It happens to everyone: that special skein of yarn just begs to be made into a hat, but the patterns you like are written for a different weight. Fortunately, hats patterns are notoriously easy to adapt, especially if they include charts. Take these few steps, and you can use the pattern with confidence!

You know what I am going to say before I start to say it, but here goes anyways. Start the process by making a swatch. You need to determine your stitch gauge, unless of course you enjoy making hats the size of oranges or watermelons. Are you listening? In most cases, your hat will not use up all the yarn in the skein, so you can make the swatch and then wash and dry it to make sure that the size doesn’t change. Conversely, if you are worried about running out of yarn, you can make the swatch, measure it, and then rip it out prior to starting the hat.

When you have determined your gauge, make another swatch. Sorry about this, but you need to take the time to see how the pattern stitch is going to look in your yarn. You may find that what looks striking in fingering looks fussy in bulky. You might discover that the colors are too busy for the stitch. You might discover that the pattern stitch changes your gauge! It is worth taking the time to make sure that this pattern works with your yarn.

Now you are ready to do basic math. Multiply your gauge by the number of inches needed to make a fabric that encircles your head. Once you have that number, compare it to the number of stitches used for the cast-on. Read through the pattern to see if the numbers change after the brim is complete. This will give you an idea of how many stitches you need to add or subtract.

You have another step to take before you cast on, however, because you need enough stitches to finish pattern repeats. This may or may not align perfectly with the number you came up with based on your gauge swatch. Decide if you want the hat to be a bit bigger or smaller. Personally, I have large curls and voluminous tresses badly prone to hat hair, and so I’d rather have a hat that’s a bit on the large side. If you keep your head shaved, you may want the hat tighter.

At this point, look at the chart that shows the stitch repeats. Many hat patterns give charts that cover one full repeat, asking you to then use it a specified number of times. Can you add or subtract repeats to bring the pattern in line with what your yarn requires?

As an example, suppose I want to make a hat out of fingering weight yarn that I knit up at seven stitches to the inch. I have a dynamite pattern for bulky weight that asks me to cast on forty-eight stitches. Since I want a hat with a twenty-inch circumference, I need to adjust the pattern so that I will have around one hundred and forty stitches – that’s over three times what the pattern asks for! Fortunately, I have a chart that shows a repeat of twelve stitches for both the rise and crown. One forty divided by twelve doesn’t come out evenly, so I need to decide if I want to knit twelve repeats of the pattern for a total of one hundred and forty-four stitches, or eleven repeats for a total of one hundred and thirty-two. Given my hair, I’m opting for the former. From here, I can use the pattern as charted, but with twelve repeats instead of the original four.

Keep in mind that different gauges use different amounts of yarn. Fortunately, hats don’t use that much; an Internet search will give you a rough idea of how much yarn you need at this weight. If the pattern calls for lace, you’ll need less yarn; if the pattern calls for cables, you will need more. A few hats in a particular gauge will give you a feel for how much yarn you need.