Bias binding 101: How to make bias binding

Bias binding 101: How to make bias binding

Bias binding is one of my favourite things in sewing! It’s simple, functional and frequently beautiful. It has myriad uses and is both easy to make and sew. As it features in my brand new pattern, the Mariposa Bow-Back Dress, as well as in older designs such as the Piccadilly Pyjamas, the Fleet Top and the Bakerloo Blouse and Dress, I thought it was about time I gave you all my bias binding techniques and tips.

What is bias binding?

Bias binding is made from strips of fabric cut on the bias and then folded and pressed so the two raw edges meet in the middle. Its bias cut gives it a wonderful flexibility for going around curves and prevents it from fraying. 

What is bias binding used for?

It has two main uses in sewing. First, for binding the edges of seams – this could be for a decorative effect, showing on the outside. Alternatively it could be on the inside of a garment to protect seams from fraying or because the garment’s interior seams might be visible, e.g. in an unlined jacket. Bound interior seams are called Hong Kong seams. 

The Piccadilly Pyjamas use bias binding to finish most the garments' raw edges, highlighting the pattern's fun outlines.

The Mariposa Bow-Back Dress uses bias binding to finish the seams of the waist and sleeve armscye. One could alternatively overlock these edges, but not everyone has an overlocker and the binding offers a neater and stronger finish in an area that will be taking quite a lot of strain.

Secondly, bias binding can be very helpful in finishing curved seams – it acts as a kind of facing. It’s perfect for hemming circle skirts, for example, or for finishing necklines and armholes (as on the Fleet Top).

How bias binding is measured 

When a pattern specifies the need for bias binding, the width measurement given should reflect the folded width of the binding. This is the measurement given on the packaging when buying bias binding in the shops. So, for example an 18mm bias binding will measure 18mm when folded, but close to twice that if you unfold it. If you use it to bind a seam, it will be folded in half and end up measuring 9mm on each side.

Usually we use narrower bindings in dressmaking and wider bindings for the edges of quilts. For binding the visible edges of garments such as Piccadilly, I like to use binding that’s about 25mm wide, so the binding around the edges appears about 12mm deep. But in Mariposa, I prefer to use narrower binding such as 18mm or 12mm, as it is to finish interior seams, and I don’t want to increase bulk.

You can buy bias binding in pre-cut lengths in most sewing and craft shops, but it is often made with polycotton and the range of colours can be limited. For these reasons, I usually prefer to make my own. If you use a print it can be a really fun way to liven up the inside of a garment! 

How to make bias binding

Firstly, use non-stretch, woven fabric. Stable fabrics such as cotton are perfect, but you can also use slippery fabrics like silk if the project requires it. 

To find the bias, take a piece of fabric with sides on the straight grain and right-angled, i.e. a square or rectangle. Fold your piece diagonally to make a triangle, matching one straight edge to its neighbour. If your piece of fabric is square, you will be taking one corner over to its opposite. 

The long edge of the triangle you have created is on the bias grain. Gently press the triangle, taking care not to push or pull the fabric in any way as the bias can distort easily. Unfold the fabric and the pressed line shows you the bias grain. Mark along it; this will be the first cut edge of your binding. 

Then measure over how wide your unfolded binding will be (remember, if you want binding that is 2 cm wide when folded and 1 cm wide when bound around an edge, you will need to cut a piece 4 cm wide). If you’re working with cotton, I would simply use a pencil (or even pen – you’ll never see this edge once the binding is sewn) to mark the next cutting line; on more slippery fabrics chalk will be easier and more effective. 

Cut your strips. 

Trim each strip so they have straight ends. 

Top tip: A rotary cutter will be better than scissors at cutting your bias strips - you can run it along the side of a ruler to ensure you’re following your guides. 

Press your bias binding

You can get little tools specially designed for making bias binding. You feed the unpressed strip through the tool and it folds it for you, ready to be pressed as it comes out the other side. However, I own one of these and rarely use it. They only make one width of binding, and I personally find it just as easy to make the folds myself as to control the tool. It’s a personal preference, but don’t worry if you don’t have a tool – you definitely don’t need it!

To press the binding you need to fold the raw edges in so they meet in the middle, and then press them into place. 

Depending on how stable the fabric is, sometimes I do one side first, and then the other, and sometimes I just slowly and carefully use my fingers to fold in both sides at the same time. 

Note: Hong Kong seams usually only need one folded edge; the other is left flat. 

Top tip: whilst pressing your binding is key, avoid using steam in the iron as the steam can scald your fingers as they hold down the folds. 

Note how a 2-inch strip of fabric has turned into a 1-inch wide strip of bias binding.

Now your bias binding is ready to be used! Unless it's not long enough, that is... 

How to join two pieces of bias binding

Depending on the nature of the project and the size of your fabric to start with you may not need to join your lengths of bias binding together. (There is also a clever technique that allows you to cut much longer continuous strips of bias but that needs a whole other tutorial!)

If you do need to join two strips of bias binding, first, unfold them (don’t press). Lay the end of one bias piece over the end of the other piece, right sides together, at a right angle (imagine you’re creating a frame) and pin them together. The overlapping area between the two strips should be a perfect square. Three corners of the square are on the ‘outer’ sides of the ‘frame’ (marked in blue) and one is the inner corner (marked in yellow).

Draw a line between the two opposite outer corners of the square, as though you’re going to chop off the corner of the frame.

Stitch along this line, securing the two strips together.

Now, chop off the corner of the frame!

Press the seam allowance open gently, and then re-press the folds of your newly unified strip of bias binding.

Well, that's it – you've made bias binding! My next blog post will be all about how to use it. 

Back to blog

Leave a comment

Please note, comments need to be approved before they are published.