There are questions that you ask me very often and that I never know how to answer: “small size?”, “large size?”, “my little one always wears a 25 and in this brand he wears a 22”.
Why don't I know how to answer them? I really don't know what you're comparing them to.
In the chart you can see the size 28 of several brands that we have in store. The green dotted line would be the average. Everything above would be “large” and everything below would be “small”. But it is not that simple. 
Why? Because, again, I don't know what you're comparing. I don't know if you're comparing Beda vs Pegres or Protetika vs Mukishoes. Sometimes you tell me that the little one is wearing brands that we haven't touched since 2018 because we're still waiting in the virtual queue 😅 And sometimes it turns out that the little ones are wearing traditional shoes...
I will always ask you to measure your feet and look at the size guides. The reason is that to make it more complicated, even within the same brand there can be size variations 🤯
We have created the graph based on the average lengths of each brand. Although the lasts are exactly the same and measure the same, the materials and the pattern can cause the measurements to vary. For example, a canvas boot that can have at most one layer of fabric and a lining is not the same as a winter boot that has leather, insulating material and a sheepskin lining. The more layers, the less space.
And all this, speaking only of the length… Now imagine including the triple somersault: width, instep and foot shape.
In my case, there are shoes that seem to me to be “small” because I have a Greek foot and my long toe rubs against the end because they are anatomically shaped. Then there are shoes that measure exactly the same, but I think they are “large” because having a square toe my long toe fits better and with plenty of room to spare.
Moral : always, always take measurements and look at the size guide.
Follow me for more tips @caclesbarefoot 🤓