🧪 Ideal Gas Law Calculator
Calculate the unknown variable in the ideal gas law equation PV = nRT. Solve for Pressure (P), Volume (V), Temperature (T), or Amount of substance (n) using the appropriate gas constant. Perfect for chemistry and physics students, researchers, and engineers.
What Is the Ideal Gas Law?
The ideal gas law is a fundamental equation in thermodynamics that describes the relationship between pressure, volume, temperature, and the amount of an ideal gas. It is expressed as:
PV = nRT
where P = pressure, V = volume, n = amount of substance (moles), R = ideal gas constant, T = absolute temperature
The ideal gas law combines several simpler gas laws:
- Boyle's Law: P ∝ 1/V (at constant n and T)
- Charles's Law: V ∝ T (at constant n and P)
- Avogadro's Law: V ∝ n (at constant P and T)
- Gay-Lussac's Law: P ∝ T (at constant n and V)
The ideal gas law is accurate for most gases at low pressure and high temperature. At high pressure or low temperature, real gases deviate from ideal behavior due to intermolecular forces and molecular volume.
How to Use This Calculator
This calculator allows you to solve for any of the four variables in the ideal gas law:
- Pressure (P): Enter V, n, T, and select R. The calculator will compute P.
- Volume (V): Enter P, n, T, and select R. The calculator will compute V.
- Temperature (T): Enter P, V, n, and select R. The calculator will compute T.
- Amount (n): Enter P, V, T, and select R. The calculator will compute n.
Simply select the variable you want to solve for, enter the known values, choose the appropriate gas constant, and click "Calculate". The calculator will show the step-by-step solution.
Why Use This Calculator?
- Instant results: Solve for any variable in the ideal gas law in real-time.
- Multiple units: Enter pressure, volume, and temperature in your preferred units.
- Gas constant selection: Choose the appropriate R value for your unit system.
- Step-by-step breakdown: See exactly how the calculation is performed.
- Free & private: No registration, no data storage — all calculations are done in your browser.
❓ Ideal Gas Law Calculator FAQ
What is the ideal gas law equation?
The ideal gas law is PV = nRT, where P is pressure, V is volume, n is the number of moles, R is the gas constant, and T is the absolute temperature (in Kelvin).
What is the gas constant R?
The gas constant R has different values depending on the units used. The most common values are 8.314462618 J/(mol·K) (SI) and 0.082057366 L·atm/(mol·K).
What is STP?
STP (Standard Temperature and Pressure) is defined as 0°C (273.15 K) and 1 atm. At STP, one mole of an ideal gas occupies 22.414 L.
What is the difference between STP and SATP?
STP is 0°C and 1 atm (22.414 L/mol). SATP (Standard Ambient Temperature and Pressure) is 25°C and 1 bar (24.789 L/mol).
When is the ideal gas law accurate?
The ideal gas law is accurate for most gases at low pressure (below a few atmospheres) and high temperature (well above the boiling point).
What is the difference between an ideal gas and a real gas?
An ideal gas has no intermolecular forces and occupies no volume. A real gas has intermolecular forces and finite molecular volume, which cause deviations from the ideal gas law.
How do I convert Celsius to Kelvin?
To convert Celsius to Kelvin, add 273.15: K = °C + 273.15.
How accurate is this calculator?
This calculator provides highly accurate results using the standard ideal gas law equation. Accuracy depends on the precision of the input values. You can adjust the decimal precision in the output.
Is this calculator free?
Yes, this calculator is completely free to use. No registration or personal data storage is required.
What units does this calculator support?
Pressure: Pa, kPa, bar, atm, psi, mmHg. Volume: m³, L, mL, ft³, gal. Temperature: K, °C, °F. Amount: moles.