Last Width & Sizing Systems
How UK, US, and EU sizing relate to one another, and how width fittings like A through EEE actually work.
By Ambrogio Shoes Editorial, in consultation with Ambrogio's Spain-based shoemaking team
· Updated July 8, 2026
Shoe sizing runs on three main regional systems — UK, US, and EU (Continental/Paris point) — which use different numerical scales for the same physical foot length, while width fittings (commonly lettered A through EEE, narrow to wide) indicate how much a shoe measures across the ball of the foot at a given length. Because width fitting is relative to length and neither system is universally standardized between brands, the same letter or number can still fit differently depending on the brand's specific last.
Three Regional Systems, One Physical Measurement
Behind every size label is an attempt to describe the same underlying thing: the length of a last. UK and US sizing both use scales historically based on the barleycorn, roughly a third of an inch, though the two systems are offset from each other by about half a size. EU (Continental) sizing instead uses Paris points, each equal to two-thirds of a centimeter, producing yet another numerical scale for the same physical lengths.
Width Letters Add a Second Dimension
Length alone doesn't determine fit — width across the ball of the foot matters just as much. Width fittings are typically expressed with letters, running narrow to wide (commonly A or B through D, E, EE, and EEE), layered on top of a given length size. A size 9 EEE and a size 9 B share the same length but differ significantly in ball width.
Why Brand-to-Brand Comparison Still Requires Care
Neither the length scales nor the width letters are governed by one universal, enforced standard across all brands. Each maker designs its own lasts and applies width and length conventions somewhat independently, which is why the same nominal size and width letter can still feel different from one brand to the next — making a brand's own size guide a more reliable reference than the label alone.
Frequently Asked Questions
Why does my size change between UK, US, and EU labels?
Because each system uses a different unit and starting point to measure the same foot length — UK and US use variations of an inch-based scale (with an offset between them), while EU sizing is based on Paris points, each equal to two-thirds of a centimeter of last length. Converting between them is only ever approximate.
What does a width letter like "D" or "EEE" actually measure?
It reflects how wide the shoe is across the ball of the foot at a specific length, using a lettered scale that typically runs from narrower (A, B) to wider (D, E, EE, EEE), though the exact width in millimeters for a given letter varies by brand and by country convention (UK and US width scales aren't identical either).
Is a size 9 D always the same width in every brand?
No — width fitting is specific to each brand's own last, so a 9 D from one maker can measure differently across the ball than a 9 D from another. Width letters are a useful relative guide within a brand's own range, but not a precise universal standard.
What's the safest way to find my true size across brands?
Rely on a brand's specific size guide or fit notes rather than assuming your usual size and width will translate directly, and where possible use an in-person or virtual fitting to check both length and width against that brand's particular last.
Sources & further reading:
Shoegazing — A Guide to Shoe Sizing Systems: https://shoegazing.com/
