Stitch length - the short, long, and in-between lengths of stitches, are a very important part of the machine sewing process. Most sewing machines have a stitch regulator and the stitch length is commonly measured in millimeters. Basic knowledge about how the stitch length can vary, and how understanding the way these small measurements affect your sewing, is a vital part of getting the best out of your sewing machine.
What is Stitch Length?
The stitch length is the distance from one needle entry point to the next. Your automated sewing machine will have a stitch regulator to show the stitch lengths ranging from very small to a longer stitch.
A small stitch allows many more stitches to fit into a measured space while longer stitches fit fewer stitches into a designated space. Another factor is short stitches are tighter and closer while longer stitches are looser. It is interesting to note that the feed dogs under the needle change to adjust the stitch length. They alter the amount of fabric that is pushed through the machine to create the next stitch.
Shorter stitches are used for sewing delicate fabrics and are good around corners and curves. Longer stitches are useful for basting and gathering because the tension is loose and the stitch runs over a larger portion of the fabric. Longer stitches cope better with thicker fabrics or multiple layers of fabric.
Whatever project you may have it is always best to test the stitch length on a scrap of fabric and check the tension. The sewing machine manual of your make and model of the machine should have a chart of stitch lengths and their best usage to guide your decision.
Stitch Length - Conversion Table
While the majority of machines have the stitch length listed in millimeters, occasionally you may need to convert those to stitches per inch if you are following an older sewing pattern. Here is a useful chart to help.
There are 25.4 mm per inch. The formula is >> 25.4/mm length = stitches per inch
I have rounded the spi figures.
|Stitch Length in MM||Stitches Per Inch|
Choosing Stitch Length
Here are some helpful guidelines for choosing the right stitch length. These guidelines are based on the fabric used, the purpose of the stitches and the thickness of the thread,
1. Type of Fabric
- Light & Sheer - A shorter stitch length is best for lightweight and sheer fabrics. Silk, chiffon and chartreuse fall into this category. The best stitch length is 1.5 – 2mm.
- Medium weight fabrics use the standard stitch length of 2.0 – 2.5mm
- Heavy weight fabrics and quilts, or anything needing layers of fabric sewn together, need a longer length stitch of 3.0 – 4.0mm
- Leather and vinyl need longer stitches of 3.0 to 4.0 because the holes made by the needle can spoil the fabric if they are too close together.
2. Purpose of the Stitch
- Basting will require a long stitch. The longest stitch length 5mm or up to 7mm on some machines is best because a bigger stitch is easy to remove.
- Top stitching and decorative stitches a use a longer stitch, 2.5 – 3.5 and this size depends on the fabric.
- Machine gathering uses a longer stitch at 4.0 – 5mm
- Paper piercing needs a very small stitch length approx 1.3 – 1.6mm
- Quilting uses a medium stitch at 2.5 – 3.5mm while free motion quilting does not need a stitch length because the feed dogs are dropped and the quilt free to move in any direction.
3. Thickness of the Thread
- Thicker threads need a longer stitch of 3.0- 4.0mm.
- Thinner threads like silk need a shorter stitch of 2.5-3.5mm.
- Metallic and rayon threads use a longer stitch of 3.0- 4.0mm..
- Invisible threads called mono filament threads use a shorter stitch length pf 2.5-3.5mm.
Stitch Length Terms
Terminology and techniques can affect the stitch length you choose. Always consult your sewing machine manual and if necessary take a list of questions along to your sewing machine agent who may be giving free lessons and demonstrations with a new model of machine.
Here are some terms you may find in your patterns and how to relate them to your sewing machine’s stitch length.
Standard Stitch Length
This is the basic straight stitch used by every sewing machine for normal seams and joining two pieces of fabric together. This is your regular stitch for everyday sewing. The basic straight stitch may change to suit different weights and types of fabric but is commonly 2.5 - 3.0mm.
Topstitching is a decorative stitch sewn parallel to seam lines or the edges of collars and cuffs. It can outline a feature of the garment or strengthen a seam in a decorative way. Topstitching uses a longer stitch but the added length will depend on the fabric weight and the thickness of the seam or area to be topstitched. Topstitching varies from 2.0 to 4.0mm. Thicker threads should be sewn in a 4.0 length.
Stay stitching is a very useful line of stitching used to stop fabric stretching after the pattern pieces have been cut. The stay stitching around a neckline for example helps the neckline to hold firm before the facing is stitched in place. A shorter-length stitch of 2.5 helps to keep the fabric in place.
Basting stitch is a temporary stitch and a longer stitch length enables the stitches to be removed easily when the basting or tacking has done its job. Regardless of the fabric, the basting stitch length is the longest on your machine. This is normally 4.0mm.
Gathering is a very useful technique for creating frills and ruffles and needs a longer stitch length. A double or triple row of long stitches running parallel and pulled up together makes the gathers stronger and more secure. On most machines, the gathering stitch will be 4.0 in length.
Sewing darts is a dressmaking technique that benefits from using different stitch lengths. Starting the dart with a normal stitch length and ending with a shorter stitch at the tip is a useful way of making the most of stitch lengths. A dart should not be back stitched at the tip. It is tied off at the end and the smaller stitches keep the tip firm and secure.
A shorter stitch length on sewing curves makes a smoother curve line. Pockets that are part of a seam such as those in pants or skirts, benefit from a smaller stitch because the pocket gets used often and a smaller stitch is less likely to come undone. Test a stitch length of 2.0-2.5mm.
Stitch Length and Zig-Zag
The stitch length can also be shortened or lengthened in zig-zag to produce different effects. These can be used independently or in conjunction with different widths of zig-zag.
- Short stitch lengths from 0.5-1mm are used for buttonholes and for applique.
- Longer stitch lengths from 2.0mm are used for finishing seams that would otherwise fray.
- Stitch lengths of 2.0-3.0 can be used to zig-zag elastic to the edges of swimwear and leotards.
- Even longer stitch lengths of 4.0 can be used as decorative stitching.
Stitch Length and Decorative Stitches
Most machines have set stitch lengths for their more decorative stitches but you may find that you are able to use variable lengths for some of them. Consult your sewing manual and see which ones have adjustable lengths.
Stitch Length - In Conclusion
Knowing more about the stitch length and the different purposes for shorter or longer stitches makes machine sewing more professional and more practical. Next time you hear the saying: ‘A stitch in time saves nine’ you can be thinking that - A stitch the right length, gives added strength!