OO Scale (1:76) Calculator & Conversion Chart
UK railway standard · 1.32% of real size
OO is Britain’s dominant railway scale at 1:76.2 — 4 mm to the foot. Quirk worth knowing: OO runs on the same 16.5 mm track as HO, which is technically narrow for the scale, so HO track and OO stock have mixed for decades.
Precision Scale Conversion Calculator
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OO Scale (1:76) Quick Facts
- 1 real foot = 0.158″ (4.01 mm) on the model
- 1 real meter = 13.16 mm on the model
- A 6 ft (183 cm) person = 24.1 mm (0.95″) tall
- Model is 1.32% of real size — use this as the scale percentage in 3D-print slicers
OO Scale (1:76) Reference Chart
| Real Size | mm | cm | inches |
|---|---|---|---|
| 1 inch | 0.334 mm | 0.033 cm | 0.013″ |
| 1 foot | 4 mm | 0.401 cm | 0.158″ |
| 6 ft (person) | 24.1 mm | 2.41 cm | 0.947″ |
| 1 meter | 13.2 mm | 1.32 cm | 0.518″ |
| 3 m (room height) | 39.5 mm | 3.95 cm | 1.554″ |
| 10 meters | 131.6 mm | 13.16 cm | 5.18″ |
| 30 m (building) | 394.7 mm | 39.47 cm | 15.541″ |
Frequently Asked Questions
What is OO scale in mm, cm, and inches?
In OO Scale (1:76), 1 unit on the model equals 76 of the same unit in real life. One real foot equals 0.158 inches (4.01 mm) on the model, one real meter equals 13.16 mm (1.32 cm), and the model is 1.32% of real size.
How tall is a 6 ft person in OO Scale (1:76)?
A 6-foot (183 cm) person stands 24.1 mm (0.95 inches) tall in OO Scale (1:76).
How do I convert a real measurement to OO Scale (1:76)?
Divide the real measurement by 76. For example, a 10 m object is 131.6 mm long in OO Scale (1:76). The calculator on this page does this automatically in both directions.