Shopper measuring head for cap size

Measure in cm First: Find Your Cap Size, Then Shop BluBaazar

Measure your head circumference in centimetres where the sweatband will sit, roughly 1 to 2.5 centimetres above your eyebrows and the tops of your ears, then match that number against the specific brand’s chart, not a generic label. Adjustable caps give you more room to work with, since the strap or snapback covers a wider range.

TL;DR:

  • Measurement placement is crucial; measure head circumference 1 to 2.5 centimeters above the eyebrows and ears for an accurate fit.
  • Most adult men wear sizes between 55 and 60.5 centimeters, with conversions to US fitted sizes and letter labels showing some variability.
  • For fitted caps, match your exact centimetre measurement to the brand’s chart and round up if between sizes; stretch-fit caps require only a size range.
  • Adjustable caps typically fit heads from about 56 to 60 centimeters, but always check the product’s stated size range to ensure a proper fit.
  • Reading brand-specific charts is essential because sizing systems differ: New Era rounds up, Nike groups sizes into broader ranges, and labels may not match your actual measurement.
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Table of Contents

Quick reference: cm, inches, US fitted fractions and letter sizes

Centimetres are the one measurement that stays constant across brands, which is why we lead with that column before translating into anything else. Inches, US fitted fractions and letter sizes all derive from the same circumference, but the labels attached to them shift from one maker to another.

Most adult men fall somewhere between 55 and 60.5 centimetres, according to New Era’s sizing chart, which lists fitted sizes running from size 7 at 55.8 centimetres through size 8 at 63.5 centimetres, with eighth-size steps in between (7⅛ sits at 56.8 centimetres). A separate conversion table from Hatsizecharts lines up the systems directly: 56 centimetres equals 22 inches, a US fitted 7, and a letter size M; 58 centimetres equals 22⅞ inches, a US fitted 7¼, and a letter size L; 60 centimetres equals 23⅝ inches, a US fitted 7½, and a letter size XL.

Centimetres Inches US fitted Letter size
56 cm 22 in 7 M
58 cm 22⅞ in 7¼ L
60 cm 23⅝ in 7½ XL

Letter sizes are the least precise of the four systems because “M” or “L” can cover a span of several centimetres depending on the brand, and two brands rarely use identical cutoffs. When you have an exact centimetre figure, prefer it or the matching fitted fraction over a letter size whenever a product page offers the choice.

How to measure your head correctly

Getting a usable number takes under a minute, but the placement of the tape matters more than people expect.

  1. Wrap a flexible tape measure around your head where the cap’s sweatband will actually rest: about 1 to 2.5 centimetres above your eyebrows and just above the tops of your ears, as described in guidance from both New Era and Nike.
  2. Keep the tape level all the way round, snug against your skin but not pulled tight.
  3. Take the measurement two or three times and use the largest consistent reading.
  4. If you do not have a tape measure, wrap a piece of string instead and measure the string against a ruler.
  5. Measure with your hair in the state you will actually wear it under the cap, and avoid measuring straight after exercise or a hot shower, when your head can be temporarily warmer or your hair unusually flattened, a point echoed in Ribcap’s size guide.

Pro Tip: Measure in the evening and again the next morning if you can; small swelling differences through the day can shift your reading by half a centimetre.

Reading brand charts and converting between systems

Once you have a centimetre figure, converting it is simple arithmetic, but applying it correctly depends on which brand’s chart you are using.

  • To go from centimetres to inches, divide by 2.54; a 58 centimetre head comes to roughly 22.8 inches.
  • US fitted fractions are derived from the diameter of the circle that circumference would form, found by dividing the circumference by pi; a 58 centimetre measurement lands close to a US 7¼ fitted size, matching the hatsizecharts.com conversion table.
  • Brands round differently when you fall between sizes: New Era recommends rounding up for fitted caps, while Nike’s guidance suggests sizing down for a tighter feel or up for a looser one, depending on your preference.
  • A printed “CM” figure on a label does not always equal your actual head circumference. New Era is explicit about this inconsistency across product lines, so always check the chart for the specific cap rather than assuming the number on the tag matches the measurement you took.

Choosing your size by cap style: fitted, stretch-fit and adjustable

Not every cap style needs the same precision, and knowing which ones forgive a slightly off measurement saves you a return.

  • Fitted caps need the exact size that matches your measured circumference; if you fall between two fitted fractions, follow the brand’s own rounding rule, which is usually to round up.
  • Stretch or flex-fit caps work off a letter-size range, so pick whichever range includes your centimetre figure rather than hunting for an exact match.
  • Adjustable styles, including snapbacks and strapbacks, rely on their closure to cover a spread of head sizes; a “one size” claim typically spans roughly 56 to 60 centimetres, so check the product’s stated range before assuming it fits everyone.
  • Specialty hats, such as stiff fedoras or straw hats, have far less give in the crown, so when you are between sizes it usually pays to size up rather than squeeze into the smaller option.

Fit troubleshooting and simple fixes

A cap that looks right on the shelf can still feel wrong once it is on your head, and most problems have a quick fix rather than requiring a return.

Check that the front sits about one finger-width above your eyebrows, that it does not leave lasting red marks after half an hour, and that it sits level without pressing or sliding, fit cues outlined in Ribcap’s guide. A cap that is too loose can often be tightened with a strap adjustment, a hat reducer strip, or a thicker sweatband insert, while a fitted cap that is consistently slipping may need the next size down. A cap that is too tight is usually solved by moving up one size, or for fitted styles, up one eighth-size increment, since fitted crowns do not stretch the way flex-fit material does.

Pro Tip: If a cap pinches after only ten minutes, it is too small; genuine fitted-size issues rarely improve with “breaking in”.

Brand charts are not interchangeable, even when the centimetre figures look similar at first glance. New Era’s chart runs in eighth-size fitted increments from 7 (55.8 centimetres) to 8 (63.5 centimetres), with each step covering roughly 0.8 to 1 centimetre, and it explicitly recommends rounding up when your measurement falls between two listed sizes.

Nike’s hats and headwear chart works differently, grouping circumference ranges into S/M, M/L, L/XL and a broader ONE SIZE band, and it measures from a point about 2.5 centimetres above the eyebrows rather than New Era’s 1.3 centimetres. That half-centimetre difference in placement is small, but it can shift which size a borderline measurement falls into, which is exactly why checking the product-specific chart matters more than memorising a single number.

New Era and Nike cap sizing comparison

Crown depth, sweatband construction and whether a cap is structured or unstructured also affect how identical circumference numbers feel in practice, according to aCustomHat’s fit guide. Two caps listed at the same centimetre size from different brands can sit noticeably differently because of these construction details, so when a product page lists crown depth, it is worth comparing it against a cap you already own and like.

Choosing caps by intended use: sport, casual and fashion wear

Start with how the cap will be worn, since that shapes which style and fit priority matters most. For sport or active use, an adjustable or flex-fit style with moisture-wicking material tends to suit better than a rigid fitted crown, since you want a secure fit that survives movement without pressure points building up over hours.

For everyday casual wear, a dad hat or adjustable snapback gives the most flexibility, since the strap or closure absorbs small measurement errors and the softer, unstructured crown is comfortable across longer wear.

For fashion-first pieces, fit precision matters more because structured, fitted caps are designed to sit close to the head with a defined shape, so an exact centimetre match against the brand’s fitted chart avoids both an awkward gap at the back and a crown that looks pinched. In each case, match the style to the activity first, then use the sizing steps above to narrow down the exact number or range for that specific product.

Return and exchange policies for cap sizing issues

Even a careful measurement can end in a cap that does not sit quite right once it arrives, which is why checking a seller’s return window before ordering is worth the extra minute. Look specifically for whether exchanges are offered for a different size at no extra cost, whether the original packaging or tags need to stay intact, and how many days you have from delivery to start a return.

Fitted caps are sometimes excluded from standard returns once worn, since the sweatband can show signs of use quickly, so trying one on briefly indoors, rather than wearing it outside, keeps your options open if the size is wrong. Keeping the original box or tag attached until you are confident in the fit is a simple habit that avoids disputes later, and checking a product’s specific size notes before ordering reduces the odds you will need a return at all.

Choosing caps for children versus adults

Children’s head circumferences vary more by age than adult sizes do, so a size chart built for adults will not translate directly. A younger child’s head might measure anywhere from around 48 to 54 centimetres, while older children and young teens can already overlap with smaller adult fitted sizes, so checking a youth-specific chart rather than guessing down from an adult size avoids a cap that is loose enough to slide.

Adjustable styles tend to suit children better than fitted ones, since growth makes an exact fitted match short-lived and a strap or snapback closure adjusts as needed over a school year or season. For both children and adults, the same measuring method applies: tape around the head where the cap will sit, snug but not tight, with the main difference being that children’s measurements should be rechecked more often given how quickly head size can change at younger ages.

Child adjusting an adjustable cap

Why a curated catalogue makes buying easier once you’ve measured

Once you know your centimetre measurement, shopping gets a lot simpler with a marketplace that sources products thoughtfully and lists sizing details clearly. We built our catalogue to pair curated, quality-checked items with the product information shoppers actually need to buy with confidence.

— Mr

Where to buy: browsing BluBaazar with your measurement in hand

With your centimetre figure ready, head to our collections page to browse categories including clothing and accessories alongside sizing notes on each listing.

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FAQ

How do I know my cap size?

Measure your head circumference in centimetres with a flexible tape, placed about 1 to 2.5 centimetres above your eyebrows and the tops of your ears, then match that figure against the specific brand’s chart.

What are the UK cap sizes?

UK cap sizes are typically expressed using the same fitted fractions and letter sizes used elsewhere, such as 7 and 7¼ for fitted caps or S/M, M/L and L/XL for adjustable styles, according to Sizeguide. Because brand charts can differ, it is worth checking the seller’s own stated system rather than assuming a UK label maps identically across every brand.

How do I know what size cap I need?

Start with a centimetre measurement of your head taken where the cap’s sweatband will sit, then compare it to the specific product’s chart rather than a generic size guide. Fitted caps need an exact match, while adjustable and stretch-fit styles only need your measurement to fall within the listed range.

Is a 57cm head big?

A 57 centimetre head sits comfortably within the common adult range, close to a US fitted size 7⅛ based on conversion tables from hatsizecharts.com. It is neither unusually small nor unusually large, and most adult fitted and adjustable caps will offer a size or range that covers it.

Sources

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