Scale

Scale is how a building or a landscape is reduced by a fixed ratio so that it fits on paper. At 1:100, each unit on the drawing represents a hundred units in reality, so one centimetre on the sheet is one metre on site. Larger scales such as 1:50 or 1:20 show more detail; smaller scales such as 1:500 or 1:1000 cover a wider area.

Which drawing at which scale?

• Urban and regional plans: small scales such as 1:5000 or 1:1000
• Site plans: usually 1:500 or 1:200
• Preliminary design: typically 1:100 or 1:200
• Construction documents: commonly 1:50
• Wall build-ups and junction details: 1:20, 1:10, 1:5 and 1:1

These are common metric conventions; imperial drawings use their own scales, such as a quarter inch to the foot.

Scale and drawing language

Scale is not only a ratio; it decides how much information a drawing can hold. On a 1:200 plan a wall is a single thick line; at 1:50, plaster, insulation and brick each appear separately. That is why line weights, hatching and text sizes change with scale.

In digital models everything is drawn at full size and scale is only chosen when printing. Drawing scale should not be confused with human scale: one is the ratio of a drawing, the other is how a space feels relative to the human body.