Tested a 2-stage model of magnitude estimation with 36 undergraduates who compared the subjective magnitude of weights with the integers 1-9. Scale values for number and weight were obtained from a nonmetric solution to a conjoint scaling model. It was assumed in the solution that the frequency with which numbers were judged greater than weights was monotonic with the difference in their scale values. The relations between subjective number and objective number and between subjective weight and physical weight were each power functions. The ratio of exponents for weight (.57) and number (.63) predicted the exponent for magnitude estimation of weight (.90) obtained from the same Ss. Results support the hypotheses. (16 ref.) (PsycINFO Database Record (c) 2006 APA, all rights reserved)