Calculate gas pressure using P = nRT/V. Find pressure from moles, temperature, and volume with multi-unit output and gas property calculations.
The **Ideal Gas Pressure Calculator** determines the pressure of a gas using P = nRT/V from the ideal gas law. Given the number of moles, temperature, and container volume, it computes pressure in all common units — kPa, atm, bar, psi, and mmHg.
Pressure calculations are critical for gas storage design, laboratory experiments, chemical process engineering, and safety analysis. A seemingly small amount of gas can generate enormous pressure in a small container — 1 mole of gas at room temperature in a 1-liter bottle produces about 24.5 atm (360 psi), well beyond the burst pressure of a glass container.
This calculator provides instant multi-unit pressure results with a gas database for mass and density calculations, a moles-vs-pressure chart, and reference table showing how pressure varies with the amount of gas. Check the example with realistic values before reporting. Use the steps shown to verify rounding and units. Cross-check this output using a known reference case.
Quick and accurate pressure calculations are essential for laboratory planning, gas cylinder safety, and process engineering. This calculator handles all common units and provides supporting data including mass, density, and molecule count. Keep these notes focused on your operational context. Tie the context to the calculator’s intended domain. Use this clarification to avoid ambiguous interpretation.
P = nRT / V Where: P = pressure (Pa), n = moles, R = 8.31446 J/(mol·K), T = temperature (K), V = volume (m³)
Result: 247.9 kPa (2.447 atm)
P = (1 mol)(8.31446)(298.15 K) / (0.01 m³) = 247,897 Pa = 247.9 kPa = 2.447 atm. One mole in 10 L at room temperature produces about 2.4 atmospheres of pressure.
Gas pressure arises from the kinetic energy of molecules colliding with container walls. The ideal gas law quantifies this: P = nRT/V. Each variable directly influences pressure — more gas (n↑), higher temperature (T↑), or smaller volume (V↓) all increase pressure.
Understanding this relationship is crucial for safety. Gas cylinders are rated for specific maximum pressures. Heating a sealed container increases pressure — a cylinder at 2,000 psi at 20°C reaches 2,170 psi at 45°C, which could exceed safety margins if not accounted for.
**Chemical Processing:** Reactor pressure determines reaction rates and equilibrium positions. Many industrial processes (ammonia synthesis, polyethylene production) operate at extreme pressures (100-1000 atm) to drive reactions forward.
**Gas Storage:** Compressed natural gas (CNG) vehicles store fuel at 200-250 atm. Liquid petroleum gas (LPG) stays liquid at modest pressures (5-10 atm at room temperature). Hydrogen storage for fuel cells requires either very high pressure (700 atm) or cryogenic temperatures.
Pressure vessel design follows strict engineering codes (ASME, PED) with safety factors of 3-4× the maximum expected operating pressure. Pressure relief valves prevent catastrophic failure from temperature increases, accidental overfilling, or runaway reactions. Regular hydrostatic testing ensures vessel integrity throughout their service life.
Pressure doubles (at constant T and V). This is a direct proportionality from PV = nRT — more molecules means more collisions with the walls.
Higher temperature means faster molecules, which hit the walls harder and more often, increasing pressure. This is Gay-Lussac's Law: P/T = constant at fixed n and V.
Absolute pressure is the total pressure. Gauge pressure is absolute minus atmospheric (101.325 kPa). A tire at "35 psi" gauge is actually 35 + 14.7 = 49.7 psi absolute.
Above ~10 atm for most gases, deviations become significant (>1%). At hundreds of atmospheres, the van der Waals or other equations of state are needed for accuracy.
Each gas in a mixture contributes partial pressure: Pi = (ni/ntotal) × Ptotal. The total pressure is the sum of all partial pressures (Dalton's Law).
Absolute pressure cannot be negative. However, gauge pressure can be negative (vacuum). A perfect vacuum is 0 Pa absolute or -101.325 kPa gauge.