Scale Conversion Calculator

Convert real-world dimensions to model scale dimensions. Supports common model scales like HO (1:87), N (1:160), O (1:48), and more.

Real Dimension

Scale Denominator

Input Unit

Model Size (inches)

0.828

Model Size (mm)

21.02

Scale Factor

0.0115

Model-to-Real Ratio

1:87

How to Use This Calculator

Enter Real Dimension, Scale Denominator, and Input Unit.
Select the Input Unit — Inches, Feet, Millimeters, or Meters — to match how your real dimension is measured.
Set Scale Denominator to your target scale (e.g., 87 for HO, 160 for N).
Review Model Size (inches) and Model Size (mm).
Use Scale Factor and Model-to-Real Ratio to inform your decision.

How the result changes with Scale Denominator

Real Dimension: The real-world dimension to convert to model scale
Scale Denominator: The scale ratio denominator (e.g., 87 for 1:87 HO scale, 160 for N scale)
Input Unit: Unit of the real-world measurement

Identify Input Parameters
Real Dimension = 72, Scale Denominator = 87, Input Unit = 1 = 3 input(s) provided
Calculate Model Size
Model Size
0.828 = 0.828
Calculate Model Size
Model Size
21.02 = 21.02
Calculate Scale Factor
Scale Factor
0.0115 = 0.0115
Calculate Model-to-Real Ratio
Model-to-Real Ratio
87 = 87

Engine last updated August 6, 2026. Checked against 2 independently-derived tests — how we verify calculators.

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