Knit Hat Calculator
Pick a size (or enter a custom head measurement) and your gauge to get a top-down crown increase plan, body height, and brim guidance.
Top-down vs bottom-up construction
This tool assumes the common top-down knit beanie method: cast on a small number of stitches at the crown center (worked in the round on double-pointed needles or magic loop), increase evenly at 8 points every round until the circumference matches your head measurement, then work straight down to the brim. That's the opposite order from crochet hats, which are almost always worked bottom-up with the crown decreases saved for last. Top-down has one practical advantage: you can try the hat on as you knit and stop exactly when it's long enough, rather than committing to a total height up front.
Why negative ease is larger here than for crochet
Knit fabric — especially stockinette — has substantially more stretch than most crochet fabric, so a knit hat can use more negative ease and still go on comfortably while fitting snugly once worn. 1.5 to 2 inches is typical for a plain stockinette beanie; a ribbed hat (which stretches even more) can sometimes use up to 3 inches of negative ease and still feel right.
The ribbed brim
Most top-down beanies switch to a smaller needle and a stretchy rib pattern (k2, p2 or k1, p1) for the last 1.5 to 2 inches, which helps the hat grip snugly at the hairline without needing extra negative ease built into the main body. Bind off in pattern using a stretchy bind-off (like a sewn or German twisted bind-off) rather than a standard one — a too-tight standard bind-off is a common reason a well-fitting hat won't stretch over the head at all.