1:20 Scale Calculator & Conversion Chart
Interior detail scale · 5% of real size
1:20 is the architect’s detail scale — furniture layouts, joinery, and interior elevations where a 5 cm shelf thickness must still read clearly at 2.5 mm. It is also, coincidentally, a major garden railway ratio (1:20.3 "Fn3").
Precision Scale Conversion Calculator
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1:20 Scale Quick Facts
- 1 real foot = 0.6″ (15.24 mm) on the model
- 1 real meter = 50 mm on the model
- A 6 ft (183 cm) person = 91.5 mm (3.6″) tall
- Model is 5% of real size — use this as the scale percentage in 3D-print slicers
1:20 Scale Reference Chart
| Real Size | mm | cm | inches |
|---|---|---|---|
| 1 inch | 1.3 mm | 0.127 cm | 0.05″ |
| 1 foot | 15.2 mm | 1.52 cm | 0.6″ |
| 6 ft (person) | 91.4 mm | 9.14 cm | 3.6″ |
| 1 meter | 50 mm | 5 cm | 1.969″ |
| 3 m (room height) | 150 mm | 15 cm | 5.906″ |
| 10 meters | 500 mm | 50 cm | 19.685″ |
| 30 m (building) | 1500 mm | 150 cm | 59.055″ |
Frequently Asked Questions
What is 1:20 scale in mm, cm, and inches?
In 1:20 Scale, 1 unit on the model equals 20 of the same unit in real life. One real foot equals 0.6 inches (15.24 mm) on the model, one real meter equals 50 mm (5.00 cm), and the model is 5% of real size.
How tall is a 6 ft person in 1:20 Scale?
A 6-foot (183 cm) person stands 91.5 mm (3.6 inches) tall in 1:20 Scale.
How do I convert a real measurement to 1:20 Scale?
Divide the real measurement by 20. For example, a 10 m object is 500.0 mm long in 1:20 Scale. The calculator on this page does this automatically in both directions.