If you wanted to pick two mainstream brands that size as differently as possible, Zara and Old Navy would be a strong pair. Zara cuts slim on European blocks, labels in EU numbers, and runs small — worst in fitted pieces, jeans, and its TRF line. Old Navy is famous for the opposite: generous sizing, with finished garments that often measure a size or more over the label.
The two also speak different sizing languages — EU numeric at Zara, US alpha at Old Navy — so the tables below align rows by body measurement rather than by letter. Even before the fit reputations kick in, the charts alone put the same letter on noticeably different bodies.
The short answer
Zara runs much smaller — expect to drop a size, often two, going from Zara to Old Navy
Start with the charts: a Zara M fits a 90 cm (35.4") bust, which falls between Old Navy's S (34–35") and M (36–37"); a Zara men's L (99–103 cm chest) matches an Old Navy M (39–41"). That's roughly a half-to-one letter gap on paper, with Old Navy's letters covering the larger bodies.
Then add the fit reputations, which pull in opposite directions. Zara garments run small against their own chart — one size up is the standard advice for anything fitted. Old Navy garments run large against theirs — independent tests have found pants measuring inches over the label, and sizing down one is the standard advice for a fitted look. Stack the chart gap and the fit gap and a Zara L shopper can land in an Old Navy S–M.
Zara vs Old Navy at a glance
| Zara | Old Navy | |
|---|---|---|
| Sizing system | EU numeric (34–44) with letters; a 38 is a US 6 | US alpha (XS–XXL) over US numeric sizes |
| Overall fit | Runs small — fitted pieces, jeans, and TRF worst | Runs large — garments often measure a size or more over the label |
| Standard advice | Size up in anything fitted | Size down for a fitted look, especially tops, dresses, jeans |
| Denim | Runs small; one size up is the norm | Runs big in waist and hip; stretch relaxes further with wear |
| Where labels are reliable | Zara Woman line runs closest to true to size | Basics — plain tees, sweats, activewear — stay near true to size |
Women's size mapping by bust
Rows are aligned by body bust measurement, not by label — Zara sizes in EU numbers, Old Navy in US alpha sizes. Zara figures are as commonly republished from its per-product size tool; Old Navy figures are from its published chart.
| Zara size | Zara bust | Closest Old Navy size | Old Navy bust |
|---|---|---|---|
| XS (EU 34) | 82 cm · 32.3" | XS | 31–33" · 78.5–84 cm |
| S (EU 36) | 86 cm · 33.9" | XS–S | 34–35" · 86.5–89 cm |
| M (EU 38) | 90 cm · 35.4" | S–M | 36–37" · 91.5–94 cm |
| L (EU 40) | 94–96 cm · 37–37.8" | M–L | 38.5–40.5" · 98–103 cm |
| XL (EU 42) | 98–102 cm · 38.6–40.2" | L | 38.5–40.5" · 98–103 cm |
| XXL (EU 44) | 102–108 cm · 40.2–42.5" | L–XL | 42.5–45" · 108–114.5 cm |
Women's waists at the matched sizes
Body waist measurements for the bust-matched pairs above. Remember Old Navy garments tend to measure over these chart figures, so in practice the gap is wider than the table shows.
| Zara size · waist | Old Navy size · waist |
|---|---|
| XS · 62–64 cm · 24.5–25" | XS · 23–25" · 58.5–63.5 cm |
| S · 66 cm · 26" | XS–S · 26–27" · 66–68.5 cm |
| M · 70 cm · 27.6" | S–M · 26–29" · 66–73.5 cm |
| L · 74–76 cm · 29.1–30" | M–L · 28–32.5" · 71–82.5 cm |
| XL · 78–82 cm · 30.7–32.3" | L · 30.5–32.5" · 77.5–82.5 cm |
| XXL · 82–88 cm · 32.3–34.6" | L–XL · 34.5–37" · 87.5–94 cm |
Men's tops by chest
Body chest measurements, aligned by measurement rather than letter. Zara figures are as commonly republished from its size guidance. Old Navy's men's chart starts at S.
| Zara size · chest | Closest Old Navy size · chest |
|---|---|
| M · 94–98 cm · 37–38.5" | S · 37–38" · 94–96.5 cm |
| L · 99–103 cm · 39–40.5" | M · 39–41" · 99–104 cm |
| XL · 104–108 cm · 41–42.5" | M–L · 39–45" · 99–114.5 cm |
| XXL · 109–114 cm · 43–45" | L · 43–45" · 109–114.5 cm |
Switching between Zara and Old Navy
- Going Zara → Old Navy: drop one letter as your baseline, and consider two for fitted tops, dresses, and jeans — Old Navy garments often measure over their own chart.
- Going Old Navy → Zara: go up at least one letter, and another for Zara jeans, blazers, structured dresses, or anything TRF.
- Old Navy basics (plain tees, sweats) are the exception — they run close to true to size, so a one-letter shift from Zara is usually enough there.
- In denim the brands need opposite corrections: size up at Zara, size down at Old Navy — especially in stretchy washes, which relax further with wear.
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 Zara size guide and the Old Navy size guide.
Zara vs Old Navy sizing FAQs
Which runs smaller, Zara or Old Navy?
Zara, and it isn't close. The charts already put the same letter on a smaller body at Zara — a Zara men's L matches an Old Navy M — and the fit reputations widen the gap: Zara garments run small against their chart while Old Navy garments often measure a size or more over theirs.
What Old Navy size should I buy if I wear a Zara large?
Usually a medium, sometimes a small in fitted styles. A Zara L fits a 94–96 cm (37–37.8") bust, which sits between Old Navy's M and L on the chart — and because Old Navy cuts generous, the M is the safer starting point for anything fitted.
Do I size up or down in jeans at these brands?
Opposite directions. Zara jeans run small — one size up is the standard advice. Old Navy jeans run big in the waist and hip, and most washes stretch further with wear, so take the smaller size when you're between sizes there.
Are Old Navy and Zara sizes consistent between items?
Neither brand is a model of consistency, but the failure modes differ. Zara varies by line — TRF runs slimmest, Zara Woman more generous — and offers a per-product size calculator for that reason. Old Navy splits by category: basics run close to true to size while fashion pieces carry the generous sizing.
Is a Zara medium the same as an Old Navy medium?
No. A Zara women's M fits a 90 cm (35.4") bust while Old Navy's M covers 36–37" (91.5–94 cm) — and the actual Old Navy garment usually measures bigger still. Most Zara M shoppers fit an Old Navy S in fitted styles.
