Allbirds Size Guide: How to Get a Better Fit

Direct answer: start with the size guide on the exact Allbirds product page you want to buy. Current Allbirds pages say most whole-size shoes fit true to size for most customers, but if you have wide feet or fall between sizes, Allbirds suggests sizing up on whole-size styles. Some lines also run differently, so one old universal chart is not enough.

Table Of Contents

Start with the current brand rule

On Allbirds' current men's collection page, the brand says most whole-size shoes fit true to size for most customers and adds that if you have wide feet or are between sizes, you should size up for whole-size styles. The same page also says that half-size styles such as Tree Gliders and Tree Dasher 2 can usually be ordered in your normal size: Allbirds men's collection fit guidance.

Women's baseline chart from a current product page

If you want a simple starting point, the current Women's Tree Runner page lists the following US, UK, and cm conversions. Treat this as a product-page chart, not a promise for every Allbirds line.

US	UK	cm
5	2 - 2.5	22
6	3 - 3.5	23
7	4 - 4.5	24
8	5 - 5.5	25
9	6 - 6.5	26
10	7 - 7.5	27
11	8 - 8.5	28

Men's baseline chart from a current product page

The current Men's Tree Runner page shows this whole-size conversion as a quick baseline:

US	UK	cm
8	7	26
9	8	27
10	9	28
11	10	29
12	11	30
13	12	31
14	13	32

Fit changes by line, so read the shoe page

This is where old blanket advice breaks down. Current Allbirds pages show meaningful differences between lines:

Current style example	What Allbirds says	What to do with that
Women's Tree Runner	Tends to run small	Start one size up from your usual size
Men's Tree Runner NZ	Fits true to size for most customers	Start with your normal size
Women's Varsity Airy	Fits true to size and runs slightly long	Be cautious about sizing up unless you need width
Women's SuperLight Tree Runner	Fits true to size; wide feet or between sizes should size up	Size up only if you need extra room

What the current site says about width

Allbirds' current collection guidance says its shoes are not specifically categorized as wide or narrow, and instead describes the materials as accommodating a range of foot shapes: Allbirds fit FAQ. That matters because older internet charts often show exact width conversions that are not present on the current official pages.

How to use the cm row correctly

On current Allbirds product pages, the cm row is the most useful starting point when you already know your foot length. Compare your longer foot to the cm row on the exact shoe page you are buying, then check that page's fit note for whether the style runs small, true to size, or slightly long. That is more reliable than reusing a chart from a different Allbirds line.

Half sizes and unisex conversion

Current Allbirds pages show that not every line is whole-size only. For example, the Varsity Airy includes women's half sizes, and the Tree Runner NZ includes a unisex conversion note, saying that women's 11.5-12 can try men's 10.5-11, while men's 7-7.5 can try women's 8-8.5. Use those live product-page conversions when they are available instead of guessing.

Quick checklist before you order

Check the size guide on the exact shoe page, not a generic Allbirds chart.
Use the cm row first if you know your foot length.
Read the fit note for that model: runs small, true to size, or slightly long.
If the style is whole-size only and you are between sizes or have wide feet, current Allbirds guidance says size up.
If the style offers half sizes, use the live product-page conversion instead of rounding automatically.

Bottom line

The best current Allbirds size guide is not a single universal chart. It is the combination of the exact product-page conversion table and that model's fit note. Use the cm row as your starting point, then adjust only when the live Allbirds page says that specific line runs small, long, or roomier.