Birkenstock Boston

For about 3 in 10 feet. If you follow Birkenstock's size guidance online, the Boston fits true to size for 31% of feet. Here, true to size means the size Birkenstock's guidance gives you is less than a full size away from the size that fits best, with enough toe room and enough forefoot volume.

Birkenstock did a very good job on width. Birkenstock's fit guide lists a foot length range and a foot width range for the narrow and the regular width at every size, so online shoppers can measure their feet at home and pick a width, not just a size. The guidance falls short on length: in our fittings, most of the misses came from too little room in front of the toes, not from the width.

Here is where every foot landed in the Boston when we followed Birkenstock's size chart and width chart.

Share of 16,802 feet. Each foot is counted once.

• Right size from the size chart: 31% of feet got a size and a width that fit both their foot length and their forefoot volume. Birkenstock's size guidance, including its width chart, worked well for this group in the Boston.
• Sized up for more forefoot volume: For 9% of feet, even the regular width had too little forefoot volume at the size the chart gave. The regular width is the Boston's widest, so going up a size was the only way to get more forefoot volume, and the bigger size also adds length in front of the toes.
• Sized up for toe room only: 36% of feet fit the forefoot volume once they had the right width, but the length the chart gave left their toes very little room. The Boston comes in whole sizes only, so if your foot is near the long end of a size's range on Birkenstock's chart, consider the next size up.
• Sized down for less forefoot volume: For 24% of feet, even the narrow width had too much forefoot volume at the size the chart gave. A smaller size was the only way to get less forefoot volume, with less room in front of the toes.

We measured the Boston in the regular width and virtually fitted 16,802 real feet from our earlier in-store 3D foot scanners. Out of 17,311 foot scans, those 16,802 feet fall in the size range of the Boston (EU 35 to 46). For every foot, we followed Birkenstock's size guidance online: the length chart, plus the width chart. We estimated the narrow width from standard width steps, not measured on the narrow version itself. A difference of a full size or more between Birkenstock's size and the size that fits best counts as a miss. These numbers show how the Boston fits a large group of feet, not how the shoe feels on your feet.