Ideal Gas Law Calculator
Calculate pressure, volume, moles, temperature using PV = nRT
About the Ideal Gas Law Calculator
The Ideal Gas Law (PV = nRT) relates pressure, volume, amount of gas in moles, and temperature for an ideal gas. The Ideal Gas Law Calculator solves for any of these four variables when you know the other three, supporting multiple unit systems for pressure (atm, kPa, mmHg, torr, bar), volume (L, mL, m³), and temperature (K, °C, °F).
Students solve gas law homework problems, chemists calculate gas quantities for reactions, and engineers analyze gas behavior in industrial processes. The calculator automatically uses the correct gas constant R value based on your chosen units, eliminating a common source of calculation errors.
Because calculations run entirely in your browser using JavaScript, you can solve gas law problems without any data leaving your device. The tool explains when real gases deviate from ideal behavior in the FAQ section.
How to Use the Ideal Gas Law Calculator
- Select what you want to calculate from the dropdown: pressure, volume, moles, or temperature.
- Enter the three known values in their respective input fields.
- Set the pressure, volume, and temperature units so the matching gas constant is applied.
- Click Calculate to solve for the unknown variable using PV = nRT.
- Read the answer, which is presented across several equivalent units.
Why Use ToolForge’s Ideal Gas Law Calculator
- Ideal gas law calculations run entirely in your browser—no server communication occurs, ensuring your chemistry calculations remain private and the tool works offline.
- Solves for any of the four variables (pressure, volume, moles, temperature) when you know the other three, making it versatile for different problem types.
- Automatically selects the correct gas constant R value based on your chosen units, eliminating a common source of calculation errors.
- Handles unit conversions between different pressure (atm, kPa, mmHg, torr, bar), volume (L, mL, m³), and temperature (K, °C, °F) systems automatically.
Frequently Asked Questions
What is the ideal gas law?
The ideal gas law is PV = nRT, where P is pressure, V is volume, n is the number of moles of gas, R is the gas constant, and T is temperature in Kelvin. It relates the four state variables of an ideal gas and is a good approximation for many real gases under standard conditions.
What pressure, volume, and temperature units does it accept?
The calculator supports atmospheres, kilopascals, mmHg, torr, and bar for pressure; liters, milliliters, and cubic meters for volume; and Kelvin, Celsius, and Fahrenheit for temperature. The gas constant R is automatically selected based on your units.
What is the gas constant R?
The gas constant R has different values depending on the units used. Common values include 0.0821 L·atm/(mol·K), 8.314 J/(mol·K), 62.36 L·mmHg/(mol·K), and 8.314 kPa·L/(mol·K). The calculator automatically uses the correct value for your chosen units.
When does the ideal gas law apply?
The ideal gas law applies to ideal gases under standard conditions. Real gases deviate from ideal behavior at high pressures and low temperatures when intermolecular forces become significant. However, the law is a good approximation for many situations at moderate conditions.
Why must temperature be in Kelvin?
The ideal gas law requires absolute temperature because gas volume is directly proportional to absolute temperature. Celsius and Fahrenheit can be used for input, but the calculator converts them to Kelvin for the calculation to ensure accuracy.
