Someone Please Check My Math Before My Brain Explodes

I’m using this pattern to make a purse for a friend but the pattern pieces seemed a little small so I printed them at 120%. I also have to increase the dimensions referenced in the pattern by 120% and I think I’ve done the figurin’ correctly but can you confirm that I’m not using some little-known form of Appalachian *stomps foot* naught-from-naught-is-naught Math? Theeenks!

  • 3″ x 8.5″ → 4.2″ x 11.9″
  • 3″ x 10.5″ → 4.2″ x 14.7″
  • 3″ x 20″  → 4.2″ x 28″
  • 4.5″ x 4.5″ → 6.3″ x 6.3″
  • 6″ x 16″  → 8.4″ x 22.4″

Revised Math by authority of Amy’s Mom:

  • 3″ x 8.5″ →3.6″ x 10.2″
  • 3″ x 10.5″ → 3.6″ x 12.6″
  • 3″ x 20″ → 3.6″ x 24″
  • 4.5″ x 4.5″ → 5.4″ x 5.4″
  • 6″ x 16″ → 7.2″ x 19.2″

Look right? Thank you, dear reader, for elucidating mah ciphers!

9 Responses to “Someone Please Check My Math Before My Brain Explodes”

  1. lydia Says:

    Okay, I am not a seamstress, so perhaps there is some sewer’s math I’m not aware of, in which case my response to this email is totally obsolete and will make me look dumb. Luckily I don’t care if I make a fool of myself and am a geek who likes to do math problems. So in comes my $.02.

    120% of 3.0 = 3.6

    If, however, you want to INCREASE the size of the pattern by 120%, that would be 6.6.

    So, for example, if you put something on the copy machine that is 10″ x 10″ and print it at 120%, it is going to come out at 12″ x 12″. Right? Or am I totally wrong here?

    If that’s right, and if that’s what you did and you now want to cut the fabric correctly, what you do is multiply each measurement by 1.2.

    But we really need a second opinion on this because I would hate to be the stranger who made you cut your fabric incorrectly, thus resulting in your model going down the Project Runway with her derriere showing. Or in your friend not being able to fit her wallet in that ADORABLE BAG.

  2. Mymsie Says:

    @Lydia: Damn, I messed up originally but I get what you’re saying. The equation would be:

    Starting with 3″
    x/3 = 120/100
    cross multiply and divide and x = 3.6 but is that the answer or do I add that to 3? Hmmm…

    Someone please help us!

  3. Amy Says:

    Uh, I’ll ask mom!

  4. Amy Says:

    Is there a reason you can’t just stick the pattern pieces on the fabric and cut it out and who cares how big the original piece size was? It sounds like you are trying to precut the pieces that will then be used to put pattern pieces on.

    Anyway, I would think multiplying all dimensions by 1.2″ is the right way to go. (Your later example is essentially the same as multiplying by 1.2… don’t then add to it as well. So 3 becomes 3.6, 8.5 becomes 10.2, etc.)

    I asked mom anyway in email.

  5. mymsie Says:

    @ Amy: I’ve enlarged the actual pattern pieces but there are other pieces, for example, straps, pockets, the bag gusset, that are just rectangles of a certain dimension.

  6. Amy's Mom Says:

    If I understand correctly what you are doing… you have enlarged the printed pattern pieces by 120% but other pattern pieces are simply listed as “Cut one @ 3″ x 8.5″ and you need to know how to enlarge these by 120%. I’ve tried a couple of ways and they both came out the same so hopefully this is correct. Using my proportional scale (available at art and office supply stores) 3″ enlarged 120% = 3 5/8″ and 8.5″ = 10.25″ Figuring by calculator… 3 x 120% = 3.6 and 8.5 x 120% = 10.2.

    I am no geek and I hate math except when I’m figuring for quilting, yardage, knitting and the like. But as a double check why not draw a 3″ x 8.5″ rectangle and enlarge it 120% like you did the other pieces and if it indeed enlarges to 3 5/8” x 10.25″… Bingo!

    I’m heading out in 5 minutes to go to a 3 day knitting convention! I imagine I’ll be doing some fun math there….. hmmm how many skeins of yarn will I need to make that sweater……

  7. Amy Says:

    Stupid English vs metric! Funny how it can be right at 10.2 but then would require another conversion to get it in inches. David has a handy conversion calculator for his woodworking so I imagine that would be handy in a sewing version too.

    That’s funny that my mom commented. She rarely comments at my blog!

  8. i don't have a name Says:

    you guys are nuts.
    i feel kinda krrraaazzzyyyy
    suck it!!

  9. jose Says:

    16/4*4+9-8 does this =2 ??

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