How do you knit a gauge swatch? Most knitters (and at one point in my knitting life, I was guilty of this too), cast on 10 or 15 stitches, work in pattern (usually stockinette) until they have an inch or so of knitting, then get out a ruler or tape measure and count how many stitches they have in one inch. They leave the stitches on the needle while they are doing this and sometimes even count the selvage stitches.
This is wrong.
I know I always say, "There's no wrong way in knitting," and usually that's true. But when it comes to swatching, the method described above is 100% wrong. Don't waste your time. You'd do just as well to not swatch at all. Seriously.
Leaving the stitches on the needle instead of binding off distorts the gauge. It allows you to squish or stretch the knitting to match what you want it to be, and it will look right because the needle forces the stitches to stay put. Measuring over just one inch does you no good at all. It's very easy to ignore that fraction of a stitch over one inch, but over 4 inches, 1/4 of a stitch per inch (that you didn't notice over one inch) becomes a whole stitch, which is significant to the size of your finished garment. As for including selvage stitches in that measurement, just don't do it! Because they are at the selvage, they are shaped funny and not a good indicator of what size the majority of your stitches will be.
So, now let's talk about how you are supposed to knit a gauge swatch. When I swatch (and I'll openly admit I don't always do it!), I cast on at least 6 inches worth of stitches (or what I think will be 6 inches worth of stitches) and work in pattern to at least 4-6 inches long. If there is more than one stitch pattern in the garment, I will try all of them on my swatch. I'll knit one stitch pattern for a few inches, then switch to the next one. So, my swatch might end up longer than 6 inches, but it's always about 6 inches wide.
I know what you're thinking: Seriously, Amanda?! Why would you do that?! If the pattern says, "X stitches and x rows over 4 inches in stockinette stitch, why bother knitting the other stitch patterns?" I have a few reasons. First, it gives me a chance to see if I like knitting those stitch patterns. There are a lot of stitch patterns out there that look great but are a giant pain to actually knit. Better to discover that now rather than later. Another reason is to see if the stitch pattern and my yarn work well together. I enjoy knitting with hand painted yarns, and sometimes the pattern that I'm working so hard to create is lost in the riot of colors in the yarn. Again, better to discover that now. Finally, it gives me a chance to become familiar with all of the stitch patterns used in the garment and ask any questions or look up any unfamiliar techniques before actually starting the garment. That way, there are no surprises.
As you can see in the swatch below, I worked 2x2 ribbing, then stockinette, then 1x1 ribbing. I wasn't sure which ribbing I would prefer, so I tried both. I even picked up stitches along the edge and knit a bit of 1x1 ribbing, the same way the band of the cardigan will be worked. I prefer the way the 2x2 looks, but it pulls in too much. So, for the bottom band, I'll probably use 1x1. I'll decide for sure after it's blocked, but we have a few things to do before we get to that point.
Okay, so you've knit your 6" x 6" swatch. Now what? Lay it flat and measure it. Note it's dimensions as well as your stitch and row gauge. Write it down.
Lay your knitting flat (really flat; not on the arm of the couch or over your thigh; really flat, like on a table on the floor) and place a pin through a column of stitches. Make sure this is not in the selvedge. See how my pin below is several stitches in from the edge? That's what you want.
Gently, without squishing or stretching the fabric, measure 4 inches (or more, if you can) from that pin and place another pin.
Now measure the row gauge the same way.
Moving on: So you have your swatch, you've measured and noted its actual dimensions, and you've checked the gauge. And now you think you are done, don't you? Not so fast, grasshopper! It's time to give your swatch a bath. Treat the swatch the same way you will treat your finished garment. If you will machine wash and dry the garment, do the same to the swatch. If you will hand wash the garment, do the same to the swatch. I just soaked my swatch briefly in a little bowl of water. I didn't use any soap or detergent. This is superwash wool (Malabrigo Rios; colorway: Arco Iris), so I will machine wash and dry my swatch just to see how it behaves, but I don't actually plan on doing that to my final sweater, so I'm not doing it to my swatch for the sake of measurements.
Once your swatch is dry, measure it again. Note any shrinkage or stretching. This means re-measuring everything! My swatch grew a little bit. My new stitch gauge was 19 1/4 stitches/4" (which is 4 13/16 sts/inch), but my row gauge stayed the same. This is important because you'll need to account for this when knitting your garment. Are you happy with how the swatch looks and how it feels? Did the color bleed? What else can you learn from this?
Now your swatch is done!! Aren't you glad you went to all that trouble? Look at how much you learned! You know if you like knitting with that yarn or not. You know if you like the stitch pattern or not. You are a well-informed, educated knitter!
That swatch that you just spent so much time on? Well....I hate to say it, but in some ways, it's a liar. It's a good starting point, but there are so many things that affect your gauge. Your mood, the weight of the garment as it grows on your needles, even the type of needle you use. Wood, plastic, bamboo, metal....even if they are all the same size, changing the material of the needle can result in a different gauge.
Let me tell you a story: Once upon a time (October 2013), there was a girl (me) who had some gorgeous yarn and a plan. Her plan was well-thought-out. Pictures had been drawn, swatches (okay, just one) knit, and maths computed. So, she got out her needles and cast on for a sweater. She was instantly in love with the sweater. The stitch pattern was perfect and showed off the hand painted yarn to great advantage. The yarn was soft and lofty and beautiful. She would stop every few rows and just admire her work. One of the times she stopped to admire, she thought, "Wow, this looks big," but she ignored her thought and continued working. The next time she stopped to admire (just a few rows later), she thought, "Yep. This is definitely too big. I wonder what my gauge is." 4.5 stitches per inch. All of her numbers were based on her swatch, which measured 5 stitches per inch. After much mental wrestling with herself, she realized that she would not be happy with her final garment if she continued on her present course. A measly half stitch per inch doesn't sound like much, but it would have been the difference between a 44" sweater and a 49" sweater. That's significant. (Remember that 1/8 of a stitch we talked about before. Even that small of a number can affect the finished size of a garment.)
So, our heroine undid her work and started over. She took this crummy picture before she ripped everything out:
After reworking the numbers for 4.5 stitch/inch (though she could have just as easily dropped down a needle size), she started over. She wasn't sad because she loves the yarn and the stitch pattern, and she wasn't really *that* far along yet. It didn't take her long to catch up to where she was when she ripped out, and life is good. Now, several months later, the sweater is done and is one of her very favorite things ever. It will also be the star of it's own blog post soon.
It would seem that the moral of this story is that swatches lie. And while that's true--in this instance, the swatch did, in fact, lie--the real moral of the story is that as knitters, we have to be flexible. We have to remember that, no matter what, it's just sticks and string. Most yarns don't mind being ripped out and reknit, And if we loved knitting it the first time, we'll love it just as much the second time. AND, the swatch wasn't a total waste of time because look at how much you learned about the yarn and stitch pattern. You also know if the finished garment will grow or shrink. As for the gauge, chalk it up as a learning experience and move on!