PV = nRT Calculator
Use this pv nrt calculator to solve for pressure, volume, moles, or temperature in the ideal gas law equation: PV = nRT.
Using liters and atmospheres by default.
Keep your units consistent with your chosen value of R.
If you are looking for a simple, reliable pv nrt calculator, this page is designed for exactly that. The Ideal Gas Law is one of the most useful equations in chemistry, physics, and engineering because it lets you estimate the behavior of gases under many everyday and lab conditions.
What does PV = nRT mean?
The equation PV = nRT links four core gas properties:
- P = pressure
- V = volume
- n = amount of gas in moles
- T = absolute temperature in kelvin
- R = ideal gas constant (depends on chosen units)
If you know three variables and R, you can solve for the fourth. That is exactly what the calculator above does.
How to use this pv nrt calculator
Step 1: Choose what you want to solve for
Select pressure, volume, moles, or temperature from the “Solve for” dropdown. The selected variable is auto-disabled because it will be calculated.
Step 2: Choose a unit preset
Use one of the presets to automatically fill the most common R value:
- atm + L: R = 0.082057 L·atm/(mol·K)
- Pa + m³: R = 8.314462618 J/(mol·K)
- kPa + L: R = 8.314462618 kPa·L/(mol·K)
You can also choose custom mode and provide your own gas constant.
Step 3: Enter your known values
Input the three known variables and verify that temperature is in kelvin. Enter positive numbers only.
Step 4: Click Calculate
The result appears instantly with the formula used, making it easy to verify your work.
Common formula rearrangements
- Pressure: P = (nRT) / V
- Volume: V = (nRT) / P
- Moles: n = (PV) / (RT)
- Temperature: T = (PV) / (nR)
These are algebraic rearrangements of the same law. The calculator performs these automatically to avoid arithmetic mistakes.
Worked examples
Example 1: Find pressure
Suppose n = 0.5 mol, T = 300 K, V = 10 L, and R = 0.082057. Then:
P = nRT/V = (0.5 × 0.082057 × 300) / 10 = 1.230855 atm
Example 2: Find moles
If P = 2 atm, V = 5 L, T = 350 K, and R = 0.082057:
n = PV/RT = (2 × 5) / (0.082057 × 350) ≈ 0.348 mol
Example 3: Find temperature
Given P = 101325 Pa, V = 0.020 m³, n = 0.8 mol, and R = 8.314462618:
T = PV/(nR) = (101325 × 0.020)/(0.8 × 8.314462618) ≈ 304.7 K
Frequent mistakes to avoid
- Using °C instead of K: convert with K = °C + 273.15.
- Mixing incompatible units: pressure, volume, and R must match.
- Using zero or negative values: these are non-physical for most ideal gas calculations.
- Rounding too early: keep extra decimals until final output.
When the ideal gas law is less accurate
The ideal gas model works best at relatively low pressure and high temperature, where molecules interact less. At very high pressures or near condensation, real gases deviate from ideal behavior and equations like Van der Waals may be more accurate.
Why this calculator is useful
A good pv nrt calculator saves time in:
- Chemistry homework and exam preparation
- General physics and thermodynamics practice
- Intro engineering calculations
- Lab estimates and sanity checks
Use it as a fast check, then show full units and setup in formal coursework.
Quick FAQ
Do I always need R?
Yes. If units are consistent and unchanged across a ratio problem, R may cancel in manual derivations, but this calculator still uses an explicit R value.
Can I use this for gas mixtures?
Yes for total gas behavior if you use total pressure and total moles under ideal assumptions.
What if I get a strange result?
Double-check unit consistency, especially pressure units and temperature in kelvin. Those two cause most errors.