Scale Ruler Converter
Convert between drawing measurements and real-world dimensions for architectural drawings, model making, and engineering plans.
| Scale | 1cm on drawing = | Typical Use | Industry |
|---|---|---|---|
| 1:10 | 10cm real | Product design, furniture details | Design |
| 1:20 | 20cm real | Room layouts, joinery details | Architecture |
| 1:25 | 25cm real | UK building drawings standard | Architecture |
| 1:50 | 50cm real | Floor plans, elevations | Architecture |
| 1:100 | 1m real | Building plans, site layouts | Architecture |
| 1:200 | 2m real | Site plans, large buildings | Architecture |
| 1:500 | 5m real | Urban planning, site context | Planning |
| 1:1000 | 10m real | Town planning maps | Planning |
| 1:87 (HO) | 87mm real | Most popular model train scale | Models |
| 1:160 (N) | 160mm real | N gauge model railways | Models |
| 1:76 (OO) | 76mm real | OO gauge (UK standard) | Models |
| 1:48 (O) | 48mm real | O gauge model trains | Models |
How scale drawings work
What scale means: A scale of 1:50 means every 1 unit on the drawing represents 50 units in real life. So 1mm on a 1:50 drawing = 50mm (5cm) in reality. A 10cm measurement on the drawing = 500cm = 5 metres.
Reading a scale ruler: Architectural scale rulers have multiple scales printed along their edges. Each numbered scale corresponds to a different ratio. Always confirm which scale a drawing uses before measuring — it should be stated in the title block.
Architectural scales: In the UK, 1:50 and 1:100 are the most common working scales for floor plans. 1:200 and 1:500 are used for site plans. Detailed sections are typically drawn at 1:20 or 1:10.
Model railway scales: HO (1:87) is the most popular worldwide. OO (1:76) is the UK standard. N gauge (1:160) is popular for larger layouts in limited space. O gauge (1:48) produces larger, more detailed models.
Engineering drawings: Engineering and mechanical drawings often use 1:1 (full size), 1:2, 1:5, 1:10 or 2:1, 5:1, 10:1 for very small parts.