Abstract. In the convergence theory of rational interpolation and Padé approximation, it is essential to estimate the size of the lemniscatic set E := z : |z| ≤ r and |P (z)| ≤ n , for a polynomial P of degree ≤ n. Usually, P is taken to be monic, and either Cartan's Lemma or potential theory is used to estimate the size of E, in terms of Hausdorff contents, planar Lebesgue measure m 2 , or logarithmic capacity cap. Here we normalize P L∞ |z|≤r = 1 and show that cap(E) ≤ 2r and m 2 (E) ≤ π(2r ) 2 are the sharp estimates for the size of E. Our main result, however, involves generalizations of this to polynomials in several variables, as measured by Lebesgue measure on C n or product capacity and Favarov's capacity. Several of our estimates are sharp with respect to order in r and . §1. IntroductionIn the convergence theory of Padé approximation, and more generally rational interpolation, an essential ingredient is an estimate on the size of the lemniscatewhere P is a polynomial of degree ≤ n. There are several ways to provide this estimate. Cartan's Lemma shows that if P is normalized to be monic of degree n, then we can cover this set by a union of ≤ n balls B j , 1 ≤ j ≤ , whose diameters d(B j ) satisfy, for a given α > 0,The remarkable thing about the estimate is its independence of the degree of P . See [1, p. 194