The similarity ratio, or scale factor, of two similar figures is the common ratio 
of corresponding lengths. Corresponding
areas then have ratio 
, and corresponding volumes have
ratio 
.
A similarity ratio of 1 gives congruent figures.
Similarity Ratio
See also
Congruent Polygons, Ratio of Magnification, Similar, Similar Polygons, SimilarityExplore with Wolfram|Alpha
References
Coxeter, H. S. M. and Greitzer, S. L. Geometry Revisited. Washington, DC: Math. Assoc. Amer., 1967.Cite this as:
Weisstein, Eric W. "Similarity Ratio." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/SimilarityRatio.html