Fluid Love number and normalised moment of inertia Ñ for a random ensemble of 5 × 10⁵ models with a number of layers 2 ≤ L ≤ 10. The solid red line shows the ROT . The dashed red line represents the Radau-Darwin (RD) formula (e.g. Cook 1980; Padovan et al. 2018; Ragazzo 2020). The RD formula is exact for a homogeneous body, but it constitutes an approximation for layered planets (Kramm et al. 2011; Padovan et al. 2018). The ROT and RD formulas match for ; for smaller values, our ROT represents a more rigorous upper limit to Ñ. The blue dot corresponds to values of and Ñ for a polytrope of index one, while the green triangle corresponds to the results by Wahl et al. (2020) for the equilibrium tidal response of Jupiter.