Why Shoe Size Conversion Is Not an Exact Science – Part 2

If shoe sizing were completely standardised, converting between US, UK and European sizes would be simple.

Unfortunately, it isn’t.

A US 9, UK 8 or EU 42 may look like an exact conversion on a size chart, but in real footwear production, the actual fit can still vary.

Different Sizing Systems Use Different Steps

Traditional UK sizing is based on the barleycorn system, where one full size is approximately 8.47 mm.

European sizing commonly uses the Paris Point system, where one size is approximately 6.67 mm.

This already tells us something important:

Different sizing systems do not increase in exactly the same way.

That is one reason why a conversion chart can only provide an approximate equivalent.

What Happens in Actual Shoe Production?

The situation becomes even more complicated in real factories.

From our experience working with footwear manufacturing for more than 20 years, shoes made for different markets are not always graded using exactly the same method.

For example, many shoes produced for the US market may be graded in increments closer to 6.67 mm, while traditional UK grading commonly uses approximately 8.47 mm.

This does not mean every US shoe follows one universal 6.67 mm standard.

It simply means that the grading method used in production can vary depending on the brand, factory, last and market specification.

Why Can the Same Brand Fit Differently?

This is another common question.

Customers often assume:

Same brand + same size = same fit.

But that is not always true.

Large footwear brands may produce different styles in different factories.

Some orders may also be managed through third-party buying agents or trading companies, rather than every style being produced under exactly the same factory and grading system.

Different styles can therefore use:

• different shoe lasts
• different toe shapes
• different widths
• different grading rules
• different materials and construction
• different fit allowances

So one style marked US 9 may not feel exactly the same as another US 9 from the same brand.

A Shoe Size Is a Reference, Not an Exact Measurement

This is probably the most useful point to remember.

A shoe size such as:

US 9
UK 8
EU 42

is a sizing label.

It is not a guarantee that every shoe carrying that size has exactly the same internal dimensions.

That is why we recommend using three things together:

Your usual size + the specific brand/model size chart + the actual fit of that style.

A conversion chart is very useful, but it should always be treated as a guide rather than an exact measurement.

Coming in Part 3

In Part 3, we’ll look more closely at how half sizes work in Redback boots.
Read Part 3: Redback Boots Sizing: How Half Sizes Really Work

Published by AWB OutletBased on more than 20 years of footwear manufacturing and fitting experience.