## Thursday, September 18, 2008

### Knitting Math Part 2

* * * * * * * W A R N I N G * * * * * * *

The last time we talked about knitting math, I covered how to calculate proper yardage for a project. That information can be used to design a new pattern or change a current pattern into a different gauge.

The next step involves plotting the gauge to full scale. Converting an existing pattern will give you exact cast-on, decreases and bind-off stitches to match your new gauge.

The simplest part of this takes some measuring or pattern checking. For instance, if you have a sweater where the front is 20 inch wide by 22 inches long. Your gauge measures at 4 stitches to the inch and 3 rows to the inch, then the math would look like this:

20 x 4 = 80 stitches to cast-on

22 x 3 = 66 rows will result in proper height.

Most of the time when a pattern tells you to knit until piece measures so many inches, I don't convert that section. You'll just knit to that length whether it's for armholes or necklines.

The trickier part of pattern conversions comes when you have decreases over a defined area. For example on sleeve cap shaping. If the pattern reads decrease at edge 1 stitch every other row. This will have to be examined to your new gauge and as I had to do this just recently I will give you the sample I worked on...

Original pattern calls for this cap sleeve shaping:
BO 5 st at the begin of next 2 rows (50 st remain)
DEC 1 st at each end of every needle every other row 4 times,
Then every row 14 times
BO 14 remaining st

The Shaping of Cap on Sleeves:
Pattern schematic has the width at 17 inch at the point where the shaping begins. Shaping of cap will happen over 7.5 inches ending with a width of 4 inches to bind-off. From the above description of the original shaping we see that the first BO action is dramatic. This quick BO will create a notch on both sides which should match the bind-off for the armholes.

We then have more decreases, but at a slower pace. A total of 8 stitches decreased every other row. You'll need to look for the row gauge of the original, which is 13 rows = 3 inch (or 3.25 rows per inch). Decreasing happens over 8 rows (every other row [2] x 4 dec)... then we calculate over the row gauge (8 rows ÷ 3.25 per inch = 2.46 in). This tells us that the slower pace decrease happen over a 2.46 inch span.

We'll then match this with our row gauge... 13 rows = 3.75 in (or 3.5 rows per inch) – please note I round up when I need to. We take this number (3.5) and find how many rows we'll need to do the slower decreases.

3.5 rows per inch x 2.46 inch = 8.61 rows

This shows not much of a change or difference between the original row gauge and new row gauge. Yet my stitch count is greater and I have to decrease significantly over a shorter distance.

The remaining 5 inches would have to accommodate a larger decrease amount compared to the original gauge. Instead I take a look at an overall decrease of the full sleeve. If I calculate so see how many times per row I would need to decrease my stitch count from 70 stitches to 20 over the full cap... 50 stitches ÷ 2 (for each edge of cap) = 25. Then divide that times our row gauge: 25 ÷ 3.5 = 7.14 inches. That puts us closer to the length of cap shaping we need verses planning out each row of decrease.

To make up for the .35 remaining I'll do a non-decrease row in the beginning which will give us plenty of length on the cap.

My pattern conversion:
BO 6 st at the begin of next 2 rows (70 st remain)
K 2 row in pattern. Ending on WS row.
DEC 1 st at each end of every needle until 20 stitches remain
BO 20 remaining st

Pattern converting can become a challenge. If you break it down section by section and have your calculator, pencil and paper handy it can work out just fine. Always take notes and jot numbers down. It's a process and if you need a break, take one.

Just knowing that it is possible to end up with a garment worth knitting is huge to me. I'm sure most people would say it's just not worth it. That is totally fine too. I would rather know that it's possible then to feel like there is nothing I can do about it.