The ideal gas law combines Boyle's, Charles's, and Avogadro's laws into P = nRT/V.
About this calculator
The ideal gas law combines Boyle's, Charles's, and Avogadro's laws into P = nRT/V. This calculator solves for pressure when you enter moles n, temperature T in kelvin, and volume V in m³.
Example: 1 mol of gas at 298.15 K (25 °C) in 0.0245 m³ (24.5 L) gives P ≈ 101,325 Pa ≈ 1 atm — close to standard conditions. Double the moles at fixed V and T doubles the pressure.
For force on a piston area, combine results with the [[pressure]] calculator (P = F/A). Thermal energy at nuclear scales links to the [[energy-mass]] calculator. Wave properties of matter connect to the [[wavelength]] calculator in advanced courses. The [[work]] calculator helps with expansion work (W = PΔV) in thermodynamics follow-up problems.
Common uses
- Class 11–12 chemistry and physics gas law homework
- Estimating cylinder pressure from moles and volume
- Converting lab conditions to pascals and atm
- Checking STP and RTP textbook examples
- Intro thermodynamics before real-gas corrections
Frequently asked questions
What pressure does 1 mol of gas at 298 K occupy in 0.0245 m³?
P = nRT/V = (1 × 8.314 × 298.15) / 0.0245 ≈ 101,325 Pa ≈ 1 atm. Enter n = 1, T = 298.15, V = 0.0245.
Why must temperature be in kelvin for PV = nRT?
The gas law uses absolute temperature. Convert °C to K by adding 273.15. At 0 K an ideal gas would have zero pressure; Celsius zero does not work in the formula.
How do I convert litres to m³ for volume?
1 L = 0.001 m³. Example: 24.5 L = 0.0245 m³. Enter volume in cubic metres only.
What is R in the ideal gas law?
The universal gas constant R ≈ 8.314 J/(mol·K). This calculator defaults to 8.314462618 — the CODATA value used in physics and chemistry.