Numerical Knitting

January 22, 2008

It’s all about the math, dude!

Filed under: Knitting — by bethc @ 12:08 pm

I spend a rather relaxing week-end knitting on a Tomten (Ravelry link)for Bunny. I’m liking the Peace Fleece more and more. From my swatch I did some math to figure out how many stitches to cast on. I measured a sweatshirt Bunny has to get a size, 33″ around the hem. My post washing gauge was 30 stitches in 6.5 inches (about 4.6 stitches per inch) multiplying by 33 and then rounding up (always round up when knitting for a growing child) to get a multiple of 8 I ended up with 160 for my magic cast on number.

I cast on the 160 and was knitting merrily along. I measured my swatch again, as well as the sweatshirt and decided that 45 ridges would give me the correct length. Last night I looked at what was left of my first ball of yarn, and what I had knit, and hit the panic mode! Clearly I was not going to have enough yarn…

I considered turning it into a problem for my students (and I still may) but I went to work figuring out how much yarn I would need. In case you, like me, like this sort of thing here’s my thinking.

I have knit 160 stitches x 15 ridges and used about 3/4 of a skein

That means 4,800 stitches (160 x 15 x 2) is 3/4 of a skein, so 1,600 stitches in 1/4 of a skein, or 6,400 stitches per skein.

So, how many stitches in my tomten?

Body before the break for sleeves: 160 x 45 x 2 (stitches, ridges, rows per ridge) = 14,400

Body above the break for sleeves (using the fact that the pattern calls for 40 ridges before the sleeve and 28 after and I am using 45 before I figured I should do 32 after): 80 x 32 x 2 = 5,120

Sleeves (again I used proportions from the pattrn and my numbers to get): 2 x 65 x 63 x 2 = 16,380

Hood (more proportions): 100 x 32 x 2 = 6400

Adding them all up: 14,400 + 5,120 + 16380 + 6400 = 42,300

42,300 stitches/6,400 stitches per skein = 6.6 skeins

I have 4 skeins, so I figure I better order at least 3 more and I’m thinking 4 just to be safe… I can always make more mittens!


  1. Coolest. Math problem. Ever!!
    I bow down to your wonderful teacherli-ness (huh? you know what I mean, right?!)!!

    Comment by mamasutra — January 22, 2008 @ 1:26 pm |Reply

  2. Thank you, thank you, thank you for posting this. I really want to make a Tomten jacket for my 8 year-old nephew and have 4 skeins of Peace Fleece and was hoping that it would be enough. Clearly it is not, so off I go to order some more!

    Oh and you rock at math!

    Comment by KT120 — April 27, 2009 @ 4:52 pm |Reply

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