Ideal Gas Law Calculator

Calculate pressure, volume, temperature, or moles using PV=nRT

Gas Law Equation: PV = nRT

P × V = n × R × T

Pressure × Volume = Moles × Gas Constant × Temperature

About the Ideal Gas Law

What is the Ideal Gas Law?

The ideal gas law is an equation of state that describes the behavior of an ideal gas. It relates the pressure, volume, temperature, and amount (moles) of a gas through the equation PV = nRT.

Variables

  • P = Pressure (atm, kPa, mmHg, torr, Pa)
  • V = Volume (Liters)
  • n = Number of moles (mol)
  • R = Gas constant (varies by units)
  • T = Temperature (Kelvin)

Gas Constant (R) Values

  • 0.08206 L·atm/(mol·K) - Most common
  • 8.314 J/(mol·K) - SI units
  • 8.314 L·kPa/(mol·K)
  • 62.364 L·mmHg/(mol·K) or L·torr/(mol·K)

Standard Temperature and Pressure (STP)

At STP (0°C or 273.15 K, 1 atm), one mole of an ideal gas occupies 22.4 liters. This is a useful reference point for gas calculations.

Temperature Conversions

  • Kelvin (K) = Celsius (°C) + 273.15
  • Kelvin (K) = (Fahrenheit (°F) + 459.67) × 5/9
  • Always use Kelvin in gas law calculations

Example Problem

Question: What is the pressure of 1 mole of gas at 273.15 K in a 22.4 L container?
Solution: P = nRT/V = (1 mol)(0.08206 L·atm/(mol·K))(273.15 K) / (22.4 L) = 1.00 atm

Applications

  • Chemistry stoichiometry problems
  • Gas behavior predictions
  • Engineering calculations
  • Atmospheric science
  • Scuba diving calculations
  • Weather balloon design

Limitations

The ideal gas law assumes gases behave ideally (no intermolecular forces, negligible molecular volume). Real gases deviate from ideal behavior at high pressures and low temperatures. For more accurate results with real gases, use the Van der Waals equation.