Thursday 16 October 2014

Decipher Your Quilt - Calculating Backings, Bindings and Borders

This week, Leanne of She Can Quilt and I will be talking about calculations for the three B's: backing fabric, binding and borders. It's a pretty lengthy post - and I haven't even touched on several things (like mitred borders and pieced borders), but if you would like us to cover anything we haven't already discussed, please let us know and we can add an extra post :o)

I apologise for this long and very wordy post, it was very difficult to come up with pictures for this one!


There are two main types of borders you'll come across in making quilts: straight borders (where you add borders to two opposite sides of the quilt, and then add borders to the other two sides) and mitred borders - where you mitre all four corners of the border. To keep this post from reaching epic proportions I'll just talk about straight borders today - but there is plenty of information available on the interwebs if you want to learn more about different types of borders. 

I don't often add borders to my quilts, but there are a few examples of where I've made quilts with borders so I've dotted those throughout this post to add a little bit of colour. Considering they are essentially just large rectangles, I think it's a bit surprising how much pain adding borders to your quilt can cause. The biggest problem that can happen is that your borders will end up wavy around the edges of the quilt - especially with very wide borders - but there are a few things you can do to stop this from happening.  

Measuring your quilt top to add borders is important - regardless of whether you're working from a pattern or designing your own quilt. I know when I make a quilt top it is very rarely square - partly from seams that probably aren't exactly 1/4" and partly because fabric does stretch a little when you handle it a lot. Each of the sides may not be exactly the same length because of these factors - but if you add borders that are the same length as the edges of your quilt top it will make any slight wonkiness in your quilt even more obvious. Even when working from a pattern, it is important to make the borders fit YOUR quilt, rather than assuming the pattern writer's lengths are correct. 

Measure your quilt top:

The most important thing is to measure your quilt top through the centre, rather than measure each of the edges. Some people take three measurements and then average these to get the most exact measurement - but I admit I usually just measure through the centre once. 

If your quilt is square, still measure the horizontal and vertical lengths separately, and make the borders to fit these measurements - you may find your quilt top isn't quite as square as you thought (I'm speaking from experience here!). 

Cut your border fabric:

When cutting fabric for your borders, there are a couple of things to keep in mind. 

1. Always cut your border fabric along the grain of the fabric - border strips that are cut slightly on the bias will stretch much more than those cut straight along the grain. You probably won't notice much of an issue with this, until you go to quilt your quilt - when you get quilting the borders, you may find you have excess fabric around the edges which can be a pain in the bum to quilt. It also makes it more difficult to square up your quilt after quilting. So it's important to make sure your ruler is following the grain when you start cutting strips. If you're cutting wide strips, you might even find you need to re-square up the edge a few times as you go. 

2. Cross-wise grain and length-wise grain have different stretch properties. Cross-wise grain (ie if you are cutting across the width of fabric, selvedge to selvedge like you normally would when cutting fabric for a quilt) has more stretch than length-wise grain (when you cut fabric parallel with the selvedge). 
You can use either type of cut for borders - but you may have to handle cross-wise cut border strips a bit more gently. Starch can really help prevent them from stretching too much. If your borders are really long, you may choose to cut length-wise border strips to avoid having a seam somewhere along your border strip. If you need to sew two pieces together to make a border, remember you will need to add 1/4" to both pieces to account for your seam allowance when they are joined. If you're worried about mucking this up, you could cut the strips a little longer than you think you'll need, and then trim the pieced border to size before attaching it to your quilt. 

3. Avoid cutting your border strips too long and then trimming them to fit the quilt top after you've sewn them - this is the best recipe for getting borders that don't fit properly and end up being warpy around the edges of your quilt.

So, choose which sides you want to add the border strips to, measure that length of the quilt top through the centre in that direction, and cut your border strips this length. 

When you go to sew these strips to your quilt top, it is a good idea to pin it well, to avoid it stretching as much as possible. This is the method I use for adding borders to a quilt:
  • Fold your border strip in half (lengthwise - so the two short ends are matched). Fold it a second time, and depending on how long it is, a third time. Finger press each of these folds. 
  • Do the same thing with your quilt top edges - find the centre point of the quilt top edge, and the points half way between the centre and the edges (and then the points half way between each of these if it is a particularly long border). 
  • Match up the folds on your border strip with the points you found along the edge of your quilt top. Pin each of these points - and then fill in the open areas with more pins. 
Once you've sewn the border on, repeat this process with the opposite side.

Then repeat the whole measuring through the centre (including the borders this time) and pinning process for the remaining two sides of your quilt top.


I think the easiest way to show you how I calculate how much backing fabric I'll need is to work through an example - so I'll work through what I'd do for a fictional 70" x 70" quilt top (my preferred quilt size to make and quilt).

You'll need to make your quilt back a bit bigger than the front - so the first thing to consider is how much overhang you want on your backing fabric. I like to have at least 4" on each side. So for our fictional quilt, the backing would need to be (70" + 4" + 4") x (70" + 4" + 4") = 78" x 78".

Most quilting fabric is around 42" - 43" wide - but when calculating backing requirements I like to round this down to 40". This means I don't need to worry too much about adding seam allowance to my measurements, and unless I'm making a really big quilt (over 80" wide) it will be a sufficient width.

So, if the backing required is 78" wide, I would need two widths of backing fabric (assuming it's 40" wide) to create a quilt back wide enough for the quilt top.

In terms of figuring out the length of fabric I'll need to buy, I divide the length required by 36" (the length of one yard). ie 78"/36" = 2.2 (rounded up). This is sufficient for one half of the quilt back, so I double that to get the total amount required - so here it would be 2.2 x 2 = 4.4 yards, which I'd round up to 4 1/2 yards.

I have to admit I've never made a quilt big enough to need more than two widths of fabric for the binding - but for something larger than about 82" on the shortest side, you would probably need three widths of fabric to make a wide enough backing.


Calculating how much fabric you'll need for binding isn't too tricky. There are just a couple of steps to figure it out:

1. Add together all four sides of your quilt top - so if we use the example quilt above it would be (70 x 4) = 280".
2. Add a bit extra to this number to give yourself extra binding fabric to join the ends together more easily. I add at least 12". So the example quilt would be 292"
3. Divide this number by 40 (roughly the width of fabric) to work out the number of strips of fabric you'll need. So the example quilt would be 292/40 = 7.3. So this would be rounded up to 8 strips of fabric.
4. Multiply the number of strips by the width you normally cut your fabric for binding - I cut my strips at 2.5" most of the time, so for the example quilt I'd figure 8 x 2.5 = 20" of fabric required for binding (so I'd probably buy 2/3 yard, or even 3/4 yard.)

A huge congratulations if you've gotten this far without falling asleep ;o) Leanne and I will be back for one final post in a few weeks time (on joining blocks different sizes together), but if there's anything we have forgotten and you'd like us to add, please let us know as we are happy to cover other topics later on this year.

xx Jess


Debbie said...

Yup, I made it to the end! ;-) Very good info here. Hope you don't mind if I share on my fb page. It's a good resource!

Unknown said...

A quick question.....I've added several borders by cutting them a bit long and then trimming and have always had success (not wavy). When I cut borders I am always careful to cut them on the straight of grain. May be that's why? I admit, I may have just gotten lucky. :-) Anyhow I'm just wondering why trimming afterward would make a border wavy. Thanks for the great series. I've learned lots!

Benta AtSLIKstitches said...

I never knew that fabric stretched more on the weft than the warp, so thanks for that. I think if this type of border as log cabin Or courthouse steps borders. Thanks for another fab post, I'm really looking forward to the different size blocks posts - those quilts always look fab but scary

Katy Cameron said...

Oh I'm super stingy with my backing then, I'm lucky if it's even 2" extra each side lol