Ideal gas equation calculator

Worked example

Find p, the pressure. Given: volume V = 0.0224 m³; amount of gas n = 1.00 mol; temperature T = 273 K; molar gas constant R = 8.31 J/(mol K).

1. Write the equation
   p V = n R T
2. Rearrange to make p the subject
   p = n R T / V
3. Constants used
   R = 8.31 J/(mol K)
4. Substitute the values
   p = 1 × 8.31 × 273 ÷ 0.0224
5. Calculate
   p = 1.01278 × 10⁵ Pa
6. Give the answer to 3 significant figures
   p = 1.01 × 10⁵ Pa

Symbols and units

Ideal gas equation: rearranged

• To find pressure: p = n R T / V
• To find volume: V = n R T / p
• To find amount of gas: n = p V / (R T)
• To find temperature: T = p V / (n R)

Exam tip

Temperature must be in kelvin. Add 273 to a temperature in °C. The unit selector converts for you.

Common questions

What is the formula for ideal gas equation?

The equation is p V = n R T, where p is the pressure (Pa); V is the volume (m³); n is the amount of gas (mol); T is the temperature (K); R is the molar gas constant (J/(mol K)).

What units should I use for ideal gas equation?

In SI units: pressure in Pa, volume in m³, amount of gas in mol, molar gas constant in J/(mol K), temperature in K. The calculator also accepts common alternatives such as kilometres, grams or minutes, and converts them for you.

How do I rearrange p V = n R T?

Rearranging gives these forms: to find pressure: p = n R T / V. to find volume: V = n R T / p. to find amount of gas: n = p V / (R T). to find temperature: T = p V / (n R).