Topology Manufacturing

Hat & Cap Size Chart & Converter

Enter your head circumference to find your perfect fitted hat size across US, metric, and alpha sizing systems.

Units
cm
US Fitted — fitted size
Alpha Size — S / M / L
Measurement — cm / inches
◈

Enter your measurement above to get a personalised fit recommendation.

Full Size Reference Chart ▾
AlphaUS FittedCentimetresInches

Measurements are head circumference taken at the widest point above the ears.
Questions? Contact hello@topology.com

How to Use the Hat Size Converter

To find your perfect fit for professional cap production, follow these three simple steps:

  1. Measure: Wrap a flexible tape measure around the widest part of your head (about 1/8" above your ears).
  2. Input: Select your preferred unit (CM or Inches) and enter your measurement into the calculator above.
  3. Analyze: The tool will instantly generate your US Fitted Size, Alpha Size (S–XL), and the exact metric equivalent.

Why Accuracy Matters in Apparel Manufacturing

In the world of headwear manufacturing, even a 0.5cm discrepancy can lead to high return rates. This converter is designed based on standard industry grade rules to ensure your Tech Packs are accurate from the first prototype.

  • Fitted Hats: Require precise numerical sizing (e.g., 7 1/4).
  • Adjustable Caps: Use Alpha sizing (S/M/L) but still rely on base circumference.
  • Pro Tip: Always account for potential fabric shrinkage depending on your material choice.
Want a deep dive into hat sizing? Read our full guide on The Science of Hat Sizing: US vs. EU Standards to learn about measuring techniques and production grade rules.

Want to understand the science behind these measurements? Read our in-depth guide: The Science of Hat Sizing →