Compressibility Factor Calculator: Real Gas Beha...

What is the Compressibility Factor?

The compressibility factor Z measures how much a real gas deviates from ideal gas behavior. For an ideal gas, Z=1. When Z<1, intermolecular attractions dominate (gas is more compressed than expected). When Z>1, repulsive forces dominate (gas is less compressed than expected). Z is critical for accurate engineering calculations at high pressures.

🧪 Compressibility Factor Calculator

Use our free calculator for instant, accurate results.

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📐 Formula

Z = PV / (nRT)

P = pressure (Pa), V = volume (m³), n = moles, R = 8.314, T = temperature (K). For ideal gas: Z = 1. Real gases deviate depending on T and P.

📝 Worked Example

Nitrogen at 100 atm, 300K: Z ≈ 0.996 (≈ideal)
Nitrogen at 300 atm, 300K: Z ≈ 1.10 (repulsive forces dominate)
Van der Waals: (P + an²/V²)(V−nb) = nRT

📝 How to Use the Calculator

Enter GasSelect from common gases or enter Van der Waals constants a and b manually.

Enter P, T, nPressure, temperature, and amount of gas.

Calculate ZView compressibility factor and compare to ideal gas assumption.

View Corrected VolumeSee actual volume vs. ideal volume prediction.

❓ FAQ

What are Van der Waals constants?

'a' corrects for intermolecular attractions; 'b' corrects for finite molecular volume. Different for every gas — listed in standard tables.

When is ideal gas law accurate enough?

At low pressures (<10 atm) and high temperatures, most gases deviate less than 1% from ideal behavior.

What is the Compressibility Factor?