Scaling Blueprint Drawings

Overview

Engineering reference data for Scaling Blueprint Drawings in drawing tools.

Key Formulas

Scale Factor

$SF = \frac{\text{drawing size}}{\text{actual size}}$

Ratio of drawing to real dimensions.

Tolerance

$T = \text{max} - \text{min}$

Allowable variation in dimensions.

Aspect Ratio

$AR = \frac{w}{h}$

Width to height ratio.

Variables

Practical Scaling Examples

SI-Unit Conversion

For a blueprint with scale 1:50, the actual length calculation is: $\text{Actual Length} = \text{Drawing Length} \times \text{Scale Denominator}$

Example: A 1 cm measurement on a 1:50 drawing equals: $(1 \text{ cm}) \times 50 = 50 \text{ cm}$

Imperial Unit Conversion (U.S.)

For a blueprint with scale 1/4", each 1/4" on the plan represents 1' of actual length. Convert the measurement to decimal inches first: $\text{Actual Length (ft)} = \text{Drawing Length (in, decimal)} \times \text{Denominator}$

Example: A 1-3/8" measurement on a 1/4" drawing equals: $(1.375 \text{ in}) \times 4 = 5.5 \text{ ft} = 5' \ 6"$

Commonly Used Drawing Scales

References

• Original Source