How to Sew a French Seam
French seams are a classic sewing technique that create an elegant finish on lightweight and sheer fabrics. They are basically enclosed seams on the inside of your project or garment—a bit like a double folded hem, but then a seam :-). On the wrong side of the fabric you will not see any frayed edges, just an enclosed fabric strip. On the right side of the fabric it looks like a regular seam, not showing any stitches. In the images below I’m showing you the wrong side of the fabric or how it will look on the inside of your garment or other sewing project.
French seams are easy to sew, but do require a bit of extra time and care. Unlike regular seams that leave raw edges exposed, French seams enclose the raw edges of the fabric within the seam, creating a neat and tidy finish on both sides of the fabric. This makes them a popular choice for delicate garments like blouses, dresses, and lingerie. They are perfect for creating a professional-looking finish. If you don't own a serger, using a French seam can be a good technique for you to master.
If you are looking for other ways to finish the raw fabric edges on fabrics with a sewing machine, we have another tutorial about this subject: how to finish edges with an overlock foot on a regular sewing machine. If you're looking to take your sewing skills to the next level, I suggest you give French seams a try. It is a technique that is great to have up your sleeve.
A French seam is created by first sewing a narrow seam with the wrong sides of the fabric facing each other. The fabric is then folded along the seam so that the right sides of the fabric are facing each other, encasing the raw edges of the fabric inside the fold. A second seam is sewn close to the folded edge, enclosing the raw edges within the seam. The result is a seam that is fully enclosed, with no raw edges visible. I’ll explain how to sew a French Seam step-by-step with clear images further down in this blog.
Why Is it Called a French Seam?
The French seam is thought to have originated in France during the 16th century, when the country was known for its fine tailoring and dressmaking. At the time, French seamstresses used this technique extensively in their work to create a clean and elegant finish to their garments.
Over time, the French seam became popular in other countries, and its name became widely recognized and used to describe this specific type of seam. The term "French" was likely added to differentiate this technique from other types of seams and to associate it with the high-quality, refined style associated with French fashion.
Today, the French seam is still widely used in the fashion industry and in home sewing, and its name continues to reflect its origins in French dressmaking.
What Is the Difference Between a French Seam and a Flat Felled Seam?
Both flat felled seams and French seams are techniques used to finish seams in clothing construction, but they differ in both appearance and construction method. In this tutorial I’ll focus on French seams, but I am preparing another blog about flat felled seams. Keep an eye on this blog or subscribe to our mailing list to not miss out on any new tutorials.
A flat felled seam is a strong and durable seam commonly used in denim and workwear. It involves folding one edge of the fabric over the other, encasing the raw edge, and then sewing through all layers. The result is a flat seam on the right side of the fabric with two rows of stitching and one row on the wrong side. The first image shows the right side of the fabric. The second image shows the wrong side.
You can of course choose whether you want the two rows of stitching on the outside or just one row. That is entirely up to you!
The table below compares a French seam and a flat felled seam
|Flat Felled Seam
Lightweight, sheer fabrics and medium-weight fabrics
Type of seam
Delicate and elegant
Strong and durable
Enclosing the raw edges of the fabric within the seam by sewing the wrong sides of the fabric together, trimming the seam allowance and sewing the right sides together.
Folding one edge of the fabric over the other, encasing the raw edge and sewing through all layers.
A seam that is fully enclosed with a polished look on both sides of the fabric.
A flat seam on the right side of the fabric with 2 rows of stitching and 1 row of stitching on the wrong side of the fabric
How to Sew a French Seam Step-by-Step
As any new sewing technique, you need to practice before trying it out on your new sewing project. This isn’t different for learning how to sew a French seam. Practice makes perfect, right?
The Materials You Need to Sew A French Seam
7 Steps to Sew a French Seam
In the following example, I’m using a total seam allowance of ⅜ of an inch. I’ll explain the calculations for French seams in the next chapter below. Let’s first go over the main steps.
1. Place the two pieces of fabric that you want to join together, with their wrong sides facing each other. This is different from a normal seam where you put the right sides together. Pin or clip them together.
2. Sew a straight line along the edge of the fabric, using a small seam allowance of about 1/8 inch (0.3 cm).
3. Trim the seam allowance down with fabric scissors to remove any frayed or uneven edges. The narrower you trim, the narrower you can sew the seam.
4. Press the seam to one side, using a hot iron. This helps to set the stitches and make the fabric lie flat.
5. Fold the fabric along the seam, right sides of the fabric facing each other, encasing the raw edges inside the fold. Press the seam flat on the wrong side of the fabric. The first image below shows the right side, the second image the wrong side of the fabric.
6. Sew another straight line of stitching along the edge of the fabric, about ¼ inch (0.6 cm) away from the folded edge. You are sewing on the wrong side of the fabric. This will enclose the raw edges of the fabric inside the seam.
Make sure that the seam allowance is neatly tucked inside and doesn't peek out. In the image below, you can see how the frayed edge peeks out a little in between the seam.
If all went well, you will have a seam that looks like any other seam on the right side of the fabric and an enclosed seam on the inside, no frayed edges showing.
7. Press the seam flat again, using a hot iron.
And that's it! You now have a French seam that hopefully looks polished like my seam.
How to Calculate the Seam Allowance for a French Seam
Let’s explain how much seam allowance you need for a French seam. Because a French seam has 2 rows of stitches, this is a little more complicated than a regular seam. Both rows of stitches will be hidden in the seam, you won’t see any stitches. The first row of stitches is on the inside of the fabric to hide the raw edges, the second row is the one that is sewn where a regular seam is sewn.
When you have a commercial pattern with a set seam allowance, make sure you don’t stitch that first row with that seam allowance. Let me give you an example:
If you have ⅜ of an inch seam allowance on your pattern, you will have to sew your first row somewhere between ⅛ and ¼ of an inch. The narrower the seam allowance for this first row, the better. Always trim the raw edges down as narrow as you can. The wider these edges are the more risk that they will be peeking out. This is what you need to avoid. The second row will be stitched at ¼” from the first row.
In theory, you can do your first row at 1/8”, trim the raw edges a bit, sew the second row again at ⅛”, sewing at ¼ inch of the original hem. In practice you need a little extra. If you only have ¼ inch seam allowance on your pattern, I wouldn’t recommend using a french seam. But, maybe you are a very accurate sewist and this is a piece of cake.
Two Disadvantages of French Seams
- A French seam isn't fixed flat. It has movement and can be pushed to either side of the actual seam line. This can be a pain when ironing, as you may see the imprint of the seam on the right side of the garment. In that sense it is more visible than other seams.
- A French seam is almost impossible on thicker fabrics because there is too much bulk within the enclosed seam.
Tips for Sewing with Sheer Fabrics
As French seams are mainly used with sheer, lightweight fabrics, here are some extra tips to get better results when sewing with this category of fabrics.
- When starting a row of stitches, lightweight fabrics are often pushed into your throat plate. To avoid this, place a piece of paper under the fabric, sew, and tear it away when done.
- Avoid backstitching. Instead, pull the thread ends to the right side of the fabric and enclose them with the raw edges in step 6.
- Use a smaller sewing machine needle, size 70 or 75
- Consider using stabilizer on the inside if your fabric is really hard to work with.
- Use clips instead of pins to avoid making holes in delicate fabrics.
And that’s about all there is to know about making French seams. If you have any questions at all, don’t hesitate to get in touch. I’m happy to help and make your sewing life easier and more fun!
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