Gap vs Old Navy Sizing: How Do They Compare? (Same Parent Company, Different Fits)

Same Company, Different Fits

Gap and Old Navy are both owned by Gap Inc. (along with Banana Republic and Athleta), which leads many shoppers to assume that sizing is consistent across the brands. After all, they share supply chains, design teams, and corporate infrastructure. But if you've ever bought the same size in both stores and found that they fit differently, you're not imagining things.

Gap and Old Navy do not size identically, and understanding the differences can save you from frustrating fitting room experiences (or worse, online returns).

The Core Sizing Differences

Vanity Sizing at Old Navy

The most significant difference is that Old Navy sizes run approximately one size larger than Gap. This is a deliberate strategy called "vanity sizing" — the idea is that customers feel good about fitting into a smaller size number, which can drive purchases.

In practical terms:

• If you're a Medium at Gap, you might be a Small at Old Navy
• If you wear size 8 jeans at Gap, you might fit into a size 6 at Old Navy

This isn't universally true across every single garment, but it's a reliable general pattern that's been confirmed by independent testing and countless shopper reports.

Fabric Quality and Stretch

Beyond the size label differences, the fabrics used in each brand contribute to fit differences:

• Gap uses slightly heavier cotton, more structured fabrics, and less reliance on stretch blends in their core line. This means Gap garments tend to maintain their shape better over time but feel less forgiving initially.
• Old Navy frequently uses lightweight, stretchy fabrics that are more forgiving across a range of body types. Their jeans, for instance, often contain more elastane than Gap's equivalent, which means they stretch more throughout the day.

The result? Even when the flat measurements of a Gap and Old Navy garment are similar, the Old Navy piece may *feel* larger because of the additional stretch.

Cut and Proportions

The two brands target slightly different demographics:

• Gap aims at a slightly more fashion-forward, "classic with a twist" customer. Their cuts tend to be a bit more tailored — narrower shoulders on men's shirts, higher rises on women's jeans.
• Old Navy targets a broader, more value-conscious market. Their cuts tend to be more generous and accommodating — wider through the body, more relaxed through the arms and legs.

Category-by-Category Breakdown

Women's Tops

Recommendation: If you're a Gap Medium, try Old Navy Small first. For loose/oversized styles, you may need to go down two sizes at Old Navy.

Women's Jeans

This is where the difference is most noticeable. Gap's women's jeans have a more tailored fit, especially in the "True Skinny" and "High Rise" lines. Old Navy's Rockstar jeans (their bestselling women's jean) are noticeably more generous through the hip and thigh.

Key difference: Gap uses its in-house sizing scale. Old Navy's jeans have approximately 1" more room in the waist and 1-2" more room in the hips for the same size number.

Men's Shirts

Men's sizing between the two brands is more consistent than women's, but differences still exist. Gap's men's shirts tend to be slimmer in the body and slightly longer than Old Navy's, which are cut wider and slightly shorter.

For button-down shirts: a Gap Medium typically fits a 38-40" chest, while an Old Navy Medium accommodates a 40-42" chest.

Kids' Clothing

Perhaps surprisingly, kids' sizing is the most consistent between Gap and Old Navy. Both brands use the same general size chart for children, though Old Navy's kids' clothes tend to use slightly softer, stretchier fabrics that can feel a bit roomier.

How to Shop Smartly Across Both Brands

1. Don't assume your Gap size equals your Old Navy size. Start by trying one size down at Old Navy compared to your Gap size.

1. Use flat measurements when shopping online. Both Gap and Old Navy provide garment measurements on many of their product pages. Compare the actual measurements rather than the size labels.

1. Take advantage of shared return policies. While you can't return Gap clothes at Old Navy or vice versa, both brands have generous online return windows (typically 30-45 days). Use this to your advantage when trying a new size.

1. Read reviews filtered by body type. Both websites allow you to filter reviews, and many reviewers mention their height, weight, and whether the item runs true to size.

1. Consider the fabric composition. Check the material tag. An Old Navy shirt in 100% cotton will fit differently than one in a cotton-modal blend, even if they're the same labeled size.

For detailed size charts of both brands, visit our Gap Size Chart and Old Navy Size Chart pages. To convert between the two brands directly, try our Size Converter.