Size system

A size system is a shared way of naming sizes: US, UK and EU dress numbers, letters from XS to XXL, the UK, US and EU shoe scales, bra bands in inches or centimeters. Each names the same bodies, or the same products, with its own numbers.

None of them is a measurement. The same body is a US 8 to 10, a UK 12 to 14 and an EU 40 to 42, and each label is right in its own system. That is why a chart needs the measurements, and treats the systems as names for them.

On a size chart

Systems sit on their own rows or columns, one per system, next to the measurements. Some examples from Ruban Size's templates and engine:

Shoes count differently in each system: UK and US sizes in barleycorns of a third of an inch, EU sizes in Paris points of two thirds of a centimeter, Japanese sizes in centimeters of foot length. Their numbers never line up neatly, so every conversion is approximate and a brand's own chart wins. Women's clothing sizes compared shows how the dress systems line up.

In Ruban Size

In the size chart editor, mark a row or column as a size system (US, UK, EU...) and shoppers get a switch above the table. The first system shown follows the shopper's country: US in the United States, UK in Great Britain and Ireland, EU elsewhere. For bras, Find my size answers in the chart's own system, then lists "The same size in other systems" across all seven.