The Gas Density Calculator computes the density of a gas using the Ideal Gas Law (ρ=P MR T\rho = \dfrac{P\,M}{R\,T}ρ=RTPM​), where PPP is pressure, MMM is molar mass, RRR the gas constant, and TTT temperature. For non-ideal conditions you can enable an optional Van der Waals solver (requires aaa and bbb parameters in SI units) — the tool numerically solves for density using a robust bisection method. It supports common pressure units (Pa, kPa, bar, atm, psi), temperature units (K, °C), and outputs density in kg/m³ or g/L. This single-file, responsive HTML is WordPress-safe and ideal for students, lab work, and engineering estimates.