In my last post, we learned how to count stitches and rows in knitted fabric. Today, we’re learning how to measure knitted fabric. You know, with a ruler or tape measure.
Of course not!
- Use a good tape measure or a ruler. Tape measures aren’t always accurate: fabric ones have been known to stretch over time, and I’ve seen a couple of inexpensive plastic ones that were misprinted. The centimeter markings were accurate, but something had gone horribly wrong with the inches.
- Spread the stitches out on the needle to about the width of the finished fabric. If you’re working a circular needle, move the stitches down onto the cord.
- Measure the piece lying flat, rather than hanging.
- Actually flat, on a table or the floor; not over your leg or the arm of your chair.
- Measure from the bottom of the lower edge of the piece, to about the middle of the needle—that accounts for the length of the row on the needles once it’s worked.
Subtle but important: if your pattern and tape measure have both metric and imperial measurements, make sure you’re consistent about which measurement system you’re using. Things can get muddled if you’re referring to two different sets of measurements.
Your tape measure says that the piece is 11 inches long. That’s what the pattern calls for. You’re done, right?
Oh, absolutely not.
Swatch and Block the Swatch
Remember that little thing that we’re always talking about? The G-word? Remember that we’re always begging you to swatch, and to wash your swatch before you measure your gauge?
Crucial side note: all knitting needs to be “blocked” before you declare it done. For the vast majority of your projects, “block” should be read as “wash.” Specifically, wash the way you intend to wash the finished item. Unless you’re making garments to be worn in a runway fashion show in Paris, there’s no need to stretch and pin the pieces for blocking. The only type of knitting I do the stretch-and-pin treatment for is lace.
Here’s the thing: fabrics can change with washing. Row gauge can shift, your work might stretch out a little vertically. A length measurement of 11 inches before washing can easily become 12 inches. In the grand scheme of things, it’s less than a 10 percent change in the length, but an inch can be important.
If you’re making a small item—a hat, a sock, a mitten, for example—then there’s not so much length that a 10 percent difference is a huge deal. A sock leg that is supposed to be 6 inches long might come out to be 6½, nothing to stress about. And if it’s an item that doesn’t actually need to fit—a tea cozy, a scarf, a toy—then there’s no worry. As long as you’re consistent in how you measure—for example, measure both socks in their prewashed state—then you’ll be fine.
But if it’s an item that has specifically placed shaping—the waist of a sweater, for example—or is to fit a specific size, or is to be sewn together with another piece, then you better make sure that you get these lengths right.
Which is to say when the pattern says “work sleeve until it measures 18 inches from cast-on edge,” then that 18 inches is supposed to be the blocked length.
I’ll let you have a lie-down. Come back when you’re ready.
The upshot: when you swatch for a garment, you need to actually measure your gauge pre- and post-blocking.
If your row gauge doesn’t change after blocking, then you can breathe a sigh of relief (and perhaps consider buying a lottery ticket). This means that when you’re working the sleeve, you can safely measure the gauge of the fabric on your needles and be done with it.
But if your row gauge does change, then you need to take that into account. Specifically: if the fabric stretches vertically with the washing, then you need the sleeve to measure 18 inches after it’s been washed. Which is to say that if you know that your fabric grows with washing, then the prewashed pieces will need to be shorter than the finished length you’re aiming for.
Two Approaches to Row Gauge
There are two ways to approach this.
You can do it by counting rows. Many designers give row counts for pieces like this, precisely for this reason. And if even the row count isn’t there, you can work it out. If the sleeve is to be 18 inches long, and the blocked gauge is 7 rows per inch, you know that you should work 7 x 18 = 126 rows.
Or you can do it by ratios.
For example, if your pre-blocked gauge is 30 rows per 4 inches, or 7.5 rows an inch, and your blocked gauge is 28 rows per 4 inches, or 7 rows per inch, calculate the percentage change by dividing the blocked gauge by the unblocked. So: 7/7.5 = .9333
Take the length you’re aiming for, and multiply it by that number. In this case, we’re aiming for 18 inches, so the calculation is 18 x .93333 = 16.8 inches. That’s the length you should measure on your needles so that after washing the piece turns out to be the right size.
It’s amazing how a tiny little half-a-row can add up to over an inch of difference in the finished item.
Put another way, if you work the full 18 inches of fabric and then wash it, you’ll end up with a sleeve well over 19 inches long.
This may seem like a lot of fuss, but it’s crucial for a few reasons: if you work too many rows, then the pieces will come out too long. But also consider: not only does your piece come out to be the wrong size, but you risk running out of yarn. And if you’re needing to sew pieces together, such as sleeves, then the different edges might not actually fit together.
The good news is that this is all much easier for us than it was for previous generations of knitters: they didn’t have a tiny computer in their knitting bags, did they? Your phone isn’t just for listening to podcasts while knitting—it’s also for helping you make sure that your finished project comes out the right size!