Here's the formula for the "basic beanie" or "basic bucket" hat that will fit every time!
I usually use a soft worsted like Caron Simply Soft but you can use any yarn with an appropriate hook.
If you are not sure how to do double crochet stitches, check out the video tutorials.
Basic crocheted beanie - worsted weight, H hook
Each round begins with a chain 2 that counts as a dc, and ends with a slip stitch in the top of the chain for joining.
Round 1: 12 dc (US double crochet) in 3rd chain from hook, join with slip stitch
Round 2: 2dc in each dc around, 24 dc total
Round 3: * dc in next dc, 2dc (inc) in next dc * around, 36 dc total
Round 4: * dc in next 2 dc, 2dc (inc) in next dc * around, 48 dc total
Round 5: * dc in next 3 dc, 2dc (inc) in next dc * around, 60 dc total (stop increases for kid size)
Round 6: * dc in next 4 dc, 2dc (inc) in next dc * around, 72 dc total (stop increases for most adults)
Round 7: * dc in next 5 dc, 2dc (inc) in next dc * around, 84 dc total (stop increases for really big)
Work rounds evenly: 5 more rounds for kids, 6 for most adults, 7 for really big
Work three rounds of fpdc/bpdc ribbing: Work just like dc rounds, but instead of placing the hook in the top of the stitch below, work alternately around the post of the stitch.
Front post - insert hook from the front (right side), around the post, then to the front
Back post - insert hook from the back (wrong side), around the post, then to the back
Now that you have the basic formula down, you can adjust based on your preferences - more/less ribbing, longer/shorter sides, etc.
Here's a great rule of thumb on sizing… the diameter of the circle (straight across the widest part) at the end of your increase rounds should be a little less than 1/3 of the final circumference you are going for. So, if we are shooting for these sizes (in inches):
20 older kids
19 younger kids
The flat circle should have a diameter (in inches) of about:
6.25 older kids
5.75 younger kids
Regardless of how many increase rounds the pattern says, if you stop increasing at these measurements and start working “even” the hat ought to fit ok. This way, you can use any yarn and any hook and still get the sizing where you want it to be!
Here are a few examples of hats I've made using this same basic pattern, and adding a few embellishments. ;o)