How Hat Sizing Works: A Smart Guide for Perfectly Fitting Headwear

When it comes to hats, fit matters—a lot. Whether you’re ordering custom caps for a team, launching branded merch, or simply shopping for yourself, understanding how hat sizing works can make the difference between a hat that gets worn daily and one that ends up in a drawer.

In this guide, we’ll break down how hat sizing works, where it comes from, and how to confidently choose the right fit—especially when dealing with fitted, adjustable, or one-size styles.

The Basics: What Is a Hat Size?

At its core, hat size is just a measurement of your head’s circumference—usually taken in inches or centimeters around the widest part of your head, just above the ears and eyebrows.

But instead of listing exact inches on the tag, most hatmakers use a sizing scale. That’s why you’ll see sizes like 7 1/4 or Large instead of just "22 inches."

There are three common sizing systems used today:

1. Numeric sizing (e.g. 7 1/8, 7 1/4) – Most common in fitted hats.
2. Letter sizing (S, M, L, XL) – Common in adjustable and stretch-fit styles.
3. One size fits most – Found in beanies, toques, and casual caps with stretch or adjustable straps.

 How Numeric Hat Sizing Works

Traditional hat sizing is based on the head’s circumference in inches, divided by pi (3.14). Hatters in the 1800s developed this method when constructing circular crowns by hand. While manufacturing has changed, the sizing stuck around.

Here’s a quick example:

• A 22.5” head circumference roughly translates to size 7 1/8.

Here’s a simple chart to help:

Letter Sizing: Small, Medium, Large & Beyond

When numeric sizes feel too detailed or you're ordering in bulk, many suppliers offer hats in generalized letter sizes:

• Small: Fits heads around 6 3/4 – 7
• Medium: Fits 7 1/8 – 7 1/4
• Large: Fits 7 3/8 – 7 1/2
• Extra Large: 7 5/8 and up

These ranges vary slightly by brand, so always check with your supplier. For branded apparel companies, selecting a size spread based on your audience (e.g., more mediums for general staff or more XLs for sports teams) helps avoid issues down the road.

 What About “One Size Fits Most”?

You’ll often see casual hats, toques, and beanies labeled as “one size fits most.” These rely on:

• Elastic materials that stretch to fit most head sizes.
• Adjustable features, like snapbacks, hook-and-loop (Velcro), or strapbacks.

This sizing is great for giveaways, promotional items, or events where fit flexibility is more important than precision.

⚠️ However, “one size fits most” isn’t always one size fits everyone. If you're ordering for a very specific group (e.g., kids, people wearing helmets, or clients with larger heads), it's worth checking size ranges or ordering samples first.

Why It All Matters for Custom Hats

Understanding hat sizing isn’t just for hat makers—it’s a strategic advantage for anyone ordering branded apparel.

• Ensures comfort for your team or audience
• Elevates your brand’s professionalism through better fit and presentation
• Reduces waste from unused or ill-fitting inventory
• Improves satisfaction when recipients get a hat they actually want to wear

In short: the right size turns a branded hat into a wearable, walkable billboard for your brand.

Final Tips Before You Order

• Always measure first: Use a soft tape and measure around the widest part of the head.
• Choose sizing formats based on the hat style: Fitted? Go numeric. Casual cap? Letter size or adjustable.
• Order a size range or sample set when in doubt.
• Ask your supplier for a sizing guide based on their specific styles.

Hat sizing may seem like a small detail—but in the world of branded merchandise, small details are what make your brand stand out.

Want help choosing the right hat style and size range for your next campaign or team order? We’re happy to help—from fit to finish. Reach out to our Customer Experience Team .