View Full Version : knitting math

11-03-2007, 08:28 PM
OK so help me figure this out:

If you have one skein of Malabrigo that is 216 yards long and you are knitting at 4 stitsches per inch and you want to knit a scarf that is 72 inches long, how many rows will you get if you cast on 200 sitiches? Is there a way to calculate such a thing? :??

11-03-2007, 08:44 PM
Maybe you can knit one row and measure it?

If a train going 98 mph leaves Seattle at 4:22 pm. . . .:??:teehee:

11-03-2007, 09:00 PM
If you are knitting it lengthwise, you need 288 sts to make it 72" long. 200 would make it 50" long. You will get 144 sts per yard or 31,104 sts per skein. Making roughly 108 rows for the 288 st length.

11-03-2007, 09:47 PM

Lady Violet
11-03-2007, 09:50 PM

11-03-2007, 09:52 PM
OK, you are getting 4 stitches to the inch, but how much yarn are those four stitches taking up? That's the missing factor in your equation. So time to swatch and then frog and measure. So you have 216 yards x 36 inches = 7776 inches per skein. 7776 inches / X inches (x being the amount of yarn in one stitch which may even be a fraction) = number of stitches you can get per skein. Take that number and divide it by 228 stitches to get your number of rows.

11-03-2007, 09:59 PM
:thud::passedout:How did she do that?

11-04-2007, 12:10 AM
okay, so are you knitting this scarf longways or shortways? because i made a big mistook in my gauge for my first big project, a baby blanket, and ended up knitting it lengthwise (45" wide and knitting until it was 36" long, as opposed to the reverse) which is very difficult to wrangle, which is why the shorter end is usually worked back and forth to a desired length.

do you have a row gauge? (this is the vertical measurement of how many rows per inch, for folks who haven't run into this term before.) does it differ significantly from the stitches per inch? this impacts how easily you can switch from knitting longways to shortways.

288 stitches cast on will give you a scarf 72 in long, at 4 sts/in.
how many inches wide would you like the scarf? and you want to know if 216 yards is enough to make it that wide?

is this in stockinette or a stitch pattern? because your gauge may differ if it is garter stitch, or cables that take more yarn...

the thing which makes you head spin until you sit down with paper and pencil is that the yards of unknit yarn listed on the ball band and inches of finished work in the spi aren't measuring the same thing, so a swatch needs to be made, marked, unraveled, and _CAREFULLY_ measured (no stretching!!!) to see how many yds of yarn are in how many inches of finished work. then, using that ratio of how many inches of yarn per stitch, you can figure out if you will have enough yardage to complete a number of rows so that a lengthwise scarf isn't too too skinny.

that's why longtail cast-on makes me mess up so many times, because you have to estimate how long a tail you need to cast-on the desired amount of stitches, and if you are _AHEM_ lazy and impatient, you don't know how long that is when you impetuously start casting on.

can somebody who is a knitting/spinning superstar speak up about Wraps per inch, and if malabrigo lists wpi on the ball band, and if wpi could be used to help calculate yardage needed here? cuz while i'm pretty good at word problems due to my H.S. chemistry teacher, i don't get wpi yet.

e, who hates math, can't calculate 15% gratuity in her head, but is drawn to word problems like a moth to flame

"ouch! OUCH! i'm singed!!"

p.s. the listing of yardage on the ball band may differ painfully from reality. i practiced some x-treme knitting recently and finished a hat with 3/4" of yarn to spare, even though i had gauge down pat, and the pattern said one ball would be enough. not to malign malabrigo, i don't know their reliability as a brand in having what's listed match reality, but there's no way without measuring to be absolutely certain the listed yardage is actually all there.

11-04-2007, 08:31 AM
It seems to me that you would just about have to knit a swatch in pattern to determine this. Assuming that the 4 stitches/inch is the row, there is nothing here to tell how many rows/inch and without that info it can't be calculated. A swatch would give the missing info.

11-04-2007, 08:47 AM
:think: shhhh...Don't tell anybody.. but, SOMETIMES MATH makes my head hurt.

11-04-2007, 10:55 AM
And I thought I wouldn't need algebra once I left school.

11-04-2007, 09:22 PM
:doh: I don't know why I started out on the right track..... but my mind must have slipped a gear to 4 sts per inch of yarn. :aww:

Knitncook is right, you'd need the amount of yarn it took to make those 4 sts to get the right number...... sorry. :eyes: My only excuse involves, wallyworld, my oldest dd, and being banned for life....

11-05-2007, 01:32 AM
Here's what I do: I weigh my wool, knit a repeat or two, measure the work, and weigh the remaining wool.

So I do 3 repeats of a scarf, and I now have 44 grams of the ball left, it was a 50 g ball so my 3 repeats have used 6g altogether.
So each repeat uses about 2g.
So my 50g ball will give me about 25 repeats.
If each repeat is 3.5 cm long, the length I get from a ball will be 25 x 3.5 = 87.5 cm.

You could do something similar, put a knot in the ball about 5-10 metres in, knit a certain amount, say up to the knot at 5m, whatever you have knitted is what you get from 5m of wool, simply multiply that area by the number of 5m lengths of wool you have for the item. You don't even need to unravel.

11-05-2007, 09:34 AM
Ok yeah I've been reading this thread and going :whoosh:for most of it, but this story?

My only excuse involves, wallyworld, my oldest dd, and being banned for life....

Yeah, we need to hear this one. :teehee:

11-05-2007, 03:21 PM
Sorry, I'll hi-jack temporarily, the punishment is worse than the deed though....
You know those displays of gift cards?? My dd (15) whose brain is usually in la-la land, thought that some of them were very pretty/cool and that if they weren't good for anything unless you put money on them or activated them at the check-out that they had no value so she took 3 and snapped the top part off..... Unknown to her was the fact that she was being followed by one of those "plain clothes" security people. I guess at some point, she layed them down to look at something and forgot about them. As we were leaving this security person stops us to ask dd what she had done with the cards. DD told her that she couldn't remember, that she thought they might be in the purse section. (The security girl looked like she was about 12 and there was a clashing of personalities. DD started out polite, but the girl smarted off about police and juvi, so dd gave what she got.) We were hauled back into the store to search for them and they were found, right where she thought they were. Then we were hauled to the back.. informed that it was considered shoplifting, and notified me that DD, in smarting off to the security person, had essentially, "resisted" authority so she was banned for life or until the age of 110. I offered to pay for the cards, (one was a $25 mastercard thing, the other 2 were regular gift cards) but I was informed that they had to be sent to the head office to be assessed a value.... which could be anywhere between $50 and $500. And that we would have to pay for whatever time this girl had put into following dd. I asked her if she was being paid for her job and when she said yes, I informed her that she sure wasn't going to get paid twice! Then after we'd signed the paper saying that we understood what dd was in trouble for, I made the comment that city, state and federal agencies expunged a juviniles (sp) record when they become an adult. Her answer.."We're not the government.... we're Wal-Mart." That's about it, except DH wanted to sue for emotional distress because the punishment was too harsh for the crime and he forbade me to ever go there again.
Sorry this is so long... again, sorry for hijacking!!

11-05-2007, 03:31 PM
Oh man! I don't mean to laugh; I hope it's a situation you laugh at as a family (for the draconian absurdity). I'm sorry you had to deal with that crap, but I'm glad you gave it right back. That story just about sums up my eternal frustration with all that is WalMart. :ick:

Thanks for sharing :hug:

11-05-2007, 04:21 PM
Wow.. Thats a crazy story. The punishment was way harsh. Technically, she didnt even steal them!

Yes, Thanks for sharing.

11-06-2007, 01:06 PM
Yet another reason to detest Wal-Mart.

My niece worked in one of their administrative places and after taking too long for lunch one day she was fired for "THEFT OF COMPANY TIME". I mean, really......THEFT?!

They also fired several workers in the town where I used to live because they had been caught on video tape eating expired candy which it was their job to throw out. They just ate a few crummy pieces of candy and were fired as THIEVES, when they were just ordinary hardworking people trying to make ends meet nibbling on what WalMart was throwing out. One woman was emotionally devastated; to be branded as a thief in her community was humiliation more than she could bear.

11-06-2007, 02:28 PM
Thats horrible...Ohh well just don't shop there. I try to advoid ours as much as possible. This time of year everytime I go in there i come out with a cold 3 days later.

11-06-2007, 07:12 PM
Her answer.."We're not the government.... we're Wal-Mart."

And people wonder why I don't shop there. Do you know how many of those cards they throw away each day because they can't be activated? I've worked in retail where we've had those sorts of gift cards and about a third of them don't work. All we do is make a notation that X-cards were unactivatable each day and toss them. We NEVER had to pay anything to the companies they came from until they were activated. So that's just bogus that they have to send them back to the companies!

11-07-2007, 02:27 PM
About gift cards...I refuse to buy those that are out on the floor. Last Christmas there was an ariticle circulating about people writing down the numbers off the card and and then a few days/weeks later, calling to see if it had a balance on it. If it did, they'd go online and use it. (Only the online retailers worked...but still!)

Also, our group of friends has a thing with buying gift cards that you can put your own amount on and putting the smallest amount possible and giving it as a gift and writing a huge amount on it. They gave a friend a dozen or so cards from Best Buy with a nickel on each one and wrote $500 on each. Then the giftee could act all disappointed when he redeemed it. He knew it wasn't $500, but really had no clue how much was on there. Apparently, they don't allow amounts under $5.00 there anymore!