International Hat Sizing Chart — US, UK, EU, JP, AU
A practical hat size conversion reference for buyers, brand owners and procurement managers sourcing custom headwear. Sizes shown in cm and inches with country-specific labels for the US, UK, EU, Japan and Australia, plus a youth and infant sizing table.
How to measure your hat size
Wrap a flexible measuring tape around your head approximately 1 cm (1/2 inch) above the ears and across the middle of the forehead — the natural resting line for a structured cap. Keep the tape level. Snug, not tight. Record in centimeters for the most accurate sizing.
Adult hat sizing — international conversion
| Crown (cm) | Crown (in) | US Fitted | UK | EU | JP | AU | One-Size (S/M/L) |
|---|---|---|---|---|---|---|---|
| 54 | 21 1/4 | 6 3/4 | 6 5/8 | 54 | 54 | 6 3/4 | S |
| 55 | 21 5/8 | 6 7/8 | 6 3/4 | 55 | 55 | 6 7/8 | S |
| 56 | 22 | 7 | 6 7/8 | 56 | 56 | 7 | M |
| 57 | 22 3/8 | 7 1/8 | 7 | 57 | 57 | 7 1/8 | M |
| 58 | 22 7/8 | 7 1/4 | 7 1/8 | 58 | 58 | 7 1/4 | M |
| 59 | 23 1/4 | 7 3/8 | 7 1/4 | 59 | 59 | 7 3/8 | L |
| 60 | 23 5/8 | 7 1/2 | 7 3/8 | 60 | 60 | 7 1/2 | L |
| 61 | 24 | 7 5/8 | 7 1/2 | 61 | 61 | 7 5/8 | L |
| 62 | 24 3/8 | 7 3/4 | 7 5/8 | 62 | 62 | 7 3/4 | XL |
| 63 | 24 3/4 | 7 7/8 | 7 3/4 | 63 | 63 | 7 7/8 | XL |
| 64 | 25 1/4 | 8 | 7 7/8 | 64 | 64 | 8 | XXL |
Youth and infant hat sizing
| Age | Crown (cm) | Crown (in) | US Tag | EU Tag |
|---|---|---|---|---|
| 0-3 months | 38-41 | 15-16 1/4 | Newborn | 38-41 |
| 3-6 months | 42-44 | 16 1/2-17 3/8 | Infant | 42-44 |
| 6-12 months | 44-46 | 17 3/8-18 1/8 | Infant | 44-46 |
| 12-24 months | 46-48 | 18 1/8-18 7/8 | Toddler | 46-48 |
| 2-4 years | 48-50 | 18 7/8-19 5/8 | Toddler | 48-50 |
| 4-7 years | 51-53 | 20 1/8-20 7/8 | Kids S | 51-53 |
| 7-12 years | 53-55 | 20 7/8-21 5/8 | Kids M/L | 53-55 |
| 12-16 years | 55-57 | 21 5/8-22 3/8 | Youth | 55-57 |
Adjustable closures by size range
Custom adjustable hats use a closure mechanism that flexes across a head-size range. Each closure type covers a different range:
- Plastic snap-back (8-snap) — Fits 54-62 cm (US 6 3/4 to 7 3/4). Industry standard for snapback hats and trucker caps.
- Plastic snap-back (6-snap) — Fits 55-61 cm. Smaller range, used on premium retail snapbacks.
- Fabric strap with metal buckle — Fits 54-63 cm. Standard for dad hats, unstructured caps and washed cotton silhouettes.
- Velcro / hook-and-loop — Fits 53-63 cm. Cheapest, widest range, used on promotional and kids' caps.
- Elastic stretch band — Fits 56-60 cm. Used on fitted-style stretchback caps that approximate fitted fit.
- Drawstring (bucket hats) — Fits 53-62 cm depending on shell construction.
Fitted vs adjustable: which to spec?
Fitted caps (no closure, sized 6 7/8 through 8) are stitched to the exact crown measurement and feel more polished, but require buyers to stock multiple SKUs per design. Adjustable caps cover the same range with one SKU at the cost of slightly less precise fit. For e-commerce direct-to-consumer brands, adjustable is standard. For retail-distribution or pro sports licensees, fitted is often preferred. We discuss the tradeoff in detail in our fitted vs adjustable buyer's guide.
Sizing tolerance — how accurate is your hat actually?
Manufacturing tolerance for cap crown circumference is typically ±0.5 cm on retail-grade production and ±1.0 cm on promotional production. A cap labeled 58 cm could measure 57.5-58.5 cm and still pass AQL 2.5 inspection. For premium fitted caps, request a ±0.3 cm tolerance and confirm via approved sample. Our 32-point AQL 2.5 inspection includes crown circumference verification on every shipment.