Birkenstock Shoe Sizing Guide: Do They Run Small?
Birkenstock sizes run large — the cork footbed is contoured and anatomical rather than flat, so it effectively adds volume and length. Most buyers find they need to go a full size down from their US shoe size, or use the EU size printed on the footbed as the reference. The more important choice with Birkenstock is footbed width: narrow (B) or regular (D).
Across our data Birkenstock runs large: 5% of wearers report it runs small, 35% true to size and 60% large.
Birkenstock sizing philosophy
Birkenstock has been making contoured cork footbeds since 1774. The sizing logic is different from any other shoe: what matters first is the footbed width — narrow or regular — which determines whether the anatomical arch contour sits under your arch rather than under your midfoot. Get the width right first; the length second. The brand recommends measuring your foot on the Birkenstock size chart rather than converting from another brand's number.
The cork footbed compresses and molds to your foot over the first 10–20 wearings — the famous Birkenstock "break-in." A new pair feels firm and the arch bump feels prominent; a broken-in pair feels custom. During break-in, the footbed effectively gets a fraction shorter as it compresses, so checking slightly long rather than slightly short is the safer call.
How Birkenstock models differ
There is no single "Birkenstock size" — different lines are graded on different lasts. Here is how the key models compare:
- Arizona (two-strap sandal)
- The most forgiving Birkenstock for first-time buyers: two adjustable straps allow for a range of fits. The reference model for finding your Birkenstock size.
- Boston (closed-toe clog)
- Runs roomy with extra length at the toe. Many buyers find their usual Birkenstock size — one full US size down — is correct, or even half a size below that.
- Gizeh (toe-post sandal)
- Same footbed as the Arizona but a toe post instead of straps. True to your Birkenstock size; the narrow (B) width matters here since the strapping is minimal.
Practical sizing advice
If you normally wear US 9, start by checking Birkenstock in EU 40 (the brand's own chart is the most reliable reference). Check narrow vs regular footbed width before checking the length.
If your feet are wide
Birkenstock's width system is footbed-width, not upper width: regular (D/E) is for standard to wide feet, narrow (B) is for narrow feet. Wide-footed buyers should choose regular and confirm the arch contour sits correctly. The brand's footbed is inherently accommodating of forefoot spread in a way that a closed upper shoe is not.
If you wear US 9, start by checking Birkenstock in US 8.5
This table starts from the US size you wear in a true-to-size brand, converts it to a foot length, and applies Birkenstock's measured fit so you can see the first size to check — plus the UK, EU and CM equivalents.
| You normally wear (US) | Foot length | Check Birkenstock (US) | UK | EU | CM |
|---|---|---|---|---|---|
| US 7 | 246mm | US 6.5 | 6 | 37 | 24.5 |
| US 8 | 254mm | US 7.5 | 7 | 38 | 25.5 |
| US 9 | 262mm | US 8.5 | 8 | 39 | 26 |
| US 10 | 271mm | US 9.5 | 9 | 41 | 27 |
| US 11 | 279mm | US 10.5 | 10 | 42 | 28 |
| US 12 | 288mm | US 11.5 | 11 | 43 | 29 |
EU sizes are always rounded to a whole size — there is no exact half-size equivalent. The recommended Birkenstock size applies this brand's average fit; individual models still vary, so check the model notes above.
Full Birkenstock size conversion
For the complete Birkenstock size chart with US, UK, EU and CM by foot length, the reported-fit distribution and our sources, visit the Birkenstock brand hub.