Understanding 1:20 Scale
The 1:20 scale is a proportional ratio where every 1 unit of measurement on your drawing, model, or plan represents exactly 20 of those same units in the real world. This makes 1:20 a large-scale representation, meaning objects appear relatively large on paper.
For example, 1 mm on a 1:20 drawing represents 20 mm (2.0 cm) in reality. Conversely, a real-world measurement of 1 meter would appear as 50.0 mm on a 1:20 scale drawing.
1:20 Scale Quick Reference Table
Common conversions at 1:20 scale for quick reference.
| Real World | On Drawing (1:20) | Imperial Equivalent |
|---|---|---|
| 0.5 m | 25.0 mm | 25.00 thou |
| 1 m | 50.0 mm | 1.97″ |
| 2 m | 100.0 mm | 3.94″ |
| 5 m | 250.0 mm | 9.84″ |
| 10 m | 500.0 mm | 19.69″ |
| 25 m | 1250.0 mm | 49.21″ |
| 50 m | 2500.0 mm | 98.43″ |
| 100 m | 5000.0 mm | 196.85″ |
When to Use 1:20 Scale
The 1:20 scale is a standard in engineering work. Here are the most common applications:
- Structural connections
- Pipe assemblies
- Equipment details
How to Convert 1:20 Scale Step by Step
- 1Identify the scale ratio. You are working with 1:20, which means the drawing is 20× smaller than reality.
- 2Real → Scaled: Divide the real measurement by 20. Example: 500 mm = 25.0 mm on paper.
- 3Scaled → Real: Multiply the drawing measurement by 20. Example: 20 mm on drawing = 400 mm (0.40 m) in reality.
1:20 Scale FAQ
- What does 1:20 scale mean?
- A 1:20 scale means that 1 unit on your drawing or model represents 20 of the same units in real life. For example, 1 mm on a 1:20 drawing equals 20 mm in reality.
- How do I convert real measurements to 1:20 scale?
- To convert a real-world measurement to 1:20 scale, divide the real measurement by 20. For instance, a real wall that is 500 mm long would be drawn as 25.0 mm on a 1:20 drawing.
- How do I convert 1:20 scale back to real size?
- Multiply the measurement on your 1:20 drawing by 20 to get the real-world size. If something measures 20 mm on your drawing, the real size is 400 mm (0.40 m).
- What is 1:20 scale used for?
- The 1:20 scale is commonly used in engineering applications. It is ideal for representing objects and spaces at a manageable size while maintaining proportional accuracy.
- Is 1:20 scale metric or imperial?
- Scale ratios like 1:20 are unit-independent — they work with any measurement system. Whether you measure in millimeters, centimeters, inches, or feet, the ratio remains the same: 1 unit on paper equals 20 units in reality.
Popular 1:20 Conversions
Quick links to specific unit conversions at 1:20 scale.