The equilibrium swelling degree of poly(N,N-dimethylacylamide) (polyDMAAm)-based gels; In water was systematically studied with various initial monomer (c(m)) and cross-linker (c(xl)) concentrations, and as a function of initial concentration of fully ionized co-monomer, 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS). Proportionality of the length of a subchain (N) in the gels to [c(xl)(c(m)+c(xl))](-1) was revealed, both theoretically and experimentally. Equilibrium swelling data indicate non-Gaussian elasticity of the gel network.