Worsted weight yarn (color of your choice)
Crochet hook (size appropriate for the yarn)
Start by making a slip knot and chaining an appropriate number of stitches to achieve the desired circumference of the hat. For an adult-sized hat, you can start with around 80-90 chains, but you can adjust it according to your preference.
Join the last chain to the first chain with a slip stitch, being careful not to twist the chain. This creates a ring.
Chain one to start the first round and work single crochet stitches into each chain around the ring. Join with a slip stitch to the first single crochet.
Chain three to start the second round. This counts as the first double crochet stitch. Work one double crochet into the next stitch and continue this pattern (1 double crochet in the next stitch) all the way around. Join with a slip stitch to the top of the chain three.
Chain three to start the third round. Work one double crochet into the next stitch, then work two double crochets into the following stitch. Repeat this pattern (1 double crochet, 2 double crochets) around, joining with a slip stitch to the top of the chain three.
Continue increasing the number of double crochets in each round by adding one more double crochet between increases. For example, in the fourth round, work (1 double crochet, 1 double crochet, 2 double crochets) in each pattern repeat. Join with a slip stitch to the top of the chain three.
Keep increasing and working even rounds of double crochets until the hat reaches your desired height. Typically, 6-7 inches (15-18 cm) is a good length for an adult-sized hat.
Once you’ve reached the desired height, it’s time to create the bobbles. To make a bobble stitch, work the following steps into the same stitch: yarn over, insert the hook into the stitch, yarn over, and pull up a loop (you’ll have three loops on your hook). Yarn over and pull through two loops, leaving two loops on the hook. Repeat this step four more times, always in the same stitch. In the end, you’ll have six loops on the hook. Yarn over and pull through all six loops to complete the bobble stitch.
Work one single crochet stitch in the next stitch to secure the bobble and keep the hat’s shape. Repeat steps 8 and 9 all the way around the hat, creating bobbles at regular intervals. Join with a slip stitch to the first single crochet.
To finish off the hat, cut the yarn, leaving a long tail. Thread the tail through the yarn needle, insert it under the loops of the last round, and weave it in to secure the stitches. Trim any excess yarn.