In-depth – Why pressure determines how much leather shoes stretch

That leather shoes can stretch is something most people are aware of, but how much they actually do so is far less straightforward. A key reason for this is that leather doesn’t stretch according to any fixed rule, but instead adapts to the forces it’s exposed to. In practice, this means that pressure from the foot is one of the most decisive factors in how a shoe will change over time.

This is a topic that I’ve been sort of writing about before, a decade ago or so on the Swedish version of the blog, later published in English headlined what affects how leather shoes are stretched here and here. Now focus is solely on the fact that the tighter the shoes are, the more they stretch, put shortly. Something many have misconceptions about.

If we take two people wearing the exact same model in the same size, the difference can be quite striking. For one person the shoe may feel snug over the ball of the foot or across the instep, creating constant pressure on the upper. After a number of wears, that pressure causes the leather to give, and the fit becomes noticeably more accommodating. For the other person, whose foot doesn’t press in the same way, the shoe might feel comfortable from the start and then remain largely unchanged, just conformed to the foot better. The leather simply hasn’t been forced to stretch. In this sense, leather stretches as much as required, but rarely more. If the second person would try the first person’s shoes after they’ve been broken in, they would feel much larger, despite being more or lesst identical in fit from the start.

This also explains why stretching is highly localised. The vast majority of change tends to happen over the widest part of the foot, where pressure is greatest during both standing and walking. Even within a single pair, the result can therefore be uneven, with certain parts giving significantly while others remain almost exactly as they were.

It’s also the reason why general statements about how much shoes stretch tend to be misleading. Even if all other variables are identical, the outcome can differ greatly depending on the wearer. While factors like leather type, construction method, backings, how tightly the shoe was lasted etc all influence the potential for stretch, they don’t in themselves determine the result. Without sufficient pressure, even soft and flexible leather will change very little.

So don’t listen to sales people or others who state that “they will stretch about half a size, so they should feel a bit snug at first”. I always try to explain that when you try on a pair of shoes in store or at home after being ordered from an online store, they should feel as good as possible. When you have them on your feet for a few minutes and just take a few steps around, it’s something very different from when they are used for a full day during a lot of walking. Then small fit things can be expected to give when you are wearing them in, or be taken care of in advance by stretching or if they are small with various inserts etc.

Understanding the above makes it easier to approach fit in a more realistic way. Above all, it highlights that stretching is not something that happens automatically, but something that occurs in response to how the shoe is actually put under pressure. But the fact that leather always conform to the foot, and can stretch if needed to, is part of what makes it such a great and comfortable material for footwear.