leather or artificial leather, keep to the normal stitch length as otherwise the material will have more perforations and will tear more easily.)
  2. Now lower the needle into the fabric, raise the presser foot and turn the work through 90 degrees. Then lower the foot again and stitch 2.5 cm of the seam. Then set the stitch length back to the original length.
  3. Trim away the fabric at the corner at an angle of 45 degrees up to 2 mm from the corner. Then press the seam before turning the material to the right side. Pull the corner into shape by sticking a pin in from the outside and gently pulling out the corner. Baste the edges and press again.

How to Sew an Inner Corner Seam

Inner corners are found in features such as square necklines. The principle is the same as for sewing outer corners.

  1. Place the fabric right sides together and sew the seam with a normal stitch length to within about 2.5 cm from the corner. Shorten the stitch length to 1.3–1.5 mm and sew right to the corner. Then lower the needle into the fabric, raise the presser foot and turn the work. Lower the foot again and sew a further 2.5 cm. Then reset the normal stitch length and continue sewing.
  2. Now clip the fabric at the corner diagonally to about 2 mm from the seam at an angle of about 45 degrees. Press the seam and turn the work along the seam. Pull the corner into shape, taking care to see that it lies flat and the seam allowances are not being pushed up against each other. Finish by pressing again.

How to Sew Curve Seams

It is essential to mark the stitching line with tailor’s chalk or a textile marker.

  1. Place the fabric right sides together. Set the stitch length a little shorter than usual at 1.5 mm and sew the seam. Sew slowly and turn the work evenly.
  2. Clip (make vertical cuts in) the seam allowance to within 2 mm from the seam. The number of clips and the distance between them will depend on the curve — the sharper the curve, the more clips will be needed. Press the seam, turn the work, baste the edges and press.
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Top Tips for Sewing the Perfect Seam

You have learned to sew a seam, now its time to find out some extra tips for sewing seams. Below you will find some of our top tips when sewing seams and when they should be used.


Top-Stitched Seams

This kind of stitching emphasizes the character of a garment; double rows of top-stitching look more casual, a seam with a single narrow row looks more elegant. Designer understatement is achieved when the seams are not top-stitched at all.

Top-Stitching at Different Distances

When top-stitching close to a seam or an edge, with the right side of the work uppermost stitch 1–2 mm from the seam or edge. You can guide the machine freehand or set the needle position as far as possible to the left and run the foot along the seam line. If the top-stitching is to be the width of the presser foot from the seam, guide the edge of the foot along the seam or edge. If you want one row at each distance, always sew the row closest to the seam first.

Top-Stitching a Seam Open

Press open the seam allowances and, on the right side of the work, stitch the underlying seam allowance in place on both sides of the seam, close to it or the width of the foot away.

Fancy Top-Stitching

On national costumes or ethnic fashions, seams are often emphasized with decorative stitching. Threads in contrasting colors emphasize this style even more. When top-stitching on both sides, press the seam allowances open; for top-stitching on one side only, press both seam allowances to one side. Choose one or more fancy stitches with complementary patterns and sew them next to one another on the right side of the work. This will automatically hold the seam allowances in place.

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