Too Much Math
 

Right now I'm trying to figure out if I have enough fabric for a 2.5" bias binding. The quilt top is 64" square, so 64" X 4 is 256", plus two handwidths (16") for the final join and seams comes to 272".
The fabric I want to use has been cut into for border pieces so now the entire length of fabric is 31" wide, not the usual 44". That means my charts for binding requirements are out as well as the formula for dividing total binding inches by 11. These are all calculated on a 44" width fabric, right?
So now, I fold the fabric on a 45 degree angle and measure the length of that bias fold. It is 44". I have about 20 inches to go on the length of fabric which will yield 8 lengths of bias. 8 X 2.5"=20" (Plus the fabric triangles at each end that can be cobbled together if more is needed.) So I think I should get 352" of bias before seaming it together. 8 X 44" =352"
Does this sound right???
I've gotten myself all tangled up in the math sooo many times it's not even funny, I'd hate to whack up this beautiful deep purple fabric only to find I've miscalculated and come up short of what I need. Can anyone help with this or share a better way of figuring it out?

Math is not something I could help a horse fly with! When in doubt, when making a quilt, I ere to the larger point. Rather a larger quilt than one that comes out a little shy of what I wanted. When I lay a top on the floor if it doesn't look large enough I make it larger.

Sounds to me like the first paragraph is the length you need. 272" after it is all sewn together for the length. I don't know why you would want more than that.

I generally fake it until I make it and I always make too much binding. Better too much than not enough!

Here's a calculator that might help. It seems pretty easy and you already know all the measurements, it will let you put in the non-standard width.
http://www.quiltersparadiseesc.com/C...Calculator.php

What are the dimensions of the piece of fabric you have available for the binding?


The theoretical formula for figuring out if one has "enough" fabric:

Area of binding (length x width) needs to be less than area of fabric available (length x width).


Area of binding = width of binding x length of binding : 2.5 x 272 = 680 square inches

Area of fabric available = width of fabric x length of fabric : 31 inches x ______________?

680 divided by 31 = 21.94 inches. (Which would not be quite enough - in my experience.)


Remember to allow for "waste" - what is too small for the intended use and fabric "disappearance" - I am not sure where it goes, but if I am trying to get ten 3-inch cuts out of a 30 inch piece of fabric - I will only be able to get nine cuts.

I have the Robert Kaufman "Quilter's Little Helper" on my phone and use it frequently for quilty calculations. Math and I have never been friends. I would recommend it if you can get it. (It is free)

Just plugged in your measurements : Robert Kaufman says you need 266 inches of binding. This includes 10 inches "margin". Calls for a 30 inch square of fabric to make your bias binding.

Or you could just use Bear's formula! I am impressed!

wow, i've just been adding all four sides up and adding a bit maybe one more strip.

Wow!! Thank you! I had no idea there was an online calculator Iceblossom. According to that I have plenty. I forgot to include that my 31" wide piece is 51" long.
And thank you bearisgray, thats a good way to double check the math. I need ways to double check my math. Boy o boy do I need to double check the math. Instead of adding apples and oranges I could be including the pickles and end up way off track.
No cell phone service here suern3, but that's so impressive to be able to figure out right in the fabric store. We're short on fabric stores here, too, BTW.
The quilter's paradise page is bookmarked and theoretical formula duly noted in my notebook of important stuff.:thumbup:

If your quilt is square shape without curves, you don't need bias binding.

I have the same app as Sue and got the same calculations for bias binding.

Wow, all of that is too much math!

I never do bias binding. It wastes so much fabric. I cut across the WOF. I use my tape measure and measure how many 40" cuts I will need to make it all the way around my quilt. I add a foot or so for the mitered corners and bias seams. It usually comes out about right that way, with just a bit left over.

I just guess by the size of the unfinished quilt. For smallish sizes usually 6 strips WOF. No math needed.

Ah!!! bias binding. sorry. not my field. although i've done it a bit. Glad you got it all figured out.

Thank you again for the replies, and especially for the helpful answers.
However, I always strive to do my best work which includes following Sharon Schamber's advice with a folded and starched bias binding glued in place. I'm not interested in a straight edge binding. The question here was about a calculation for an odd size piece of fabric.

I prefer bias binding. I know it uses more fabric. BTW the binding will last longer if it is cut on the bias.

Thank God for all you math lovers! Really, truly it's good to know you enjoy it and can help those of who can only take so many numbers before we're in therapy.

You do not have to cut it on the bias if you are doing straight edges (most quilt bindings). Obviously if you are doing a scallop, bias is prefered. So the basic calculation is # of inches needed divided by WOF (272 by 31 = 9 strips). # of strips x's width of strips (9 x 2.5 = 23 ") To accommodate seams, I would buy 3/4 yard (actually knowing me, I would buy a yard -LOL).. If you want to do an actual bias, just use the table for 44" wide fabric, fold and cut continuous. This is a whole lot easier than driving yourself crazy trying to figure the correct amount. I would probably add about a 1/3 more of what they asked for because of the difference of 44" wide and 31" wide

You can find a can find a chart and calculations here:

https://thesewingloftblog.com/calcul...ntinuous-bias/

Thank you! I feel the same way about numbers! :-)

Does your binding need to be bias? If not, regular binding is easy to figure out.

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I found a quilting calculator online at "Quilter's Paradise". It is a free calculator to use online. This is what I came up with for your size quilt: [TABLE]
<tbody>[TR]
[TD="colspan: 3, align: center"]"Regular" Binding Calculations

[/TD]
[/TR]
[TR]
[TD][TABLE]
<tbody>[TR]
[TD="align: left"]Total binding length (inches) = 266
[TABLE]
<tbody>[TR]
[TD="align: left"]Number of strips to cut =10
[TABLE]
<tbody>[TR]
[TD="align: left"]Binding Yardage = [/TD]
[TD="align: center"]3/4 yards[/TD]
[/TR]
</tbody>[/TABLE]
[/TD]
[TD="align: center"]

[/TD]
[/TR]
</tbody>[/TABLE]
[/TD]
[/TR]
</tbody>[/TABLE]
[/TD]
[TD][/TD]
[TD="align: center"]
[/TD]
[/TR]
</tbody>[/TABLE]
I seldom do bias binding, but when I do, I use the online calculator for that, also. If you are making bias binding, you will need a 30" square according to the calculator.

I use this - www.mywebquilter.com
go to Calculators.

Basic math does have its uses.