Enter a scale ratio and a dimension to convert between real-world and scale-model size.
How to Use the Scale Conversion Calculator
Set the scale ratio as two numbers (1:48, 1:87, 1:24 — whatever the model calls for), pick Real → Model or Model → Real, and enter the known dimension. The result is unitless — it works the same whether that dimension is in inches, centimeters, or feet, so long as the answer gets read back in that same unit.
model = real × (scale numerator ÷ scale denominator)
real = model ÷ (scale numerator ÷ scale denominator)Model railroading, dollhouses, and architectural scale models each settled on their own conventional ratios — 1:87 (HO scale) for trains, 1:12 for dollhouses, 1:48 for a common architectural scale — but the arithmetic connecting a real object to its miniature is identical across all of them. A 96-inch real wall at 1:48 becomes a 2-inch model wall; run the same ratio backwards and a 2-inch model part scales up to an 8-foot real one.