How to read a yarn label for gauge, needle size, and more

The top of the label is straightforward enough; "Rikka" is the name of the yarn. ("Noro" is the name of the manufacturer, and "Noro Rikka" is the yarn's full name. Sort of like the make and model of a car. "Toyota Camry")

Beneath the name of the yarn is the fiber content. Rikka contains 57% wool, 22% alpaca, and 21% silk. Like the ingredients in a nutrition label, you'll see the highest fiber contents listed first.

The next section of the label is small but mighty: packed with information you need.

• Gauge: How many stitches per 4"/10 cm
• How many rows per 4"/10 cm
• How many yards (meters) per ball
• What size needle to use in order to get gauge
• The standardized yarn thickness or weight (in this case, 5 Bulky)

In very small text, the first line reads "10 cm" / 12-14 / 18-20. 

The line beneath it suggests a needle size of US 8-10 (5-6 mm.)

What does this mean?

Well, 10 cm = 4 inches.

Once you've made a swatch (in other words, a small square sample of your full-sized knitting project) you're going to measure it.

Use size 8, 9, or 10 needles.

How do I decide what size needles to use?

• If you tend to knit tightly, use the largest size needle recommended or even one larger (size 11)
• If you tend to knit loosely, use the smallest size needle recommended or even one smaller (size 7)
• If you're not sure, split the difference! Or, choose one of the recommended sizes and gather data about yourself. :)

How to start your gauge swatch

To be safe, I'd cast on at least 20 stitches and work 20-24 rows in the stitch that comprises the bulk of your pattern. 

Then -- and I really suggest you do this, even though almost no one does this -- block the swatch and lay it flat to dry. 

How to measure your swatch

Place your ruler or tape measure parallel to a row of knitting. Count all the stitches (even half stitches) that fit within a 4-inch segment. 

According to the Noro Rikka label, you should have 12-14 stitches. 

Rotate your ruler or tape measure so that it's parallel to a column of knitting. Count all the stitches (even half stitches) that fit within a 4-inch segment.

According to the label, you should have 18-20 rows.

The yarn label isn't always "right"

A gentle reminder: you can match your gauge to exactly what the label says, and not be satisfied with the fabric you've knit. 

Do a common sense check. Perhaps you want a fabric with more drape and more "air" between the stitches. Or, perhaps you want a more structured fabric, as in a boxy jacket. 

As irritating as it is for impatient types like myself, it's best to knit multiple swatches if needed until you get exactly the fabric you want. Much better to redo a 20-stitch swatch than a 200-stitch sweater.