Fabric Question for a math whiz
 

I have a quilt pattern that doesn't give rotary cutting instructions. It just says how many squares and strips to cut. EX: 70 strips @ 2 x 3 1/2, 70 strip @ 2 x 5 1/2, 28 strip @ 2x12, etc.

I know they can be rotary cut, but for the life of me I can't figure out how to calculate how many strips I'd need to cut.

Hoping someone will help me out. Soooooo....

If a quilt patterns says to cut 28 2x12-inch strips and my material is 44 inches wide...how many strips do I cut?

What is the formula for calculating that.

Sorry to be such a dummy. :( I have a Master's degree but it wasn't in math. LOL

Stuck here.

TIA,
Dray

Usually we cut fabric WOF (width-of-fabric), which is from one selvedge to the other (your WOF is 44 inches). So, you would be cutting 2-inch strips WOF. If the fabric is 44 inches wide, you can get only three 12-inch strips from the width-of-fabric. The rest is scrap. This calculation would be:
X*12 = 48
X= 48/12
X=3

You need 28 2x12-inch strips and you can get 3 per WOF. 28/3 = 9.33 so you would need 10 strips WOF to get 28 2x12-inch strips. (You would need only one 2x12-inch strip from that last WOF.)

Gosh, I didn't realize it would look so confusing when I started this! Hope it helps some.

It's simple division. 44 divided by 12, or 44 divided by 2, whichever fits best. 12 does not go evenly into 44, you will have quite a chunk of fabric left over. 44 divided by 2 is 22, you can cut 22 strips that are 12 inches long. Then you will need to cut 6 more strips to equal 28.

Hope this helps.

eta: whoops Prism beat me to it, although she took a different route, lol.

Thanks :) This had my head spinning.

Dray

if you cut your widest measurement first---such as 12" wide strip---then from that cut your smaller measurement (like 2") you will find it easier to figure out-
remember you need to remove salvages so, you will not have 44" of usable fabric.

so- 70 pieces that are 2" X 3 1/2" you would start with cutting 3 1/2" strips- you can then cut (20- 21) 2" cuts from each strip- you need 70...so 3 strips gives you 60-63, cut a 4th strip in half if you want for 7-10 more pieces.

70 @ 5 1/2" you do the same way- cut your strips 5 1/2" wide (if you start with the widest needed then you can use 1/2 of the 4th strip for your extra (10) 5 1/2" pieces and the other half of it for the 3 1/2" pieces

and the 28 12" x 2" you would cut 2 strips 12"...(20) 2" pieces from one---you only need 8 from the second strip---again you could use the other half of the strip to cut some of the smaller pieces if you start with the widest strips needed & work your way down....good way to (stretch) your fabric. always start with the largest pieces you need & work your way down

[QUOTE=Prism99;5898546]Usually we cut fabric WOF (width-of-fabric), which is from one selvedge to the other (your WOF is 44 inches). So, you would be cutting 2-inch strips WOF. If the fabric is 44 inches wide, you can get only three 12-inch strips from the width-of-fabric. The rest is scrap. This calculation would be:
X*12 = 48
X= 48/12
X=3

You need 28 2x12-inch strips and you can get 3 per WOF. 28/3 = 9.33 so you would need 10 strips WOF to get 28 2x12-inch strips. (You would need only one 2x12-inch strip from that last WOF.)
QUOTE]

actually, using this formula, x = 4 (48 divided by 12 is 4)

[QUOTE=rush88888;5899128]Yikes! It is supposed to be 44, not 48. And I should have mentioned to drop any remainder and use only the whole number.

Get yourself a cup of coffee and a caluclator and look at this again. It's a whole lot easier than you are trying to make it.

Use your calculator. Your fabric is about 42" of usable fabric (doesn't count the selvages) Divide 42 by the length of your NEEDED piece. So for the 12 inch pieces you'd get 3.5 strips that are 12 inches long. Use 3 and the half one which would be 6" lay aside for something else.

IN 25 words or less, anything to the right of the decimal point will go into your scrap pile.

I'm going to do Tula Pink's stacks. One of the required pieces needs to be 18.5" long. So I'd divide 42 by 18.5 (and without a calculator) I know I'll get two strips (total 37" which is less than the 42" WOF. With a calculator the exact number is 2.2702 strips.......................... Which would leave a scrap of about 5".

If you are using standard sized fabric ie. 42-44" this method will work NO MATTER HOW WIDE THE PIECE IS, as long as you are cutting WOF. You'd calculate a 2" x 12" piece the same way you'd calculate a 6" x 12" piece or a 12" x 12" piece.

Not to be bossy or anything--------cause I can be------but print this out and put in on the front page of your pattern folder.

Now, wasn't that easy!

[QUOTE=rush88888;5899128]but our fabric is usually not 48" of usable cloth

And so, if she were to go buy fabric with these kind of directions, how much fabric would she need to buy? 10 strips x 2" = 20" of fabric, how much yardage is that? (This is where I struggle the most). I figured the next cut up from 1/2 of a yard, which is 5/8 of a yard?