The really short answer: ask your shoemaker (or whichever merchant you are purchasing shoe products from).
Depending on your shoemaker, your shoe size may convert differently between the different sizing systems. Apart from that, the cutting and width of each shoe will ultimately affect which size you wear for that particular model. This is why it is safer to shop online for shoes and shoe care products from established stores that provide their own measuring and sizing charts, instead of attempting to convert or re-use the size from your existing shoes.
To understand why it is a bad idea to re-use your current shoe size from another shoemaker, or to convert sizes between different measuring systems, we’ll have to delve a little into how shoes are made, and how each system is denominated.
1. Different shoes, different widths
Traditionally, the size of a shoe is tied to the length rather than width of the shoe. The numerical quantity in each of the US, UK and EU measurement systems all refer to the length of the shoe relative to another. As such, we’d expect a US10 shoe to be as long as a US10 shoe from another shoemaker (they aren’t always, but we’ll discuss it later).
The problem arises when different shoe cuts have different widths, which is determined by shoe design rather than tied to the measure – even though the length of your feet should fit into US10 shoes, you might have to size up to longer US11 shoes for narrow cuts in order to accommodate the width of your feet.
Without knowing the shape of the last that the shoe was built on, simply reusing your current shoe size when purchasing from another shoemaker is as good as taking a potshot in the dark.
2. The US and UK measurement systems are not intuitive
US and UK shoe sizes are measured in “barleycorns”, which are roughly 1/3″ in length. However, the US starts counting from 1, so US sizes are 1 unit larger than their UK equivalents. That is to say, a US10 is the same length as a UK9, which are both 1/3″ longer than a US9 and UK8.
To further complicate size selection, US1 (UK0) shoes aren’t infinitely short – they are actually 12″ in length. As such, you cannot simply buy a US11 shoe if a visual test shows that your feet are 10% longer than a US10.
3. Converting from US/UK to EU takes complex arithmetic
Remember when I said that US1/UK0 isn’t actually 0cm in length? Well, an EU0 is. That means that in order to convert from US to EU, you’ll have to:
- subtract 1 from the numerical value of the US size
- multiply the result by 1/3″
- add 12″ to the result
- convert the whole thing into centimeters, because the EU system is based in centimeters
- divide the result by the length of an EU step
The difference between each EU size is called a “Paris point”, which is 2/3cm long.
You might be tempted to simply measure the length of your feet and convert that into an equivalent number of Paris points to find your EU size.
That’s not going to work too.
The EU length applies to a shoe fitting in the French way, where the toe is right up against the end and is extremely uncomfortable. You’ll have to add 1-2cm of air for a comfortable fit, and this is once again at the discretion of your shoemaker and his shoe cut.
4. Some shoemakers ignore even length conventions
Perhaps in a bid to retain their customer base, some shoemakers even disregard the purpose of having common measuring systems. One example would be Red Wings, whose boots are usually 1 size larger than their stated size.
Should I still purchase shoes and shoe trees online?
Seeing that there is no easy industry standard when it comes to shoe sizing, you might wonder if purchasing size-specific shoes and shoe trees online is worth the risk at all. However, we should not let the limitations of systems from a bygone era prevent us from enjoying the better time and cost efficiency that comes with online shopping. Reputable online stores already have solutions to work around these problems. When shopping online, you should:
1. Purchase from a store that provides their own measuring guide
Established online shoe and shoe care shops invest in collecting extensive data to create size guides that are uniquely tailored to their products. To help you find the best size for our ShoeTree Project shoe trees, we have created our very own printable sizing guide that measures your feet to find shoe trees of the same size.
2. Look out for exchange policies
More importantly, purchase from reputable online stores that allow you to exchange your product for the correct size in case your measurement goes wrong. This is the only surefire way that you do not end up stuck with a wrong size. At ShoeTree Project, we provide all domestic customers with a doorstep exchange if the size purchased is wrong.