Scale Calculator

Convert between real size and scaled size for models, drawings and maps using any scale ratio such as 1:50 or 1:100.

Part of:Conversions hub

How to Use This Calculator

How to Use

  1. Choose whether you are scaling a real size down to drawing size, or reading a real size up from a drawing.
  2. Enter the measurement in any consistent unit.
  3. Enter the scale factor — for a 1:50 drawing, enter 50.

How scale works

A scale of 1:50 means one unit on the drawing represents 50 units in real life. To get the drawing size, divide the real size by the scale factor. To get the real size, multiply the drawing measurement by the scale factor.

Common scales

Architectural plans often use 1:50 and 1:100, site plans 1:200 or 1:500, and maps 1:1250 up to 1:25000. Model kits use scales such as 1:24, 1:48 and 1:72.

Common Questions

What does a scale of 1:50 mean?

It means one unit on the drawing equals 50 of the same units in real life. So 10mm on a 1:50 plan represents 500mm, or half a metre, in reality.

How do I convert a drawing measurement to real size?

Multiply the measurement you take off the drawing by the scale factor. On a 1:100 plan, 35mm measured equals 3,500mm or 3.5m in real life.

How do I scale a real size down for a drawing?

Divide the real size by the scale factor. A 6m wall at 1:50 becomes 120mm on the drawing (6000 divided by 50).

What units does the scale calculator use?

Any unit, as long as you stay consistent. The scaled and real results come out in the same unit you enter.

What scale is used for maps?

Common map scales include 1:1250 and 1:2500 for detailed local plans, and 1:25000 or 1:50000 for Ordnance Survey leisure maps.

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