What Do S, M, L, XL Mean? Clothing Size Letters Explained

S, M, L, XL — these letters appear on every clothing label, but what do they actually mean? And why does a size M in one brand fit completely differently in another?

The Standard Sizing System

S, M, L, XL (Small, Medium, Large, Extra Large) is the most common clothing sizing system worldwide. It's known as "alpha sizing" because it uses letters instead of numbers.

Men's Standard Sizing (approximate chest measurements)

Women's Standard Sizing (approximate bust measurements)

Why Sizing Varies Between Brands

The biggest frustration with letter sizing is inconsistency. Here's why brands differ:

Vanity sizing Some brands label larger garments with smaller sizes to make customers feel better

Target audience A brand targeting athletes (Nike, Adidas) may have different proportions than a fashion brand (Hugo Boss)

Regional standards US, EU, and Asian sizing all use different baseline measurements

Garment type Casual wear, formal wear, and activewear have different fit philosophies

How to Find Your Correct Size

The most reliable method is to:

1. Measure your body accurately

2. Compare your measurements to the specific brand's size chart

3. Consider the garment's fit description (slim, regular, relaxed)

Use our body measurement tool to get accurate measurements from a photo, then check our brand size charts for Nike, Adidas, Uniqlo, and more.

The Takeaway

Don't buy based on the letter alone. A size M in one brand could be a size S or L in another. Always check the brand's specific size chart and your own measurements before purchasing.