Size specification of macromolecular assemblies in the cytoplasm is poorly understood [1]. In principle, assemblies could scale with cell size, or use intrinsic mechanisms to achieve fixed, but regulated, sizes. For the mitotic spindle, scaling with cell size is expected, since the function of this assembly is to physically move sister chromatids into the center of nascent daughter cells. Anecdotally, spindle length does scale with cell length, but it is not clear if this scaling mechanism could operate at very large cell lengths. Eggs of Xenopus laevis are among the largest cells known that cleave completely during cell division. Cell length in this organism changes by two orders of magnitude (~1200 µm to ~12 µm) while it develops from a fertilized egg into a tadpole [2]. We wondered if, and how, mitotic spindle length and morphology adapt to function at these different length scales. Here, we show that spindle length increases with cell length in small cells, but in very large cells spindle length approaches an upper limit of ~60 µm. To transport the DNA into the center of the daughter cells, the relatively small spindle length is compensated by an enormous anaphase B-like movement. Further evidence for an upper limit to spindle length comes from an embryonic extract system that recapitulates mitotic spindle assembly in a test tube. We conclude that early mitotic spindle length in Xenopus laevis is uncoupled from cell length, reaching an upper bound determined by mechanisms that are intrinsic to the spindle.