TFT

Moles to Volume Calculator for Gas – STP and Custom Conditions

Convert moles of gas to liters at STP or any temperature and pressure with our moles-to-volume gas calculator. Uses the ideal gas law for accurate results. Great for chemistry students and lab professionals.

Understanding Gas Volume Calculations

The ideal gas law relates moles, volume, temperature, and pressure of a gas. At STP (Standard Temperature and Pressure), 1 mole of any ideal gas occupies 22.4 liters.

Ideal Gas Law

PV = nRT

Where:

  • P = Pressure (atm)
  • V = Volume (L)
  • n = Number of moles (mol)
  • R = Gas constant (0.08206 L·atm/(mol·K))
  • T = Temperature (K)

STP Conditions

StandardTemperaturePressureMolar Volume
STP (old)0°C (273.15 K)1 atm22.4 L/mol
STP (IUPAC)0°C (273.15 K)1 bar22.7 L/mol
SATP25°C (298.15 K)1 bar24.8 L/mol

Example Calculation

Calculate the volume of 2 moles of gas at 25°C and 1 atm:

V = nRT/P = (2 mol × 0.08206 × 298.15 K) / 1 atm = 48.9 L

Moles-Volume Comparison

Enter values and calculate to see the chart

Quick Reference: Molar Volumes
MolesVolume at STPVolume at 25°C
0.1 mol2.24 L2.45 L
0.5 mol11.2 L12.2 L
1 mol22.4 L24.5 L
2 mol44.8 L48.9 L
5 mol112 L122 L
How to Use This Calculator
1

Choose conversion direction

Select "Moles to Volume" or "Volume to Moles" from the dropdown.

2

Enter values and conditions

Input moles or volume, plus temperature and pressure. Select your units.

3

Calculate

The calculator uses the ideal gas law to find the unknown value.

Frequently Asked Questions

Why is 1 mole of gas 22.4 L at STP?
Plug STP values into PV = nRT: V = nRT/P = (1 mol)(0.08206)(273.15 K)/(1 atm) = 22.4 L. This is why the number appears so often in gas calculations.
When does the ideal gas law fail?
At high pressures (molecules are close together) and low temperatures (molecules move slowly), real gases deviate from ideal behavior. Use van der Waals equation for more accuracy.
How do I convert Celsius to Kelvin?
Add 273.15. 0°C = 273.15 K, 25°C = 298.15 K, 100°C = 373.15 K. The gas law requires absolute temperature (Kelvin) because 0 K is true zero energy.
Does the type of gas matter?
For ideal gases, no. One mole of any ideal gas occupies the same volume at the same T and P. Real gases differ slightly, but the ideal gas law treats all gases identically.
What's the difference between STP and SATP?
STP (Standard Temperature and Pressure) is 0°C and 1 atm or 1 bar. SATP (Standard Ambient Temperature and Pressure) is 25°C and 1 bar—closer to lab conditions.

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