GAP and Old Navy are sister brands under Gap Inc., both sized in US numeric and alpha sizes, and their published charts look reassuringly similar on paper. That similarity is exactly what trips people up: the charts may rhyme, but the garments don't. GAP runs true to size with a slightly generous classic American cut, while Old Navy is one of the most consistently generous-sizing mainstream brands going.
Old Navy's reputation isn't about its chart — it's about the garments, which frequently measure larger than the chart suggests, especially in women's tops, dresses, and jeans. Independent tests have found pants measuring inches over the marked size. Below are both brands' charts side by side, plus the practical size adjustments for moving between the two.
The short answer
Old Navy runs bigger — same family, same-looking charts, noticeably roomier garments
By the published numbers the two brands are close — Old Navy's chart even reads marginally smaller in a few spots — but the fit verdicts diverge: GAP is true to size leaning slightly generous, while Old Navy runs large, with finished garments often measuring a size or more over the label. That's why the standard advice for anything fitted at Old Navy is to size down one from your GAP size.
The exception is basics: Old Navy's plain tees, sweats, and activewear stay closer to true to size, so your GAP size carries over there. The generosity is concentrated in fashion pieces — fitted tops, dresses, and denim — and both brands share the family trait that relaxed and oversized lines run big enough to warrant sizing down regardless.
GAP vs Old Navy at a glance
| GAP | Old Navy | |
|---|---|---|
| Fit verdict | True to size, leaning slightly generous | Runs large — garments often measure a size or more over the label |
| Place in the Gap Inc. family | The middle of the trio — roomier than Banana Republic | The most generous cut of the three sister brands |
| Where to size down | Relaxed and oversized styles only | Fitted tops, dresses, and jeans — basics stay true to size |
| Denim | Mostly true in the waist; very stretchy washes relax — consider down | Runs big in waist and hip; take the smaller size when in doubt |
| Consistency | Fit drifts between items and seasons | Generosity is predictable: fashion pieces big, basics closer to true |
Women's bust and waist side by side
Body measurements from each brand's published chart, by shared alpha label. The charts are close — the fit difference shows up in the garments, which run roomier at Old Navy for the same label.
| Size | GAP bust | Old Navy bust | GAP waist | Old Navy waist |
|---|---|---|---|---|
| XS | 32.5–33.5" · 82.5–85 cm | 31–33" · 78.5–84 cm | 25.5" · 65 cm | 23–25" · 58.5–63.5 cm |
| S | 34.5–35.5" · 87.5–90 cm | 34–35" · 86.5–89 cm | 26.5–27.5" · 67.5–70 cm | 26–27" · 66–68.5 cm |
| M | 36.5–37.5" · 92.5–95.5 cm | 36–37" · 91.5–94 cm | 28.5–29.5" · 72.5–75 cm | 28–29" · 71–73.5 cm |
| L | 39–40.5" · 99–103 cm | 38.5–40.5" · 98–103 cm | 30.75–32" · 78–81.5 cm | 30.5–32.5" · 77.5–82.5 cm |
| XL | 42–44" · 106.5–112 cm | 42.5–45" · 108–114.5 cm | 33.75–35.75" · 85.5–91 cm | 34.5–37" · 87.5–94 cm |
| XXL | 46–47.5" · 117–120.5 cm | 47.5" · 120.5 cm | 37.75" · 96 cm | 39.5" · 100.5 cm |
Women's hips side by side
Body hip measurements from each brand's published chart. From L upward Old Navy's chart runs wider, on top of its roomier garments.
| Size | GAP hip | Old Navy hip |
|---|---|---|
| XS | 36.5" · 92.5 cm | 34–36" · 86.5–91.5 cm |
| S | 36.5–37.5" · 92.5–95.5 cm | 37–38" · 94–96.5 cm |
| M | 39.5–40.5" · 100.5–103 cm | 39–40" · 99–101.5 cm |
| L | 41.75–43" · 106–109 cm | 41.5–43.5" · 105.5–110.5 cm |
| XL | 44.75–46.75" · 113.5–118.5 cm | 45.5–48" · 115.5–122 cm |
| XXL | 48.75" · 124 cm | 50.5" · 128.5 cm |
Men's tops side by side
Body chest measurements. Old Navy publishes S–XL only; the M rows are identical, while Old Navy's L and XL chart larger chests than GAP's.
| Size | GAP chest | Old Navy chest |
|---|---|---|
| S | 36–38" · 91.5–96.5 cm | 37–38" · 94–96.5 cm |
| M | 39–41" · 99–104 cm | 39–41" · 99–104 cm |
| L | 42–44" · 106.5–112 cm | 43–45" · 109–114.5 cm |
| XL | 45–47" · 114.5–119.5 cm | 47–49" · 119.5–124.5 cm |
Switching between GAP and Old Navy
- For anything fitted at Old Navy — tops, dresses, jeans — start one size down from your GAP size.
- Keep your GAP size in Old Navy basics: plain tees, sweats, and activewear stay closer to true to size.
- Both brands size their relaxed and oversized lines genuinely big — size down in those whichever store you're in.
- In denim, the directions differ: GAP is mostly true in the waist (down only in very stretchy washes), while Old Navy jeans run big enough that the smaller size is the default when you're in between.
Measurements are based on each brand's published size charts and may vary by garment, fabric, and region. For the full charts and fit notes, see the GAP size guide and the Old Navy size guide.
GAP vs Old Navy sizing FAQs
Is Old Navy sizing the same as GAP?
The published charts are similar — they're sister brands — but the garments are not. Old Navy cuts noticeably roomier than GAP for the same label size. If you wear a medium at GAP, an Old Navy small will often fit the same way.
Should I take my GAP size at Old Navy?
In basics, yes — tees, sweats, and activewear run close to true to size. In fitted tops, dresses, and jeans, go one size down: Old Navy garments frequently measure a size or more over the label in those categories.
Why does Old Navy fit bigger if the charts look the same?
Because the chart lists body measurements, not garment measurements — and Old Navy's finished garments often measure larger than the chart suggests. Independent tests have found Old Navy pants measuring inches over the marked size, which is why the brand's fit verdict is "runs large" while GAP's is "true to size."
Do GAP and Old Navy jeans fit the same?
No. GAP jeans run mostly true to size in the waist, with stretchy washes relaxing over time. Old Navy jeans tend to run big in the waist and hip on top of having stretch, so most shoppers take the smaller size there — often one below their GAP denim size.
Which brand is more consistent?
Old Navy's pattern is at least predictable: fashion pieces run big, basics run true. GAP's bigger reported issue is drift — fit varying between items and seasons — so at GAP it pays to read the fit description (slim, straight, relaxed) before the size chart.
