Scale is the ratio of the linear dimension of an element of an object as represented in the drawing, to the real linear dimension of the same element of the object itself. Wherever possible, it is desirable to make full size drawings, so as to represent true shapes and sizes. If this is not practicable, the largest possible scale should be used. While drawing very small objects, such as watch components and other similar objects, it is advisable to use enlarging scales.

Designation

The complete designation of a scale should consist of the word Scale, followed by the indication of its ratio as:

SCALE 1 : 1 for full size,

SCALE × : 1 for enlarged scales,

SCALE 1 : × for reduced scales.

The designation of the scale used on the drawing should be shown in the title block.

Recommended Scales

The recommended scales for use on technical drawings are given below. The scale and the size of the object in turn, will decide the size of the drawing.

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Category Recommended Scales
Enlarged scales 50:1 20:1 10:1
5:1 2:1
Full size 1:1
Reduced scales 1:2 1:5 1:10
1:20 1:50 1:100
1:200 1:500 1:1000
1:2000 1:5000 1:10000

Scale Specification

If all drawings are made to the same scale, the scale should be indicated in or near the title block. Where it is necessary to use more than one scale on a drawing, the main scale only should be shown in the title block and all the other scales, adjacent to the item reference number of the part concerned or near the drawings.