Knit in the round from the center of the top down to the brim.
Start out by swatching your yarn and measuring your head. I used bulky yarn and size 10 needles. I stretched the swatch to mimic a snug fit around my head (if you want a looser fit, don’t stretch) which gave me about 6 stitches over 4 inches or 1.5 stitches per inch. The measurement of where I wanted the brim of my tam to be on my head was 22 inches.
Multiply the inches by the number of stitches per inch. In my example, it was 22×1.5=33. This is the number of stitches for the brim.
Double the number of stitches for the brim to get the stitch count for the largest part of the hat. 33×2=66 for mine.
Divide that number by 16 to get your cast on stitch count. 66÷16=4.125. I rounded down to 4 here and planned to make up any difference in stitch count at the decrease for the brim if I felt the need.
If you’re using lighter weight yarn and your cast on stitch count is more than 8, you can divide that number by 2 and add another increase round at round 32.
Cast on, spreading the stitches over 4 double points or on two or one circular needles, however you like to knit in the round.
1. Knit around.
2. Increase (also on rounds 4, 8, and 16): K1, yarn over (yo) to end of round. If you don’t want eyelet circles in the top of your tam, you can use any increase stitch you like instead of a yo.
Knit around on all other rounds.
By round 16 (or 32, if using lighter yarn) you should have reached your highest stitch count number. I was a little short at 64 stitches because of rounding down at cast on.
Knit until your hat measures 4 inches (more or less, depending on your taste) from the last increase round.
Knit 2 together to end of round. If I had followed this, I would have ended up with 32 stitches, so I skipped the last decrease and knit both of the last two stitches separately to get 33.
Knit another inch or so and bind off. This will create a rolled edge. If you’d like to do a knit 1, purl 1 ribbing, you could do that easily as long as your final stitch count is an even number.
You are welcome to distribute this pattern and use the ideas included and gift or sell whatever you make from it. But if you distribute it, please do so as a whole, with attribution and this info included. Thanks!