We prove a lower bound for the free energy (per unit volume) of the twodimensional Bose gas in the thermodynamic limit. We show that the free energy at density ρ and inverse temperature β differs from the one of the non-interacting system by the correction term 4πρ 2 | ln a 2 ρ| −1 (2−[1−β c /β] 2 + ). Here a is the scattering length of the interaction potential, [·] + = max{0, ·} and β c is the inverse Berezinskii-Kosterlitz-Thouless critical temperature for superfluidity. The result is valid in the dilute limit a 2 ρ 1 and if βρ 1.2. The lower bound on the o(1) error term given here is uniform in βρ as long as βρ 1. The proof will show that the actual error rate is much better for βρ some distance away from β c ρ (either above or below), see (2.16.13). For very low temperatures, we utilize the proof method of [30]; this way, we recover the ground state energy error rate | ln a 2 ρ| −1/5 for very low temperatures, which was proved for T = 0 in [30].6