Enter calculation details
Choose the variable to solve. Leave that specific input blank and provide the other required state values.
Example data table
| Case | Known Inputs | Unknown | Expected Insight |
|---|---|---|---|
| Standard molar volume | P = 1 atm, n = 1 mol, T = 273.15 K | V | Volume approaches 22.414 L. |
| Laboratory cylinder | V = 10 L, n = 2 mol, T = 298.15 K | P | Pressure rises with warmer confined gas. |
| Mole estimation | P = 200 kPa, V = 0.015 m³, T = 320 K | n | Moles quantify stored gas amount. |
| Thermal state recovery | P = 150 kPa, V = 5 L, n = 0.25 mol | T | Temperature reveals system energy level. |
Formula used
Primary relation: PV = nRT
Pressure form: P = nRT / V
Volume form: V = nRT / P
Moles form: n = PV / RT
Temperature form: T = PV / nR
The calculator converts every input into SI units first. Pressure becomes pascals, volume becomes cubic meters, temperature becomes kelvin, and amount becomes moles.
It then applies the universal gas constant, R = 8.314462618 Pa·m³/(mol·K). This maintains consistent dimensional balance before converting results into your chosen display units.
When molar mass is supplied, density is estimated by ρ = PM / RT. This is useful for quick engineering checks, gas handling estimates, and laboratory planning.
How to use this calculator
- Choose the variable you want to calculate.
- Enter the other three known gas state values.
- Select units for both input and output fields.
- Add molar mass if you also want density.
- Set the decimal precision that suits your report.
- Press the calculate button to display results above the form.
- Use the CSV or PDF buttons to export the summary.
- Check the formula and assumption note before final decisions.
Frequently asked questions
1. What does the ideal gas law calculate?
It links pressure, volume, temperature, and amount of gas. When any three are known, the fourth can be estimated under ideal gas assumptions.
2. Why must temperature be absolute?
The equation requires temperature on an absolute scale. The calculator converts Celsius, Fahrenheit, and Rankine into kelvin before solving the relationship.
3. When is the ideal gas model accurate?
It works best at moderate pressure and sufficiently high temperature, where intermolecular forces and gas volume effects remain small.
4. Can I use gauge pressure values?
No. Convert gauge pressure into absolute pressure first. The gas law depends on absolute thermodynamic pressure, not relative pressure.
5. Why does the calculator support many units?
Scientists and engineers use different measurement systems. Unit conversion helps you compare laboratory data, field readings, and textbook examples consistently.
6. What is the density output based on?
Density is derived from pressure, temperature, and molar mass using ρ = PM / RT. Supply molar mass to activate that estimate.
7. Does molecule count change with unit choices?
No. Molecule count depends only on the calculated number of moles. Unit selections only change how the values are displayed.
8. Can I use this for real gases?
Use it for quick approximations. For high-pressure or strongly interacting gases, a real-gas equation of state is more reliable.