Although there is this differential (?) ideal gas law, Lenard mentioned, I think the Boltzman constant should not be defined as shown below, as it uses K as unit and currently multiplicative K is used in the library for relative temperature.   I have no easy idea, how to formulate it differently, as R itself is something like a quantitive_point (inherited by the absolute temperature difference) and multiplications with it are not allowed.   Perhaps an absolute temperature as a quantity (instead of a quantity point) is needed after all?   -----Ursprüngliche Nachricht----- Von:Lénárd Szolnoki via Std-Proposals <std-proposals_at_[hidden]> Gesendet:Di 18.06.2024 15:42 Betreff:Re: [std-proposals] On the standardization of mp-units P3045R1 An:std-proposals_at_[hidden]; CC:Lénárd Szolnoki <cpp_at_[hidden]>; > quantity R_boltzman = 8.314 * N * m / (K * mol); There is an analogous Δp V = nRΔT equation, where Δp is pressure-change and ΔT is temperature-change. Here the 1°C = 1K unit conversion is the correct one.