Bias strips make custom bias binding, as well as to finish the inside of a handmade fashion garment seams (and more!). Learn how to cut bias strips in these step-by-step how-to tutorials. First we have the basics of cutting on the bias, and if you need a lot of bias strip use the continuous bias strip method below.
What is a Bias Strip?
Let’s start with what is a bias strip. A bias strip is a piece of fabric cut at a predetermined width that is cut at a 45 degree angle to the straight of grain.
What’s straight of grain? Fabrics are made by tightly weaving threads in two directions called the warp and weft. The important part to remember is that the selvage, or bottom edge of the fabric that generally includes the fabric designer and manufacturer contains the warp threads and runs along the straight of grain. This is the lengthwise grain. Across the straight of grain, the warp threads woven from selvedge to selvedge make the width of the fabric or cross grain. Most quilters cottons are 45″ wide; upholstery fabric is generally 54″ wide.
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Woven fabrics on the straight of grain are generally not stretchy (unless they contain spandex or other stretchy materials). Quilting cotton fabrics generally don’t stretch.
Some applications are better when the fabric has a little give and stretch, and the shape is easier to manipulate. This is when a bias cut strip comes into play. For example, if you wanted to bind the edge of an oval placemat, you want the binding to smoothly go around the entire edge. If you used strips of fabric on the straight of grain, they wouldn’t lay nice and flat because the seams would create bulk. You can easily manipulate bias strips smoothly cover the edge with their offset seams.
How to Cut Bias Strips
Bias strips of fabric are used for many applications, including bias tape to edge garments, home dec and accessory items. They are also used in fashion sewing for Hong Kong finishes to seams.
Learn the basics of making bias strips.
Materials
- 1/2 - 1 yard of light weight woven fabric like quilters cotton
Tools
- Rotary cutter
- Quilters ruler
- Cutting mat
Instructions
- Start by laying your fabric out on a cutting mat with both selvedges lined up.
- Take your quilters ruler and find the line marked with the 45 degree angle. Line this up along the selvedge of your fabric.
- Using your ruler as a guide, using your rotary cutter, cut your fabric at the 45 degree angle. This will make the fabric edge be on the bias.
- I like to carefully turn that new cut edge of the fabric to be straight with my body to make the cuts for bias strips. Be very carefully to handle the fabric gently to keep the layers even and not to stretch the fabrics. Bias fabric stretches very easily. This is not when you want it to stretch. You want it to stretch when you are applying the strips in the application that you are using -- like adding a bias tape facing, or border to placemats.
- Making sure that the cut edge is straight, carefully place your quilters ruler and measure how wide you want to make your bias strips. Using your rotary cutter, make a cut.
- Continue cutting strips until you have enough bias strips for your project!
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How to Make Continuous Bias
Do you have a project that needs a lot of bias? Here is a quick method to make a continuous bias strip. It’s really easy, once you do it. 🙂
Start with a square of fabric. Then cut it in half diagonally.
Flip one side over, right sides together so that you are sewing the straight of grain.
Sew a 1/4″ seam allowance.
Press the seam open. It is important to press the seam open so there is less bulk in your finished product.
Here is what your piece looks like:
Now is the tricky part. 🙂 Fold the piece so that the straight-grain edges meet in the center, as shown below. This will form a tube with offset ends. The offset should match the measurement of your desired bias cut strips. The straight of grain edges are where you’ll sew the next seam (the edges that are together below). The outside edges are the bias of the fabric.
You can mark cutting lines on the back of your fabric, if you’d like, and line up the cutting lines as the start and end of the seam line. I just measure with my ruler. I cut a 2-1/4″ bias strip, so I move the ends to offset them by 2-1/4″ on both sides of my next seam line.
Carefully line up right sides together, measure again to make sure you have your measurements (which is why it might be easier to mark the cutting lines), and sew a 1/4″ seam. The tube will not lie flat on your sewing machine because you offset the edges – that’s okay – just keep the raw edges of your seam lined up as you stitch.
Now you have a tube! Press the seam open using a sleeve roll or wool seam presser.
Here is what your piece looks like now! Don’t press it flat, only the seams.
Now we are ready to cut! I take my handy-dandy 6-inch ruler and line it up and cut away! If you marked cutting lines before sewing, cut along those lines.
Keep turning your tube, measuring and cutting.
And, keep cutting until you have a long enough bias strip for your project. I usually cut it all and then have bias strips ready for another project!
My square made this finished pile of one long continuous bias cut fabric strip.
Need to know what size square to start from? It’s a pretty easy calculation. Take the starting size of your square of fabric and multiply it times two and divide by the width of your bias strip. Example: For a 1-1/2″ finished bias strip from an 18″ square: (18×18)/1.5=216. So an 18 inch square would make 216 inches of 1-1/2″ bias strip of fabric. Here is a handy continuous bias strip fabric calculator:
Learn how to use bias strips to make custom bias tape with two pins, double fold bias tape and use on handmade garments to finish seams with a Hong Kong finish.
