What Is a PV=nRT Calculator?
A PV=nRT calculator solves the ideal gas law for any one of its variables — pressure (P), volume (V), number of moles (n), or temperature (T) — given the other three. The ideal gas law is a cornerstone of chemistry and physics, describing the behavior of gases under many conditions. Enter the values you know and the calculator solves for the unknown using the gas constant R.
How to Use the Calculator
- Choose the variable to solve for — P, V, n, or T.
- Enter the three known values with their units.
- Calculate — see the unknown value.
The Ideal Gas Law
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). The value of R depends on your units — for example, 0.08206 L·atm/(mol·K) or 8.314 J/(mol·K).
Rearranged Forms
| Solve For | Formula |
|---|---|
| Pressure | P = nRT ÷ V |
| Volume | V = nRT ÷ P |
| Moles | n = PV ÷ (RT) |
| Temperature | T = PV ÷ (nR) |
Important Units
- Temperature must be in Kelvin — add 273.15 to Celsius.
- Match R to your units — use 0.08206 L·atm/(mol·K) with atmospheres and liters.
- Volume and pressure should be consistent with the chosen R.
When the Ideal Gas Law Applies
The ideal gas law works well for many gases at moderate temperatures and low to moderate pressures. At very high pressures or very low temperatures, real gases deviate from ideal behavior, and more complex equations (like the van der Waals equation) may be needed.
Frequently Asked Questions
What is the ideal gas law?
It is PV = nRT, relating pressure, volume, moles, and temperature of a gas through the gas constant R. You can solve it for any one variable given the others.
What units does temperature need to be in?
Temperature must be in Kelvin. Convert from Celsius by adding 273.15.
What is the value of R?
The gas constant R is 0.08206 L·atm/(mol·K) when using atmospheres and liters, or 8.314 J/(mol·K) in SI units. Choose the value that matches your units.
How do I solve for moles?
Rearrange to n = PV ÷ (RT). Enter pressure, volume, and temperature, and the calculator divides by R times temperature to find the number of moles.
Is this PV=nRT calculator free?
Yes — it is completely free, requires no signup, and solves for any variable.