Knitting Math - 4 Vertical Patterns/Repeats

We all know by now that we need to keep an eye on our stitch gauge.  The number of stitches per inch is how we know whether a piece will be the size we were aiming for: too few and it's too big, and too many and it's too small.  But what about row gauge?

This is not the time to get faint of heart.  Row gauge is important for many types of patterns, and nearly always for vertical patterns.  Colorwork only works in exact numbers of rows (not "knit 4 inches"), and if your row gauge is off, your piece will be too long or too short.  Shapes that were intended to be circles become ovals, squares become rectangles, and the pattern becomes a funhouse mirror version of the original.  Knowing your row gauge makes several things easier.

The socks at left were knit and posted on Ravelry by Stacey14, from a pattern by Priscilla Gibson-Roberts in her book, Ethnic Socks and Stockings.  There are several patterns here, some running vertically and some horizontally.  If you need to shorten or lengthen a vertical repeat, what do you do?  Maybe you want a shorter version of this sock.  Now what?

Well, you need to do your math.  (This is why the Lord created calculators and scrap paper!)  If the total pattern repeat is designed to be 1 3/4 inches tall, and you want a shorter sock, no problem.  First, knit a swatch including two pattern repeats.  Measure your row gauge.  Does it match the pattern?  If yes, cool.  You'll want to decrease in whole repeats to maintain the look, so you'll decrease the finished size by increments of 1 3/4 inches.  If the total sock has a 12 inch leg, with each full pattern repeat you take out, you subtract 1 3/4 inches. Originally there were 6 repeats + cuff = 7 units of height.  Don't take off the cuff - it anchors the look.  Remove one or more of the leg motif repeats.

Total length in inches - (number of repeats x 1.75 inches) = new total length. 

But what if your row gauge doesn't match the pattern?  Well, there are two ways to go - try to get the row gauge, or live with your unique gauge.  I tend to go with the one that matches the pattern, because it retains the original shapes in the design.  If your stitches are right on, and rows are off, you have the right needle size, but not the right material.  Too few rows mean you need stickier needles (bamboo like Clover, or non-slippery plastic, like Denise) and too many rows mean you need slippery needles (Addi's or Boye.)  If this works, you're all set to move on. 

If you're already using the recommended needle material, it's probably you.  Maybe you knit a little tightly, or a little loosely by nature.  No worries.  Stick with your unique gauge.  Then to get the dimensions in the pattern, you may need to knit more or fewer total rows.  If you're knitting at 1 1/2 inches per pattern repeat, you'll need to do 7 repeats + cuff = 8 total to make it the length specified in the pattern. The design will look like a shorter, fatter version of the original, and if you like it, go with it. (If not, pick a new pattern!)

(Total length) 12 / 1.5 (height of repeat) = 8

Wouldn't it be cool if it all worked out that way?  Well, it usually does.  But sometimes you want your garment to be longer or shorter in an increment different from the repeat.  If you have a 2 3/4 inch repeat and you only need 4 more inches, you won't be able to work in full pattern repeats and still get the measurements you want.  That means you either pick a different pattern, or you live with a partial repeat somewhere.  Put the partial repeat in the less visible part of the garment, usually the bottom.  You'll do your regular math of

Row gauge x total desired length = total number of rows - then -

Total # of rows / number of rows in one repeat = number of repeats, with the remainder being the number of extra rows

If you need to do a partial repeat at the bottom, you'll want to work the top part of the pattern in the extra rows.  If you need to do a partial repeat at the top, do the bottom part of the pattern. 

You can do this.  Get some coffee or tea, and your scrap paper and calculator, and do the math first.  Sketch it on some graph paper to make sure it makes sense.  Write out your new directions as thoroughly as possible so you don't have to do the work again.  Then, get knitting!

Knitting Math 2 - short pattern repeats

Pattern repeats add a variable to knitting math.  The basic factors in knitting math are the stitch count per inch, and the row count per inch.  But what about the pattern repeat?  In this example, we'll work in the round, so the repeat has to line up exactly.

These mittens are my everyday winter mittens.  They have a "pattern repeat" of 4 stitches (2/3 of an inch, or .6666).  The stitches per inch is 6.  What does that matter?  Well, you'll need both numbers if you need to adjust the pattern to fit some other size.  Pattern repeat = 4 stitches in 2/3 of an inch.  Stitch count  = 6 stitches per inch.

My hand and the gauge and the original pattern all work out to the same size (I wear a mitten that's 8.25 inches around) so it works out nicely.  But my husband's hand is larger than the original pattern, so for him I'll have to modify to make it fit.  If I only mind the stitches per inch (6), my mitten will have a weird jog in it where the pattern doesn't line up, because the pattern repeats in 4s , not 6s. The mittens are stranded, which keeps them from being very stretchy, so I can't rely on stretch to save me if they're a little small.  What to do?

Well, the pattern repeat of 4 stitches = 2/3 of an inch.  If I measure my husband's hand, I discover that he needs a mitten that's 9.4 inches around.  If I take a look at the original pattern, I see that the pattern repeats 12 times in 8.25 inches (or six times on the front and six on the back).  Now I need to subtract 8.25 inches (pattern size) from 9.4 inches (the size I need for my husband).  I get 1.15 inches that need to be added to make a mitten to fit the hubby.  Size I have - size I need = amount of room I need to add (or subtract).

If I divide that 1.15 extra that I need by the pattern repeat of .6666 inches, I get 1.75, or one and three quarters of a repeat.  That means I need 7 more stitches around to make the mitten exactly my husband's size.  One more stitch (8 stitches) gives me a perfect pattern repeat of 2 (4 stitches in the repeat twice), or only one extra stitch over the entire circumference of the mitten.  I can work with that!  So, to make the mittens for my husband, I would need to add 8 stitches to the pattern, and just work those repeats in with the original pattern.  I can work the decreases at the top by starting them at the tip of the hubby's little finger, and follow the decreases a few extra times until I run out of stitches.
Amount of change in inches / length of pattern repeat in inches = number of pattern repeats needed.
Number of pattern repeats needed x pattern repeat in stitches = number of stitches to add.

The thumb is a pattern repeat of 2 (which is 1/3 of an inch), so that math is really easy.  I measure the original, subtract that measurement from the hubby's thumb measurement, and discover I need 3/4 of an inch extra.  That's 4 and 1/2 stitches.  I can afford to be a stitch short or a stitch over, so I choose over.  (Tight thumbs stink!)  I round the 4.5 stitches I need up to the next even number (6) to accommodate the pattern repeat, and I'm done.

Short pattern repeats give you more flexibility to modify size than long ones, but we'll work with long ones in the next article.  Knitting math isn't hard if you know the formulas and you have a calculator.  You can do it!