Sewing Machine

How to Size Sewing Needles

How to size sewing needles

Many people use sewing skills to repair clothes, create designs, and even perform arts. But before you start sewing anything, you first need the right tools. 

When it comes to sewing machine needles, there are a few things that you need to consider:

  1. The type of fabric often determines the size of the needle.
  2. How thick the material is will determine how big the needle needs to be.
  3. How many stitches per inch (SPPI) you want to sew will also affect what size needle you need.

We explain how to measure your yarn and needles before getting started on your sewing tasks:

Use a smaller needle for thick fabrics. For example, if you want to sew with cotton fabric using a lightweight thread, you would use a size of 18 needle. You might need to use larger needle sizes if you’re using heavy thread and heavy fabrics.

To determine how many SPPI you need for your material, divide the number of stitches per inch by 2. if you want to sew with cotton and have an SPPI of 10 stitches per inch, your needle would need to be a size 16.

When in doubt about what size needle to use, always err on caution and use the larger needle. This way, you can ensure that the stitches will be tight and will not come loose.

Sewing machine needle
Sewing Machine Needle

What is the difference between a U.S. size and a British size?

Knowing the difference between U.S. and British sizes can be very helpful for sewing.

U.S. size refers to wide needles, while British size refers to long needles. So a U.S. size 1 needle is shorter than a U.K. size 1 needle.

Below are some possible uses for these sizes in sewing:

  • A US size 9 needle would be best for 18 inches or less in width fabrics.
  • A UK size 10 needle would be best for fabrics that are 25 inches or more in width.

There are other factors to consider when it comes to sizing, such as the type of fabric and the sewing technique you are using. 

But knowing the difference between U.S. and British sizes can be very helpful in understanding how your stitches will look on different types of fabric.

How to determine the correct size of sewing needles

Sewing machine needles come in various sizes, but what does that mean for you? To determine the correct size of your sewing needles, follow these simple tips.

First, measure the distance around your fabric that the needle should pass through without being too tight or loose.

Next, determine how many stitches per inch (SPI) you need your fabric to have. If you are using a cotton or knitted fabric, use 4 SPI. For your woven fabric, use 3 SPI.

Finally, match your fabric size to the appropriate sewing needle size. For example, if your fabric measures 18-1/2″ in circumference and needs 4 SPI to produce an even stitch pattern, use a size 10 knitting needle.

Remember to use the same needle for all your fabric layers, so your stitches go where you want them rather than out of place. 

Types of fabrics that need different sized needles

Three fabrics need different sized sewing machine needles:

  • Woven fabrics such as cotton, silk, and wool
  • Knitted fabrics such as cashmere, wool, and acrylic
  • Crocheted fabrics

To determine sewing machine needle size, first, measure the width of the fabric; it is usually around 3/8 inch or 9 millimeters for woven fabric. 

Knitted fabrics will be more complicated since they can be broader or narrower depending on the pattern. 

To determine the width of knit fabric, divide the width by the number of stitches per inch (2.5), giving you the stitch count in centimeters. Then, divide this stitch count by 12 to get the number of stitches per inch in inches.

For crocheted fabrics, measure in Centimeters. Most crochet patterns call for 18 to 24 stitches per 4 inches or 10 to 20 cm. So for an 18 cm wide crochet pattern, divide 18 by 4 to get 6 stitches per inch and divide this number by 10 to get 5 1/2 inches or 14 cm as your finished sewing machine needle sizes.

How to measure your fabric for needle size

Starting with the correct needle size is one of the most important steps in sewing. Not only does it determine how easily your fabric will take to sew, but also the stitches you create will be even and consistent. Follow these easy tips to determine your fabric’s recommended needle size.

To begin, measure the width of your fabric at its widest point. This measurement is called the “armhole depth”.

Next, divide this number by two to find the recommended needle size. For example, if your armhole depth is 6 inches, and you want a standard straight seam, use a US 8/5mm needle.

If you want a more fitted seam, or if your fabric is very thin or sheer, then use a smaller needle. Conversely, if you are using thicker fabrics or has more structure, use a larger needle.

Remember always consult the manufacturer’s instructions for specific care and sewing requirements for each type of fabric. Here are some tips for creating stitches that look perfect no matter what yarn you are using.

Tips for using larger or smaller needles

When it comes to sewing, you might be wondering how to size your sewing machine needles. Here are some tips to help you choose the correct size:

If you’re new to sewing, start with smaller sewing machine needles. They’re easier to handle, and you can get more done in a shorter time frame. As you get more experienced, try using large needles. They let you use minor thread, which means you will get smooth sewing.

Another thing to consider when sizing your sewing machine needles is the fabric you’re using. Some fabrics need a thicker sewing machine needle to avoid skipped stitches, while others will work best with a thinner sewing machine needle. Once again, experimentation is key!


Sewing machine needles generally come in different sizes, and these sizes help provide the necessary seam allowance. And with so many kinds of threads and notions, it’s challenging to determine what needle sizes are appropriate. 

This guide will help you choose the correct needle sizes. By following these simple steps, you’ll be able to find the right needle size for every project without any hassle. Thanks for reading!

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