Drawing scales and AutoCAD SCALE factors
Convert drawing lengths and distinguish geometry scaling from viewport and printing settings.
What 1:n means
A scale of 1:n means one drawing unit represents n real units. With units aligned, real length equals drawing length × n, and drawing length equals real length/n. At 1:100, a 50 mm drawing length represents 5,000 mm or 5 m.
Denominators and enlargement
Changing from 1:100 to 1:50 makes the same object twice as large on paper. The required length factor is the old denominator divided by the new one: 100/50 = 2. Reversing the change gives 0.5. Different drawing units require an additional unit conversion.
Model space versus output scale
For geometry drawn at real size, preserve the model and normally manage presentation scale through layouts, viewports and plot settings. Rescaling an already scaled object is different from changing how a full-size model is printed. Check the drawing standard and units before using SCALE.
Check the result
Measure a known reference length after conversion. Text, dimension styles, linetype scale and annotation scale may be managed separately from geometry. When checking a PDF or printout, confirm that fit-to-page options have not introduced an additional scale factor.