On paper, Uniqlo and GAP speak the same language: both label clothes XS through XXL, and both map those letters to almost identical US numeric sizes — S is 4–6, M is 8–10, L is 12–14 at either store. That's exactly what makes the pair treacherous. The labels match; the clothes don't.
Uniqlo builds on Japanese fit blocks — trim chest and shoulders, narrow sleeves, slightly short torso — while GAP is the reference point for roomy, classic American fit. Stack the charts and GAP's measurements sit about an inch bigger at the same letter, before you even account for GAP's generous ease. Here are both charts side by side and the one-size rule that makes switching painless.
The short answer
Uniqlo runs smaller — most GAP shoppers go up one size at Uniqlo
Uniqlo runs small and GAP runs true to size by US standards, leaning slightly generous — so the gap between them is real even though the size labels look interchangeable. At the same letter, GAP's women's chart runs roughly an inch bigger in the bust (Uniqlo S covers a 33–34" bust; GAP S covers 34.5–35.5"), and GAP's cut adds ease on top of that. Most people who wear a medium at GAP take a large at Uniqlo.
The compensation: Uniqlo is far more consistent. Its fit blocks barely change between seasons, so your Uniqlo size holds once you find it, while GAP's fit drifts between items and seasons — its relaxed and oversized lines run notably big, and pant lengths skew odd. Coming from GAP, size up once at Uniqlo and you're mostly done; going the other way, read GAP's fit description (slim, straight, relaxed) before you trust your size.
Uniqlo vs GAP at a glance
| Uniqlo | GAP | |
|---|---|---|
| Overall fit | Runs small — slim Japanese fit blocks, short sleeves and torso | True to size, leaning slightly generous — classic American ease |
| Size labels | Alpha sizes; S = US 4–6, M = US 8–10 | Same alpha-to-numeric mapping — but on a bigger body chart |
| Where to adjust | Size up one from your GAP size; two in slim-fit lines | Size down in relaxed and oversized styles |
| Consistency | Very consistent — fit blocks barely change between seasons | Fit drifts between items and seasons more than between sizes |
| Lengths | Sleeves and torsos run short — tall shoppers should check lengths | Pant lengths skew odd: regular often short, long very long |
US numeric sizes behind each letter (women)
Both brands publish US numeric equivalents for their letters — and they nearly match. The mismatch is in the body measurements behind them, shown in the next table.
| Size | Uniqlo US size | GAP US size |
|---|---|---|
| XS | 0–2 | 0–2 |
| S | 4–6 | 4–6 |
| M | 8–10 | 8–10 |
| L | 12–14 | 12–14 |
| XL | 16–18 | 16–18 |
| 2XL / XXL | 20–22 | 20 |
Women's body measurements side by side
Body measurements from each brand's published chart, compared at the same letter. GAP's chart runs roughly an inch bigger at every size.
| Size | Uniqlo bust | GAP bust | Uniqlo waist | GAP waist |
|---|---|---|---|---|
| XS | 31–32" · 78–83 cm | 32.5–33.5" · 82.5–85 cm | 24–25" · 60–65 cm | 25.5" · 65 cm |
| S | 33–34" · 83–88 cm | 34.5–35.5" · 87.5–90 cm | 26–27" · 65–70 cm | 26.5–27.5" · 67.5–70 cm |
| M | 35–37" · 88–94 cm | 36.5–37.5" · 92.5–95.5 cm | 28–30" · 70–76 cm | 28.5–29.5" · 72.5–75 cm |
| L | 37–40" · 94–101 cm | 39–40.5" · 99–103 cm | 30–33" · 76–83 cm | 30.75–32" · 78–81.5 cm |
| XL | 40–43" · 101–109 cm | 42–44" · 106.5–112 cm | 33–36" · 83–91 cm | 33.75–35.75" · 85.5–91 cm |
Men's tops side by side
Body chest measurements at the same letter. Uniqlo's bands start lower at every size — its M begins at a 38" chest where GAP's begins at 39" — and Uniqlo's cut is trimmer on top of the chart difference.
| Size | Uniqlo chest | GAP chest |
|---|---|---|
| XS | 32–35" · 81.5–89 cm | 34–36" · 86.5–91.5 cm |
| S | 35–38" · 89–96.5 cm | 36–38" · 91.5–96.5 cm |
| M | 38–41" · 96.5–104 cm | 39–41" · 99–104 cm |
| L | 41–44" · 104–112 cm | 42–44" · 106.5–112 cm |
| XL | 44–47" · 112–119.5 cm | 45–47" · 114.5–119.5 cm |
| XXL | 47–50" · 119.5–127 cm | 48–50" · 122–127 cm |
Switching between Uniqlo and GAP
- Going GAP → Uniqlo: take one size up as your default, and two in anything Uniqlo labels slim fit.
- Going Uniqlo → GAP: your Uniqlo size minus one usually works — but size down again in GAP's relaxed and oversized styles.
- Don't trust the matching letters or US numbers; compare the bust, waist, or chest measurement on each chart instead.
- Watch lengths in both directions: Uniqlo sleeves and torsos run short for tall shoppers, while GAP's regular pant inseam often runs short and its long runs very long.
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 Uniqlo size guide and the GAP size guide.
Uniqlo vs GAP sizing FAQs
Which runs smaller, Uniqlo or GAP?
Uniqlo, clearly. It cuts on Japanese fit standards — slimmer through the chest, shoulders, and sleeves — while GAP uses a roomy classic American fit. At the same letter, GAP's chart also measures about an inch bigger, so most GAP shoppers go up one size at Uniqlo.
I wear a medium at GAP — what size am I at Uniqlo?
Most people who wear a medium at GAP take a large at Uniqlo. Uniqlo's medium fits roughly like a US small-to-medium, with a trimmer cut through the body and shorter sleeves. In Uniqlo's slim-fit lines, consider going up two from your GAP size.
Do Uniqlo and GAP use the same size labels?
Almost — both run XS through XXL and map the letters to nearly identical US numeric sizes (S is 4–6, M is 8–10 at both). But the body measurements behind the letters differ by about an inch, and the cuts differ more, so the matching labels are misleading.
Which brand is more consistent between items?
Uniqlo. Its fit blocks change little between seasons, so your size in a category tends to hold. GAP's bigger issue is drift — fit varies more between GAP items than between sizes, and relaxed or oversized pieces run notably big. At GAP, read the fit description before the size chart.
Is the men's sizing gap as big as the women's?
It's smaller on the chart — Uniqlo's and GAP's men's chest bands overlap heavily at M and L — but Uniqlo's bands start lower at every size and the cut is trimmer. Men used to GAP's fit usually still prefer one size up at Uniqlo, especially in slim-fit shirts and outerwear.
