Skip to content
  1. We support GOVX discountslearn more
Hands measuring head circumference with tape

Hat Sizing Guide: Measure Right, Fit Right

Aug 07, 2026

Wrap a soft measuring tape around your head where a hat naturally sits — about 1 inch above your eyebrows, level above your ears, and around the largest part of the back of your skull — then read the circumference in inches. That single number tells you everything. A 23-inch measurement corresponds to a Large (L) alpha range hat size based on common conversion charts. If your number lands between two sizes, choose the size that offers a more comfortable fit.

Table of Contents

How to use a hat sizing guide to measure correctly

Getting an accurate measurement takes about two minutes, and doing it right the first time saves you a return trip. According to hat-sizing standards, the correct position is 1 inch above the eyebrows, level across the top of the ears, and around the widest point at the back of the skull.

What you need:

  • A soft cloth or flexible plastic measuring tape (the kind used for sewing)
  • A mirror, or a second person to check the tape is level
  • A pen and paper to record both inches and centimeters

Steps:

  1. Stand in front of a mirror and position the tape 1 inch above your eyebrows.
  2. Run the tape level around your head, keeping it just above both ears.
  3. Wrap it around to the widest part of the back of your skull.
  4. Keep the tape snug against your head but not pressing in.
  5. Read the measurement where the tape overlaps. Record it in both inches and centimeters.
  6. Measure a second time and use the larger of the two readings.

One detail many people miss: measure over the hair volume you typically wear to ensure a comfortable fit.

Pro Tip: Fitted caps increase in 1/8-inch steps. If your measurement is 22 3/4 inches, round up to the nearest eighth-inch mark — 22 7/8 — before checking the conversion chart. That single eighth of an inch is the difference between a hat that sits right and one that leaves a red ring.

What to do when you don’t have a measuring tape

No sewing tape on hand? A non-stretch string, a shoelace, or even a strip of paper works just as well. Wrap it around your head using the same landmarks: 1 inch above the eyebrows, level above the ears, around the widest point at the back.

Hands wrapping string to measure head

Mark the overlap point with a pen or pinch it with your fingers, then lay the string flat against a ruler or yardstick and read the length. That number is your head circumference.

One warning: never use elastic cord, stretchy ribbon, or rubber bands. They compress against your head and give you a reading that’s smaller than your actual circumference, which means you’ll order a hat that’s too tight. A firm, non-stretch string is the only reliable substitute.

Repeat the measurement twice. If the two readings differ by more than 1/4 inch, take a third measurement and average the closest two. Small inconsistencies in string tension are common, and averaging removes that error.

Hat size conversion chart: inches, cm, US, UK, EU, and alpha

Fitted hat numeric sizes are calculated by dividing head circumference by π (approximately 3.14159). A 22-inch circumference divided by π gives roughly 7.0, which is US size 7. Sizes increase in 1/8-inch steps from there, which is why the chart below moves in small, precise increments.

Hat size conversion chart infographic

Head Circ. (in) Head Circ. (cm) US Numeric UK Size EU Size Alpha Style Note
— — 6 5/8 6 5/8 — XS Fitted only; rare in adjustable
21 1/8 —.7 6 3/4 6 3/4 — XS Fitted; some stretch-fit S/M
21 5/8 —.9 6 7/8 6 7/8 — S Fitted and stretch-fit S
22 —.9 7 7 56 S Common fitted size
22 3/8 — 7 1/8 7 1/8 — M Fitted; snapback mid-range
22 7/8 — 7 1/4 7 1/4 — M Most common adult size
23 —.4 7 3/8 7 3/8 59 L Fitted and stretch-fit M/L
23 1/2 — 7 1/2 7 1/2 — L Common in adjustable hats
23 7/8 —.6 7 5/8 7 5/8 — XL Fitted; some stretch-fit L/XL
— —.9 7 3/4 7 3/4 — XL Fitted; larger adjustable range
— —.9 7 7/8 7 7/8 — XXL Fitted only; check brand chart
— —.8 8 8 64 XXL Fitted; rare in standard stock

Reading the chart: A 22-inch head is US size 7, EU 56, alpha S. A 23-inch head is US 7 3/8, EU 59, alpha L. Brand-specific charts like New Era’s 59FIFTY line map these exact measurements to their fitted sizing, and they advise sizing up whenever your measurement falls between two increments.

Most adult head circumferences cluster in a mid-range typical of medium to large hat sizes.

How hat style changes the fit even when your size stays the same

Your circumference number is fixed. How a hat feels on your head is not. Crown structure, panel count, and closure type all change the fit experience, sometimes by a full size.

Fitted caps (structured, no closure) are the most precise. The numeric size is your measurement divided by π, rounded to the nearest 1/8 inch. There’s no adjustment room, so accuracy matters most here.

Stretch-fit caps (Flexfit and similar) use elasticated fabric that covers a range, typically S/M for heads 21.5–22.5 inches and L/XL for 22.5–23.5 inches. They’re forgiving, but a head at the very top of a range may find the crown sits high.

Snapbacks and strapbacks are adjustable and generally fit heads from about 21.5 to 23.5 inches. The Fire Things Snapback Hat from Brass & Bunker Co is a good example of this style: the snap closure lets you dial in the fit without needing an exact numeric size.

Hand adjusting snapback hat closure

Unstructured dad caps have soft, floppy crowns that conform more easily to head shape. They run slightly larger in feel than a structured cap of the same labeled size.

Beanies are the most forgiving of all. Knit fabric stretches across a wide range, and most adult beanies cover S through XL. The Brass & Bunker Co. Cuffed Beanie fits this pattern: the ribbed knit adapts to your head without needing a precise measurement.

Stiff-brim hats (fedoras, cowboy hats, structured bucket hats) behave more like fitted caps. The rigid crown doesn’t flex, so sizing up when between sizes is especially important here.

What to do when your measurement falls between two sizes

For fitted caps, the rule is simple: round up to the next 1/8-inch size. A head measuring 22 5/8 inches goes to US 7 1/4, not 7 1/8. A hat that’s slightly large can be adjusted; one that’s too small cannot.

For adjustable hats, check the stated fit range on the product page. If your measurement sits in the middle of the range, you’re in the sweet spot. If you’re near the top of the range, consider whether the closure gives you enough room.

When a fitted hat is slightly large, these fixes work well:

Hat sizing tape is a foam or fabric strip that adheres to the inside of the sweatband and reduces the interior circumference by up to 1/4 inch. It’s the cleanest solution and leaves no visible trace.

Foam strips or sweatband inserts add a bit more bulk and are removable, which makes them useful if your head size changes slightly with different hairstyles.

Hat reducers are full-band inserts that sit inside the crown. They work best when a hat is 1/4 to 1/2 inch too large.

When adjustments won’t help: if a structured fitted cap is a full 1/8 size too small, the crown won’t sit at the right depth on your head and no insert will fix that. Exchange it for the correct size.

Pro Tip: Before ordering a fitted cap online, check whether the brand publishes a size chart with exact circumference measurements. Some brands cut slightly large or small within the same numeric label, and a brand-specific chart catches that before the hat ships.

Common measuring mistakes and how to avoid them

Five mistakes account for most wrong-size orders:

  • Pulling the tape too tight. The tape should lie flat against your head, not compress the skin. Tight taping can shave 1/4 to 1/2 inch off your actual circumference.
  • Measuring at the wrong position. Too high on the forehead or too far back on the skull gives a smaller reading than where the hat actually sits.
  • Ignoring hair volume. Measuring against a bare scalp when you normally wear a hat over thick hair means the hat will be too tight in real use.
  • Using stretchy string. As noted above, elastic materials compress and under-report circumference.
  • Misreading fractions. On a standard tape, 1/8-inch marks are small. Confirm you’re reading the correct fraction before recording.

Quick accuracy checklist before you order:

  • Did you measure twice and use the larger reading?
  • Did you compare your measurement to the brand’s own size chart, not just a generic cap size chart?
  • Did you account for crown depth? Deep crowns on structured hats sit lower on the head and can feel tighter than a shallow crown of the same size.
  • Is your head shape more round, oval, or long? Two people with a 23-inch circumference can experience different fits if one has a rounder head and the other has a longer, narrower skull. Oval and long heads often do better in hats with more front-to-back depth in the crown.

Expert hat care tips that keep your fit consistent over time

A hat that fits perfectly on day one can lose that fit after one bad wash. The construction of your hat determines how you should clean it.

First, check the brim. If it’s cardboard, avoid submerging the hat entirely and stick to spot cleaning or a professional cleaner. Cardboard brims warp permanently when soaked. Plastic brims handle moisture far better.

For most baseball caps and structured hats, hand-washing is the safest method. Use cool water, a soft brush on the sweatband, and mild liquid detergent. Rinse thoroughly and reshape the crown by hand before drying.

Laundry scientists advise against bleach and powdered detergents for hats. Both leave residue that weakens fibers over repeated washes, which changes how the hat holds its shape. Mild liquid detergent and cold water preserve material integrity far longer.

If you prefer machine washing, use a hat cage or mesh laundry bag, run the gentlest cycle available, and use cold water only. Never use hot water or a normal spin cycle on a structured cap.

Hat restorers recommend reshaping a damp hat immediately after washing, placing it over a rounded form like a bowl or a hat stand and letting it air-dry completely. Letting a wet hat dry on a flat surface or crumpled in a bag permanently warps the brim and distorts the crown. Never tumble-dry a hat. The heat shrinks the sweatband and can cause the crown to collapse.

For leather patch hats specifically, keep the patch dry during washing. Spot-clean around it with a damp cloth rather than submerging the hat, and condition the leather patch occasionally with a small amount of leather conditioner to prevent cracking.

Key Takeaways

Measure your head circumference where the hat sits, use the conversion chart to find your US numeric size, and always round up when you fall between two fitted sizes.

Point Details
Measure at the right position Place the tape 1 inch above eyebrows, level above ears, around the widest point at the back of the skull.
Round up between fitted sizes If your measurement falls between two 1/8-inch increments, always choose the larger fitted size.
Style affects fit Fitted caps require exact sizing; snapbacks, stretch-fit, and beanies cover a range and are more forgiving.
Protect fit through proper care Hand-wash with mild liquid detergent and cold water; reshape over a rounded form and air-dry immediately.
Brass & Bunker Co hats Check each product page for numeric or alpha sizing, then use this chart to match your measurement before ordering.

Why getting your hat size right is worth the extra two minutes

Most people guess their hat size. They grab a medium because it sounds right, or they order the same size they bought five years ago from a different brand. Then the hat arrives and it either sits too high on the forehead or leaves an impression on the skin after an hour.

The conventional wisdom is that adjustable hats solve this problem. They don’t, not entirely. An adjustable closure handles circumference, but it doesn’t account for crown depth, panel structure, or head shape. A snapback set to the right circumference can still feel wrong on a longer, narrower head because the crown doesn’t have enough front-to-back depth. Circumference is the starting point, not the whole answer.

What actually matters is treating your measurement as a baseline and then reading the style-specific notes. A 23-inch head in a fitted cap is a 7 3/8. That same head in a stretch-fit cap might need an L/XL if the M/L runs short in the crown. The two minutes you spend measuring and cross-referencing the brand chart are the two minutes that separate a hat you wear every shift from one that sits in a drawer.

Gear built for the people who answer the call

Brass & Bunker Co was founded by a firefighter and a product designer who understood that first responders deserve gear that holds up to the job, fits right from day one, and means something when you put it on.

Brass & Bunker Co

Every hat in the Brass & Bunker Co hats collection is labeled with either a numeric size or an alpha size. Use the conversion chart in this guide to match your head circumference to the correct label before you add to cart. For fitted styles like the Logo Hat Gold Stitch Edition, match your circumference to the numeric size exactly. For adjustable styles, check the stated fit range on the product page and confirm your measurement falls within it.

Measuring before checkout takes two minutes and eliminates the guesswork. Browse the full hat collection, find the style that represents your service, and order with confidence knowing the fit is already figured out. While you’re there, the firefighter apparel collection has the rest of the gear to match.

Useful sources

These are the guides and expert sources used to build this hat sizing guide. Each one goes deeper on a specific aspect of measuring, converting, or caring for hats.

Brass & Bunker

Leave a comment