Whether you're buying a fitted baseball cap, a classic fedora, or a beanie, head measurement is key to comfort. Our International Hat Size Converter takes your head circumference in inches or centimeters and instantly provides your corresponding US, UK, and Alpha (S-XXL) sizes. No more tight caps or slipping brims; find your exact fit based on professional millinery standards.
Privacy Protected
International Hat Size Converter
Convert head circumference in inches and centimeters to US, UK, and Alpha (S/M/L) hat sizes. Fast, free, and 100% private. All processing happens locally.
Share Tool
Select files or drag & drop here
Processed 100% locally in your browser. Your files never touch an external server.
Choose File to Begin
100% Client-Side Privacy•No File Size Limits•Free Forever
About International Hat Size Converter
FusioFiles 100% Client-Side Privacy Guarantee
Your files and data never leave your browser — processed directly on your device.
Zero Server UploadsExecution occurs entirely in browser memory via WebAssembly and HTML5 Canvas.
HIPAA & GDPR ReadySafe for confidential tax forms, medical records, financial sheets, and legal contracts.
Zero Cloud LatencyInstant results with no upload delays, server queues, or third-party tracking.
Automatic RAM PurgeBuffers and caches are automatically wiped clean the instant you close the tab.
1
Wrap Tape
Wrap a measuring tape around your head just above the ears.
2
Convert
Input the measurement to see your fitted and alpha hat sizes.
3
Review Results
Verify the output looks correct before using or downloading it.
4
Save Your Output
Click the download or copy button to export your results to your device or clipboard.
Key Features
Circumference to Size
Translates raw head measurements directly into fitted hat numbers.
US vs UK Standards
Accounts for the subtle sizing differences between American and British headwear manufacturers.
Alpha Scaling
Includes S, M, L, and XL mappings for flexible caps and winter hats.
Frequently Asked Questions
No, UK hat sizes are slightly smaller than US sizes for the same circumference.
Related Tools
View allLast updated on