In short

The Craft Yarn Council's head circumference chart runs from 9 to 12 inches for a preemie to 21 to 23 inches for a woman and 22 to 24 inches for a man. Make the hat about 2 inches smaller in stretchy acrylic and about 1 inch in cotton, so an adult woman's hat is roughly 19 to 21 inches around.

Crochet hat size chart — A crochet hat size chart matches a head circumference, measured with a tape around the forehead, to the finished circumference, crown diameter and height of a crocheted hat, usually with a little negative ease so the hat stretches to fit snugly.

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A crochet hat that fits is a matter of three numbers: the head’s circumference, the hat’s finished circumference and the number of stitches that gets you there. The first comes from a tape measure and the Craft Yarn Council’s chart, the second from a small allowance called negative ease, and the third from your own gauge. This guide gives the chart, then the method for turning it into a stitch count, with every formula written out. It does not give a hat pattern: for that, it links to designers who publish theirs free.

This guide uses US crochet terms, where single crochet (sc) is the UK double crochet (dc), and the Craft Yarn Council’s yarn categories: most hats are made in Medium (4) worsted yarn, often acrylic, with a 5.5 mm (I-9) hook, in half double crochet (hdc) or single crochet, while Bulky (5) yarn takes a 6 mm (J-10) to 6.5 mm (K-10½) hook and cotton gives a firmer fabric with less stretch. Hook letters vary by brand, so trust the millimeters.

At a glance: head circumference to hat size

Size (Craft Yarn Council)Head circumferenceIn cmFinished hat, 2 in lessFlat crown diameter
Preemie9 to 12 in23 to 30.57 to 10 in2.2 to 3.2 in
Baby14 to 16 in35.5 to 40.512 to 14 in3.8 to 4.5 in
Toddler16 to 18 in40.5 to 4614 to 16 in4.5 to 5.1 in
Child18 to 20 in45.5 to 5116 to 18 in5.1 to 5.7 in
Tween20 to 22 in51 to 5618 to 20 in5.7 to 6.4 in
Woman21 to 23 in53 to 58.519 to 21 in6.0 to 6.7 in
Man22 to 24 in56 to 6120 to 22 in6.4 to 7.0 in

The first three columns are the Craft Yarn Council’s Head Circumference Chart, from its 2018 Standards & Guidelines for Crochet and Knitting (page 19), which its website repeats. The last two columns are our calculation: the head circumference minus 2 inches (the negative ease Oombawka Design allows for acrylic yarn), then that finished circumference divided by pi (3.14). For cotton, subtract only about 1 inch.

What head circumference does each crochet hat size fit?

The Craft Yarn Council’s chart is the reference most pattern designers start from, and it gives a range for each size rather than a single number. Ranges are wide for the youngest (a preemie is 9 to 12 inches) and narrow for adults, where a woman is 21 to 23 inches and a man 22 to 24. The chart gives no ages, so a designer who writes patterns by age has to choose a circumference for each.

Oombawka Design Crochet’s hat chart, by Rhondda Mol and updated for 2026, does that, and adds the hat height. It is one designer’s chart, not a standard, and other designers’ differ by an inch or so: her own free beanie pattern lists a newborn at 13.5 inches where the chart says 14.

SizeHeadFinished hat (2 in less)Flat circle diameterHeight, mid earHeight, base of earHeight, slouch
Preemie12 in10 in3.18 in4 in4.5 in5 in
Newborn14 in12 in3.82 in4.5 in5 in5.5 in
0 to 3 months16 in14 in4.45 in5.25 in6 in6.25 in
3 to 6 months17 in15 in4.77 in5.5 in6.25 in6.75 in
6 to 12 months18 in16 in5.09 in5.75 in6.75 in7.25 in
1 to 3 years19 in17 in5.41 in6.25 in7 in7.5 in
3 to 5 years20 in18 in5.73 in6.5 in7.5 in8 in
6 to 10 years21 in19 in6.05 in7 in8 in9 in
Adult small (teen)22 in20 in6.36 in7.25 in8.25 in10 in
Adult medium23 in21 in6.68 in7.5 in8.75 in11 in
Adult large24 in22 in7 in7.75 in9 in12 in

The numbers are Oombawka Design’s, in inches; its page also gives centimeters. Its adult head circumferences, 22 to 24 inches, fall within or at the top of the Craft Yarn Council’s woman and man ranges (21 to 23 and 22 to 24 inches). When in doubt, measure the head.

How do you measure a head for a crochet hat?

Use a flexible tape. The Craft Yarn Council’s instruction is to place the tape across the forehead and around the full circumference of the head, keeping it snug for an accurate result; Oombawka Design says to measure the widest part of the head. Hair, a thick headband or a bun changes the number, so measure the way the hat will be worn. Write the measurement in inches and use it in the formulas below.

How much smaller than the head should a crochet hat be?

About 2 inches smaller for stretchy yarn, and about 1 inch for stiff yarn. Oombawka Design allows 2 inches of negative ease for medium (4) and DK (3) acrylic yarns and recommends about 1 inch for less stretchy ones such as cotton. The idea is that a hat sized exactly to the head would sit loose, because the fabric stretches and then does not spring back.

Oombawka Design ties the allowance to how much the yarn stretches. The stitch matters too, so a swatch is the best test: measure it relaxed, then stretched to the size of a head. If you are between two sizes, the Craft Yarn Council’s ranges tell you which side you are on: a head measuring 22 inches, for example, falls in both the woman and the man ranges, and a 2-inch allowance gives a 20-inch hat.

How many stitches and rounds does a crochet hat need?

Four numbers come from your gauge swatch. Gauge, as Oombawka Design defines it, is how many stitches and rows fit in a set measurement, usually 4 inches (10 cm). Work a swatch in the stitch and yarn you plan to use, in the round if you can, measure it after resting, and divide by 4 to get stitches per inch (s) and rounds per inch (r).

The method, step by step:

  1. Hat circumference, C = head circumference minus the negative ease (2 inches for acrylic, 1 for cotton).
  2. Stitches around, N = C multiplied by s. For the final round of the crown and for the sides.
  3. Crown diameter, D = C divided by 3.14 (Oombawka Design’s formula; its example is 21 inches divided by 3.14, which is 6.68 inches). This is the width the flat circle of the top must reach before you stop increasing.
  4. Crown rounds, R = D divided by 2, multiplied by r. Each round adds one row-height to the circle’s radius.
  5. Increase per round = N divided by R, which works out as about 2 times pi times s divided by r, roughly 6.3 times (s over r). If single crochet stitches are about as tall as they are wide, that gives 6, the number Sarah Maker gives for single crochet; hdc gives 8 and double crochet 12, because the taller stitches need more increases.
  6. Round to a multiple of the increase. Sarah Maker’s rule is that each round adds the same number of stitches you made in the ring, so round n has the starting number times n stitches: 6, 12, 18 in single crochet. Pick the nearest multiple of 6 (or 8, or 12) to N, then let yarn, hook and stitch pattern settle the last inch.
  7. Work even. Once the crown reaches D, stop increasing and work rounds without increases until the hat is as tall as you want (next section).

The Craft Yarn Council’s 2018 gauge guidelines give a sense of the range for s in single crochet over 4 inches: 8 to 11 stitches for Bulky (5), 11 to 14 for Medium (4) and 12 to 17 for Light (3) yarn, which is 2 to 2.75, 2.75 to 3.5 and 3 to 4.25 stitches per inch. These are guidelines only; your own swatch decides. For an adult medium hat, 21 inches around, that means about 42 to 58 stitches around in bulky yarn, 58 to 74 in medium and 63 to 89 in light.

Worked example: single crochet at 3 stitches and 3 rounds per inch

Suppose your swatch gives 3 stitches and 3 rounds per inch (12 and 12 over 4 inches, inside the Medium range above). Then every size follows from the same arithmetic. The table uses Oombawka Design’s head circumferences and the 2-inch negative ease.

SizeHeadHat circumference CCrown diameter DStitches around N (C x 3)Crown rounds, 6 per round (N / 6)
Preemie12 in10 in3.18 in305
Newborn14 in12 in3.82 in366
0 to 3 months16 in14 in4.46 in427
3 to 6 months17 in15 in4.77 in457 or 8 (42 or 48 stitches)
6 to 12 months18 in16 in5.09 in488
1 to 3 years19 in17 in5.41 in518 or 9 (48 or 54 stitches)
3 to 5 years20 in18 in5.73 in549
6 to 10 years21 in19 in6.05 in579 or 10 (54 or 60 stitches)
Adult small22 in20 in6.37 in6010
Adult medium23 in21 in6.68 in6310 or 11 (60 or 66 stitches)
Adult large24 in22 in7.00 in6611

The check works: at 3 stitches and 3 rounds per inch, the N divided by 6 count and the D divided by 2 times 3 count agree to within about half a round (for the adult medium, 10.5 and 10.0). Where N falls halfway between two multiples of 6, choose the smaller for a snugger hat in a stretchy yarn and the larger in a stiff or non-stretchy one; at 3 stitches per inch, one round of 6 stitches is 2 inches of circumference.

With half double crochet or double crochet, the same steps give a different round count: divide N by 8 or by 12 instead of 6 (the Sarah Maker numbers), and use your own s and r. The s and r of a swatch change the result, so do not copy a stitch count from another hat unless your gauge matches.

How do you know when the crown is the right size?

Stop increasing when the flat circle measures D across and lies flat. Sarah Maker’s flat circle guide gives the diagnosis: a circle that ruffles has too many stitches (or is worked too loosely), and one that curls into a bowl has too few (or is worked too tightly). If it ruffles, pull back a round and increase a little less; if it cups before it reaches D, increase a little more or move to a larger hook. A slight cup at the very end is normal, because the sides are about to go up.

How tall should a crochet hat be?

Choose the height from how the hat will sit: Oombawka Design gives three. A mid ear hat sits slightly above the bottom of the ears for a close-fitting beanie, a base of ear hat extends to the bottom of the ears and is her choice for an everyday beanie, and a slouch hat has extra length above the crown. For an adult medium, her heights are 7.5, 8.75 and 11 inches.

To estimate the rounds you still need after the crown, subtract half the crown diameter from the target height and multiply by rounds per inch: (height minus D divided by 2) times r. For an adult medium base-of-ear beanie, 8.75 minus 3.34 is 5.41 inches, or about 16 rounds at 3 rounds per inch. This is an estimate, since the crown curves; measure from the center of the crown as you go and stop when the hat is tall enough, and add the brim you plan to fold.

How much yarn does a crochet hat need?

It depends on the weight, the stitch and the size, so read the yarn amount off the pattern. As an example of a published figure, Left in Knots’ free beanie in bulky (5) yarn, with a 6 mm (J) hook, lists 60 to 110 yards depending on the size, from baby to adult, with finished measurements (height by width) of 5.5 by 7 inches for a baby and 8.5 by 11 inches for an adult, and Oombawka Design’s free half double crochet beanie, in medium (4) yarn on a 5.5 mm (I-9) hook, comes in eleven sizes from preemie to adult large. For the yarn weight categories and hook sizes, see our yarn weights explained and crochet hook size chart.

Where can you find a free crochet hat pattern in your size?

These patterns are the designers’ own, free to read at the time of writing:

If the stitches in those patterns are new, our guides to single crochet, half double crochet and the magic ring, which starts the crown, explain each one. Planning a larger project from a size and a yarn count? Our crochet blanket sizes guide uses the same logic for blankets.

Key facts

FAQ

What size crochet hat fits an adult?

The Craft Yarn Council lists adult head circumferences of 21 to 23 inches for a woman and 22 to 24 inches for a man. With 2 inches of negative ease in acrylic yarn, the finished hat is about 19 to 21 inches around for a woman and 20 to 22 for a man; measure the actual head to be sure.

How much smaller should a crochet hat be than the head?

Oombawka Design allows 2 inches of negative ease for medium (4) and DK (3) acrylic, which stretches, and about 1 inch for less stretchy yarn such as cotton. Fabric that stretches less needs less allowance, so check your swatch.

How do you measure a head for a crochet hat?

Put a flexible tape measure across the forehead and around the widest part of the head, snug but not tight, as the Craft Yarn Council and Oombawka Design describe. Note the number in inches; that is the head circumference you subtract the negative ease from.

How many stitches do you start a crochet hat with?

In a magic ring, 6 stitches for single crochet, 8 for half double crochet and 12 for double crochet, adding the same number each round, according to Sarah Maker. The number you finish the crown with depends on your gauge: the hat circumference multiplied by your stitches per inch.

What is the head circumference of a baby?

The Craft Yarn Council gives 14 to 16 inches for a baby and 9 to 12 for a preemie. Oombawka Design's chart is finer, with 14 inches for a newborn, 16 for 0 to 3 months, 17 for 3 to 6 months and 18 for 6 to 12 months.

Sources

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