This is my go to pattern when i need to make an adult beanie quickly. It fits most adult head sizes 21"-24" and it can easily be adjusted or customised.
Stitches will be in US terms otherwise general crochet knowledge is assumed.
Magic loop - Crochet cast-on
ch - Chain
dc - Double crochet
FPdc - Front post double crochet
BPdc - Back post double crochet
Step 1: Gather Supplies
For this pattern you'll need:
-a 4.5mm hook
-Fingering (4ply) weight yarn
-Yarn needle (tapestry needle)
Step 2: Getting Started and Increase Rounds
Pattern Note - at the end of every round slip stitch back into the first stitch to complete.
Start with 10 dc into a magic loop, pull loop tight. (If you don't understand magic loop just start with a ch3 joined to work in the round instead)
2nd to 8th round - dc in each, evenly increasing by 10 dc in each round (I stagger my increases for a rounder base, but it's not required knowledge to make the hat)
You should have 80 dc in your last round.
Step 3: Body and Ribbing
9th to 14th rounds - dc in each stitch
15th to 19th rounds - ch1, *FPdc, BPdc* rpt till end
Step 4: Finishing
And that's pretty much it finish off and weave in your ends and your new hat is ready to wear.
I usually give my finished pieces a soak in some wool wash before i'm done. I recommend it, but it's not a requirement.
You can also see in the pics i've attached that i've made a couple variations to show what you could do. The blue and red one was just a simple colour variation on the basic pattern but the green and grey hat is from my personal collection and was made to hold my messy dreads. I started with 12 increase rounds instead of 8 (120 stitches around) I made the body a bit deeper... I think it was about 12 rounds instead of 6, then had to add a few decrease rounds so i could get back to 80 stitches before the ribbing.