Avoid having your finished pieces not fit right by making a gauge swatch first. By knowing how many stitches and rows per inch your fabric will be, you can accurately estimate how to construct your finished pieces.

Using the same stitch you’ll use in your project, make a chain of stitches that’s between 8″ (20cm) and 12″ (20.5cm) long.

Use the same joining method you’ll use in your project to join the chain together to start your next row.

Keep going until it’s at least five rows tall. The taller you make it, the more accurate your rows-per-inch measurement will be.

Measure the number of stitches in a set amount of inches. Here, we have 13.5 stitches per 4″, or 3.375 stitches per 1″.

Measure the number of rows in a set amount of inches. Here, we have 2 rows per 7/8″, or 2.25 rows per 1″.
Once you know your stitches and rows per inch, this can tell you a lot about how to construct your finished pieces. For example, to make a hat that’s 22″ (56cm) around and 7″ (18cm) tall out of the red yarn in the pictures, you would make a foundation chain of 74 stitches, then nalbind for 16 rows.
You can round up or down to get whole numbers for your stitches. Rounding up will give you a looser fit, and rounding down will give you a tighter fit.