Furthermore, we see that both swelling models accurately describe swelling of weakly crosslinked PNIPAM-co-PAA microgels, when varying microgel concentration. Comparison against experiments for microgels with typical size of a few hundreds of nanometers shows that both elastic models predict approximately similar swelling with almost indistinguishable estimations, in accordance with the limiting behavior of Langevin model for large polymerisation degree, N ≫ 1.