Hat size calculator
Enter your head measurement, or drag the tape. You get your US size and your size on every brand chart we have checked, with the brand's own numbers and a link to where they came from.
By Fitness Hats Editorial Team, published October 7, 2026. Brand charts checked October 4, 2026
58.0 cm is 22.83 in. Drag the tape or use the arrow keys to adjust.
US hat size
7 1/4
head diameter in inches, nearest 1/8
| Brand and line | Your size | The chart lists | Source |
|---|---|---|---|
| '47Adjustable caps | WOMEN or OSFAThe published ranges for these sizes overlap at your measurement. | WOMEN: 21 1/2 to 23 1/2 in, 55 to 59 cmOSFA: 22 to 24 in, 56 to 61 cm | '47 chartchecked 2026-10-04 |
| adidasHats and caps | Adult (S/M) or Adult (M/L)The published ranges for these sizes overlap at your measurement. | Adult (S/M): 22 to 22.8 in, 56 to 58 cmAdult (M/L): 22.8 to 23.6 in, 58 to 60 cm | adidas chartchecked 2026-10-04 |
| Arc'teryxHats and caps | One-size-fits-all or L - XLThe published ranges for these sizes overlap at your measurement. | One-size-fits-all: 21 3/4 to 23 1/2 in, 55 to 60 cmL - XL: 22 3/4 to 23 1/2 in, 58 to 60 cm | Arc'teryx chartchecked 2026-10-04 |
| Boco GearHats | OSFM or XLThe published ranges for these sizes overlap at your measurement. | OSFM: 55 to 59 cmXL: 58 to 61 cm | Boco Gear chartchecked 2026-10-04 |
| Ciele AthleticsGOCap, FSTCap and TRLCap | S/M or M/L or L/XLThe published ranges for these sizes overlap at your measurement. | S/M: 53.5 to 59 cmM/L: 55 to 61 cmL/XL: 57 to 63 cm | Ciele Athletics chartchecked 2026-10-04 |
| FlexfitStandard stretch-fit | S/M or OSFA or L/XLThe published ranges for these sizes overlap at your measurement. | S/M: 21 1/4 to 22 3/4 in, 54 to 58 cmOSFA: 21 5/8 to 23 1/2 in, 55 to 60 cmL/XL: 22 3/8 to 23 7/8 in, 57 to 61 cm | Flexfit chartchecked 2026-10-04 |
| FlexfitDELTA (stretch-fit) | S/M or L/XLThe published ranges for these sizes overlap at your measurement. | S/M: 21 1/4 to 22 3/4 in, 54 to 58 cmL/XL: 22 3/8 to 23 7/8 in, 57 to 61 cm | Flexfit chartchecked 2026-10-04 |
| Flexfit210 (stretch-fit) | S/M or L/XLThe published ranges for these sizes overlap at your measurement. | S/M: 21 5/8 to 22 3/4 in, 55 to 58 cmL/XL: 22 3/4 to 23 7/8 in, 58 to 61 cm | Flexfit chartchecked 2026-10-04 |
| Flexfit110 (adjustable) | OSFA | OSFA: 20 3/8 to 24 5/8 in, 52 to 63 cm | Flexfit chartchecked 2026-10-04 |
| HeadsweatsLarge Running Hat | Large | Large: 57 to 63 cm | Headsweats chartchecked 2026-10-04 |
| King & FifthAdjustable caps | S/M | S/M: 21 3/4 to 22 3/4 in, 55.1 to 58 cm | King & Fifth chartchecked 2026-10-04 |
| King & FifthThe Jack (fitted) | M | M: 22 1/2 to 23 1/8 in, 57 to 58.9 cm | King & Fifth chartchecked 2026-10-04 |
| Lamood Big HatsSize chart | 7 1/4 | 7 1/4: 22 3/4 to 22 7/8 in, 57.8 to 58.1 cm | Lamood Big Hats chartchecked 2026-10-04 |
| lululemonHats in S/M and L/XL | S/M or L/XLThe published ranges for these sizes overlap at your measurement. | S/M: 20.06 to 23 1/4 in, 51 to 59 cmL/XL: 22.44 to 24 3/8 in, 57 to 64 cm | lululemon chartchecked 2026-10-04 |
| lululemonHats in XS to XL | L | L: 22.44 to 23 1/4 in, 57 to 59 cm | lululemon chartchecked 2026-10-04 |
| Mammoth HeadwearRegular and XXL caps | Smaller than this chartSmallest listed: Regular Size (24 1/4 to 26 7/8 in, 61.4 to 68.3 cm). | Mammoth Headwear chartchecked 2026-10-04 | |
| MelinSize guide (all caps) | SMALL | SMALL: 22 to 22 5/8 in, 56.5 to 58.5 cm | Melin chartchecked 2026-10-04 |
| New Era59FIFTY fitted | 7 3/8Between 7 1/4 and 7 3/8; the brand says to size up. | 7 1/4: 22 3/4 in, 57.7 cm7 3/8: 23 1/8 in, 58.7 cm | New Era chartchecked 2026-10-04 |
| New Era39THIRTY stretch-fit | S/M | S/M: 22 3/8 to 23 1/8 in, 56.8 to 58.7 cm | New Era chartchecked 2026-10-04 |
| New Era9FIFTY snapback | S/M or One Size or M/LThe published ranges for these sizes overlap at your measurement. | S/M: 21 5/8 to 23 1/2 in, 54.9 to 59.6 cmOne Size: 22 3/8 to 24 5/8 in, 56.8 to 62.5 cmM/L: 22 3/8 to 24 5/8 in, 56.8 to 62.5 cm | New Era chartchecked 2026-10-04 |
| New Era9FORTY adjustable | One Size | One Size: 22 to 23 7/8 in, 55.8 to 60.6 cm | New Era chartchecked 2026-10-04 |
| New Era9TWENTY and Casual Classic | One Size Fits Most | One Size Fits Most: 22 to 23 7/8 in, 55.8 to 60.6 cm | New Era chartchecked 2026-10-04 |
| NikeAdjustable caps | M/L or ONE SIZE or L/XLThe published ranges for these sizes overlap at your measurement. | M/L: 21 1/2 to 23 1/2 in, 55 to 60 cmONE SIZE: 21 1/2 to 23 1/2 in, 55 to 60 cmL/XL: 22 5/8 to 24 5/8 in, 58 to 63 cm | Nike chartchecked 2026-10-04 |
| NikeSwoosh Flex (stretch-fit) | M/L | M/L: 21 7/8 to 23 in, 56 to 59 cm | Nike chartchecked 2026-10-04 |
| OnCaps (one size) | ONE SIZE | ONE SIZE: 21.7 to 23.6 in, 55 to 60 cm | On chartchecked 2026-10-04 |
| OnCaps in S/M and L/XL | L/XL | L/XL: 21.7 to 23.6 in, 55 to 60 cm | On chartchecked 2026-10-04 |
| PatagoniaHats (all styles) | One Size or Large/X-LargeThe published ranges for these sizes overlap at your measurement. | One Size: 21 3/4 to 24 inLarge/X-Large: 22 3/4 to 24 in | Patagonia chartchecked 2026-10-04 |
| RichardsonFitted | 7 1/4 | 7 1/4: 22 3/4 in, 58 cm | Richardson chartchecked 2026-10-04 |
| RichardsonR-Flex (stretch-fit) | SM-MD | SM-MD: 22 to 22 3/4 in, 56 to 58 cm | Richardson chartchecked 2026-10-04 |
| RichardsonAdjustable | OSFM & MD-LG or XLThe published ranges for these sizes overlap at your measurement. | OSFM & MD-LG: 22 to 24 1/4 in, 56 to 62 cmXL: 22 3/4 to 24 5/8 in, 58 to 63 cm | Richardson chartchecked 2026-10-04 |
| RichardsonSystem 5 (PTS75) | MD | MD: 22 3/8 to 22 3/4 in, 57 to 58 cm | Richardson chartchecked 2026-10-04 |
| Under ArmourMen's and unisex headwear | OSFM or M/L or L/XLThe published ranges for these sizes overlap at your measurement. | OSFM: 21 5/8 to 23 7/8 in, 54.9 to 60.6 cmM/L: 22 to 23 1/4 in, 55.9 to 59.1 cmL/XL: 22 3/4 to 24 in, 57.8 to 61 cm | Under Armour chartchecked 2026-10-04 |
| Under ArmourHat size table | 7 1/4 or 7 3/8Between 7 1/4 and 7 3/8; the brand does not say which way to go. | 7 1/4: 22 3/4 in, 57.8 cm7 3/8: 23 1/8 in, 58.7 cm | Under Armour chartchecked 2026-10-04 |
The calculator opens on an example head of 58.0 cm; replace it with yours.
How the calculator works
The US size is the hatter's convention: the head's diameter in inches, which is the circumference divided by pi, rounded to the nearest eighth. A 58.0 cm head is 22.83 in around, and 22.83 divided by pi is 7.27, so it is a 7 1/4 (source: Wikipedia, Hat: Size). Brands round their own charts a little differently, which is why the brand rows matter more than this number.
The brand rows come from each brand's own size chart, copied exactly, with the page we read and the date we checked it. A fitted chart lists one head size per label. When your head falls between two labels, you see both, unless the brand says which way to go. Stretch-fit and adjustable charts list ranges; where two ranges overlap, you see both sizes.
A chart tells you the head a hat is made for, not how big a particular hat is inside. Two hats with the same label can differ.
The charts behind it
Every chart in the calculator, where we read it and when.
| Brand | Chart | Sizes | Checked |
|---|---|---|---|
| '47 | Adjustable caps | WOMEN, OSFA | 2026-10-04 |
| adidas | Hats and caps | Adult (S/M), Adult (M/L), Adult (L/XL) | 2026-10-04 |
| Arc'teryx | Hats and caps | S - M, L - XL, One-size-fits-all | 2026-10-04 |
| Boco Gear | Hats | Women, OSFM, XL | 2026-10-04 |
| Ciele Athletics | GOCap, FSTCap and TRLCap | S/M, M/L, L/XL | 2026-10-04 |
| Flexfit | Standard stretch-fit | OSFA, S/M, L/XL, XXL | 2026-10-04 |
| Flexfit | DELTA (stretch-fit) | S/M, L/XL | 2026-10-04 |
| Flexfit | 210 (stretch-fit) | S/M, L/XL | 2026-10-04 |
| Flexfit | 110 (adjustable) | OSFA | 2026-10-04 |
| Headsweats | Large Running Hat | Large | 2026-10-04 |
| King & Fifth | Adjustable caps | XS, S/M, L/XL, XXL | 2026-10-04 |
| King & Fifth | The Jack (fitted) | XS, S, M, L, XL, XXL | 2026-10-04 |
| Lamood Big Hats | Size chart | 7 1/4, 7 3/8, 7 1/2, 7 5/8, 7 3/4, 7 7/8, 8, 8 1/8, 8 1/4, 8 3/8, 8 1/2, 8 5/8, 8 3/4, 8 7/8, 9, 9 1/8, 9 1/4 | 2026-10-04 |
| lululemon | Hats in S/M and L/XL | S/M, L/XL | 2026-10-04 |
| lululemon | Hats in XS to XL | XS, S, M, L, XL | 2026-10-04 |
| Mammoth Headwear | Regular and XXL caps | Regular Size, XXL Size | 2026-10-04 |
| Melin | Size guide (all caps) | SMALL, CLASSIC, XL | 2026-10-04 |
| New Era | 59FIFTY fitted | 6 7/8, 7, 7 1/8, 7 1/4, 7 3/8, 7 1/2, 7 5/8, 7 3/4, 7 7/8, 8 | 2026-10-04 |
| New Era | 39THIRTY stretch-fit | S/M, M/L, L/XL | 2026-10-04 |
| New Era | 9FIFTY snapback | S/M, One Size, M/L, L/XL | 2026-10-04 |
| New Era | 9FORTY adjustable | One Size | 2026-10-04 |
| New Era | 9TWENTY and Casual Classic | One Size Fits Most | 2026-10-04 |
| Nike | Adjustable caps | S/M, M/L, L/XL, ONE SIZE | 2026-10-04 |
| Nike | Swoosh Flex (stretch-fit) | S/M, M/L, L/XL | 2026-10-04 |
| On | Caps (one size) | ONE SIZE | 2026-10-04 |
| On | Caps in S/M and L/XL | S/M, L/XL | 2026-10-04 |
| Patagonia | Hats (all styles) | One Size, Small/Medium, Large/X-Large | 2026-10-04 |
| Richardson | Fitted | 6 3/8, 6 1/2, 6 5/8, 6 3/4, 6 7/8, 7, 7 1/8, 7 1/4, 7 3/8, 7 1/2, 7 5/8, 7 3/4, 7 7/8, 8 | 2026-10-04 |
| Richardson | R-Flex (stretch-fit) | XS-SM, SM-MD, LG-XL | 2026-10-04 |
| Richardson | Adjustable | SM, OSFM & MD-LG, XL | 2026-10-04 |
| Richardson | System 5 (PTS75) | XS, SM, MD, LG, XL | 2026-10-04 |
| Under Armour | Men's and unisex headwear | OSFM, S/M, M/L, L/XL, XL/XXL | 2026-10-04 |
| Under Armour | Hat size table | 6 5/8, 6 3/4, 6 7/8, 7, 7 1/8, 7 1/4, 7 3/8, 7 1/2, 7 5/8, 7 3/4, 7 7/8, 8, 8 1/8, 8 1/4 | 2026-10-04 |
Left out: '47 Franchise (fitted) ('47 lists XL as 60 to 61 cm but also as 23 3/4 to 24 1/2 in, and 24 1/2 in is about 62.2 cm, so its inch and cm columns disagree); Brooks Hats (Brooks lists L/XL as 21 to 23 in but 54 to 60 cm, and 23 in is 58.4 cm); New Era Women's 9TWENTY and Casual Classic (New Era's page pairs 21 1/4 to 23 7/8 in with 53.9 to 58.7 cm, but 23 7/8 in is 60.6 cm everywhere else on the same page); Pacific Headwear True fitted (Pacific's chart steps 3/8 in between most sizes, but lists 7 5/8 as 23 3/4 in and 7 3/4 as 24 1/2 in, so its inch and cm columns disagree there); Sprints Adult hats (one size) (Sprints gives 22.8 to 24.3 in and calls that hat size 6 1/4 to 7 7/8, but 22.8 in is about a 7 1/4 by the size convention); Under Armour Women's headwear (Under Armour's women's chart lists OSFM as 20 7/8 to 22 1/8 in but 53 to 58.7 cm, and 58.7 cm is 23 1/8 in).
We also checked American Needle, Bandit Running, Gymshark, Janji, Mitchell & Ness, New Balance, Oakley, Puma, Tracksmith, Vuori. None of them publishes a head-size chart for its caps on its own site, so they are not in the calculator.
Frequently asked questions
What size hat is a 23 inch head?
A 23 inch head is 58.4 cm, which is US size 7 3/8 by the convention (23 divided by pi, to the nearest eighth). On fitted charts: King & Fifth The Jack (fitted): M; Lamood Big Hats Size chart: 7 3/8; New Era 59FIFTY fitted: 7 3/8 (between 7 1/4 and 7 3/8; New Era says to round up); Richardson Fitted: 7 3/8 (between 7 1/4 and 7 3/8; Richardson says to round up); Under Armour Hat size table: between 7 1/4 and 7 3/8.
What size is a 7 1/4 hat in cm?
By the US convention (head diameter in inches), 7 1/4 is a 22.78 in or 57.9 cm head. Lamood Big Hats Size chart lists 7 1/4 for a 22 3/4 to 22 7/8 in, 57.8 to 58.1 cm head; New Era 59FIFTY fitted lists 7 1/4 for a 22 3/4 in, 57.7 cm head; Pacific Headwear True fitted lists 7 1/4 for a 22 3/4 in, 58 cm head; Richardson Fitted lists 7 1/4 for a 22 3/4 in, 58 cm head; Under Armour Hat size table lists 7 1/4 for a 22 3/4 in, 57.8 cm head.
What does S/M mean on a hat?
It depends on the brand. Across the 12 charts we checked that use S/M, it covers heads from 51.0 to 59.6 cm. Ciele Athletics GOCap, FSTCap and TRLCap: 53.5 to 59 cm; Flexfit Standard stretch-fit: 21 1/4 to 22 3/4 in, 54 to 58 cm; Flexfit DELTA (stretch-fit): 21 1/4 to 22 3/4 in, 54 to 58 cm; Flexfit 210 (stretch-fit): 21 5/8 to 22 3/4 in, 55 to 58 cm; King & Fifth Adjustable caps: 21 3/4 to 22 3/4 in, 55.1 to 58 cm; lululemon Hats in S/M and L/XL: 20.06 to 23 1/4 in, 51 to 59 cm; New Era 39THIRTY stretch-fit: 22 3/8 to 23 1/8 in, 56.8 to 58.7 cm; New Era 9FIFTY snapback: 21 5/8 to 23 1/2 in, 54.9 to 59.6 cm; Nike Adjustable caps: 20 1/2 to 22 1/4 in, 52 to 57 cm; Nike Swoosh Flex (stretch-fit): 20 7/8 to 21 7/8 in, 53 to 56 cm; On Caps in S/M and L/XL: 20 1/2 to 22.4 in, 52 to 57 cm; Under Armour Men's and unisex headwear: 21 1/4 to 22 1/2 in, 54 to 57.2 cm.
Should I size up or down if I am between sizes?
Follow the brand when it says. New Era: "If you're between sizes, we recommend rounding up." Richardson: "If uncertain about the size or in between sizes, opt for the larger size to ensure a comfortable fit." The other charts here give no advice, so the calculator shows both neighboring sizes for them.