stupid math question
 

I've decided to sew a bunch of leftover fabric to use as a backing for a quilt. If I have 12 inch blocks, they are really only 11 1/2 after they are sewn together, right? I'm just trying to figure out the easiest way to put all these things together to be the same size as the front. I HATE MATH!

Yes, if your square measures 12 inches unfinished, they will measure 11 1/2 inches when sewn together. You will actually want your back larger than the front when you layer the quilt.

We need to know how many blocks you have and if you intend to put in sashing before we can help with the size of the backing. if you have 12 inch blocks and putting 6 across would give you a width of 69.5 inches across.
(11.5 x 6 = 69 + .5 inch for the edge = 69.5.) To that I would add 6 inches = 75.5 inches which makes it easier to center the top on. Some people use less than 6 inches, and I have also, but prefer having the extra space.

You would do the same for the length as the width.

I never prepare the back until I have finished the quilt top, so I have the measurement of the actual top and not what I thought it would be.

You don't want to create too much additional bulk with your backing otherwise, when quilted, there may be some skipped stitches. You need to have the backing bigger otherwise it is almost impossible to line up the backing with the quilt top because the batting will be in the way.

To me, the totally math challenged quilter, all math questions are stupid...math is just plain stupid! LOL I know, I know, life as we know it couldn't exist without math! I am just numerically challenged! :D :D :D

Usually when people talk about 12" blocks they mean 12" finished size. 11.5" finished, (12"unfinished) would be very unusual.

My quilt top is 55 x 62. I'm just gonna start sewing blocks together for the back and see what I end up with! I've got 12 inch squares, 6 1/2 inch squares, random rectangles, etc. I'm trying to use up fabric. Thanks for your help. I'll be sure to make the back bigger.

I'm with you--there are no stupid questions, just stupid math! :)

If you are challenged with maths cut the blocks all the same size and join then even pins will so to the desired size. Measure if you feel brave . Or just lay another set out to match but back larger. It is easier to quilt if the back has a line of blocks and two large pieces of fabric . This reduces seams but gives a design on the back.

I am so glad to see others are mathematically challenged. I am always so embarrassed when i can't figure some things out. I always end up doing it the long way, the hard way or backwards :p I know i am no dummy and neither is anyone else here.

Why is math mixed up with something as enjoyable as quilting ;)

Ths is pretty much how I do it.

Carrie in PA - my son would LOVE your avatar! Teenagers and My Little Pony - I just don't get it, but there are a lot worse things for them to talk about!

When I got ready to read the responses to this post this morning, I was thinking that there were quite a few responses and wondering if most of the responses are from math geniuses or from people that are hoping for help figuring something out, like me. Regardless, I'm thankful for all the responses, and glad to know that I'm not the only one that doesn't understand why I have to do math if all I want to do is quilt!

When I first started quilting, I kept the math aspect of it at arm's length, but over time realized that the math for quilting is nothing harder than what we learned in grade school--definitely nothing to fear. The more you work with it, the easier it gets.

To figure out the size of your quilt back, measure your quilt top: 55" x 62"
Add 3" to the right side and 3" to the left side: 55" + 6" = 61"
Add 3" to the top and 3" to the bottom: 62" + 6" = 68"

61" x 68" is the size you need your quilt back to be.

To know how many 11.5" squares you need horizontally, divide 61" by 11.5" to get 5.3. Round down to 5.
To know how many 11.5" squares you need horizontally, divide 68" by 11.5" to get 5.9. Round up to 6.

5 squares in one direction multiplied by 6 squares in the other direction equals 30 squares--done!

If you draw out the blocks on 1/4" graphing paper, you can plan a pleasing layout for the blocks. use 1 block per inch and just show the finished size on the paper. Remember to add 1/4th inch on every side for seam allowance. (You probably won't believe me but truly the more often you use the math, the easier it will get) :p
Joyce in Delaware

You're so right Joyce, it does get easier but for some reason i always manage to forget one seem allowance somewhere.

Math is funny to me. I stink at it yet my older daughter is a whiz, she's taking all of the math classes in high school that i never made it to. My younger daughter unfortunately has my math genes and the way they do math now is nothing like what i was taught at her age. In fact, my older daughter wasn't taught the same way. Nothing is the same as when i went to school, they don't even teach handwriting or cursive anymore. Chicken scratch is apparently acceptable since everyone types now.

..and what will be worse, this untaught generation is unable to read cursive....although I think most are unable to read period! I was taught Palmer method of penmanship...now that dates me, but I am proud of my cursive writing and thank heaven for the patient nuns who taught us!

I believe that was the same way i was taught and i know it's how my mother was taught. I suppose it had everything to do with location and the school systems. When i was about 10 or 11 we moved from a large area to a rather rural area and some things aren't as important to some people i suppose. I love it here but unfortunately we are cut off from many things because of education and distance.

In the mean time, i teach my kids all i can about all the "old fashioned" arts that are slipping away. Cooking, canning, sewing, baking, etc. My youngest one is amazed at how i can make sausage gravy for biscuits faster from scratch than i can from a mix. It's an instant world!

Wow, way off topic. I will be quiet now lol

Yes and now we don't ''type' we keyboard.