Category:Twelves scales

The "Twelves" scales emerged from a period of model-building in which the dominant system of measures was pre-metric.

The idea of building models that have precise, fixed-ratio relationships to their originals is a pleasing one, and it's also useful to have a reduced range of standardised default scales, so that different models that need to be at approximately the same scaling end up by default with precisely the same scaling.

Ratio scaling

Powers of two, and multiples of two, three, five, six, ten are obvious choices for a scale standard, but in a pre-calculator age, where sizes and part dimensions were specified British Imperial units or their US equivalents ... which were predominantly based around base twelve (twelve inches to a foot) rather than ten, calculations were simplified if the scaling factors were also multiples of twelve. Modelmakers also found that standard raw materials that they used to build their models (such as wire, or metal plate) tended to be supplied in sizes specified in fractions of an inch, making "twelvelike" scaling factors even more useful.

With "1:12", "Doll's House" scale, sizes in feet on the original object mapped simply to the same numerical measurements in inches on the model, and a room's dimensions in feet became the model's dimensions in inches. With 1:24 scale, a foot corresponded to half an inch, with 1:48, a foot corresponded to a quarter-inch, and with 1:72, a foot corresponded to one sixth of an inch, and a six-foot human character was exactly one inch tall.