Ideal Gas Pressure Calculator — PV = nRT
Find the absolute pressure exerted by an ideal gas given its amount in moles, absolute temperature and volume. The calculator uses the ideal gas law P = nRT/V and returns results in Pa, atm, kPa, bar and psi — plus the molar volume at those conditions.
mol
K
L
Absolute pressure of the ideal gas in pascals
- 1
Volume (L → m³)
V = 22.414 ÷ 1 000 = 0.022414Convert litres to cubic metres so units are consistent with Pa and J/(mol·K). - 2
Numerator n × R × T
1 × 8.314462618 × 273.15 = 2,271.0955 - 3
Pressure P = nRT / V
2,271.0955 ÷ 0.022414 = 101,324.86
How does this calculator work?
P = nRT/V from the ideal gas law, where R = 8.314 J/(mol·K), T is in kelvin and V is in m³ (or litres / 1000). One mole of ideal gas at 0 °C occupies 22.414 L at exactly 1 atm. Pressure scales linearly with moles and temperature, and inversely with volume.
Formula
How this is calculated
The ideal gas law PV = nRT relates four state variables of a gas sample: pressure P (Pa), volume V (m³), amount n (mol) and absolute temperature T (K), with the universal gas constant R = 8.314 462 618 J/(mol·K). Rearranging for pressure gives P = nRT / V. The calculator accepts volume in litres (1 L = 0.001 m³) and converts internally before computing.
A classic check: 1 mol of ideal gas at 0 °C (273.15 K) in a volume of 22.414 L should give P = 1 × 8.314 × 273.15 / 0.022414 ≈ 101 325 Pa = 1 atm — matching the definition of standard temperature and pressure (STP). At SATP (25 °C, 1 bar) the molar volume increases slightly to 24.789 L/mol.
The ideal gas model assumes point-like molecules with no intermolecular attractions or repulsions and perfectly elastic collisions. It is highly accurate at low-to-moderate pressures (below ~10 bar) and high temperatures relative to the gas's critical temperature. At high pressures or near condensation, real gas equations (van der Waals, Peng–Robinson) are needed. The calculator computes pressure in five common units so results can be compared to gauge readings or literature values directly.
Frequently asked questions
P = 2 × 8.314 × 298.15 / 0.050 = 4 958 / 0.050 ≈ 99 166 Pa ≈ 0.979 atm. Enter n = 2, T = 298.15, V = 50 in the calculator to verify.
Add 273.15 to the Celsius value: 0 °C = 273.15 K; 25 °C = 298.15 K; 100 °C = 373.15 K. The ideal gas law always requires absolute temperature in kelvin — using Celsius directly gives wrong answers.
1 atm = 101 325 Pa (exact by definition). 1 bar = 100 000 Pa; 1 kPa = 1 000 Pa; 1 psi ≈ 6 894.76 Pa. The calculator returns pressure in all five units simultaneously.
TG we-Calculate Editorial Team. (2026). Ideal Gas Pressure Calculator — PV = nRT [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/ideal-gas-pressure-calculator
TG we-Calculate Editorial Team. "Ideal Gas Pressure Calculator — PV = nRT." TG we-Calculate. 2026. https://we-calculate.com/calculator/ideal-gas-pressure-calculator.
TG we-Calculate Editorial Team, "Ideal Gas Pressure Calculator — PV = nRT," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/ideal-gas-pressure-calculator
@misc{wecalculate_ideal_gas_pressure_calculator, title = {Ideal Gas Pressure Calculator — PV = nRT}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/ideal-gas-pressure-calculator}}, year = {2026}, note = {TG we-Calculate} }
Did this calculator help you?