How to use the Ideal Gas Law Calculator
Choose the unknown in Solve for, enter the other three values, and select their units. After you select Calculate, the result includes the selected quantity, Formula & steps, and text controls for Copy result and Download result (.txt).
- Choose Pressure (P), Volume (V), Amount of gas (n), or Temperature (T) in Solve for.
- Enter the other three values in their labeled fields.
- Choose a value in Pressure unit, Volume unit, Amount unit, or Temperature unit.
- Select Calculate, then read Formula & steps or select Copy result or Download result (.txt).
Calculate pressure with PV = nRT
Leave Pressure (P) selected in Solve for. Enter Volume (V), Amount of gas (n), and Temperature (T), then select Calculate. The calculator converts the known values to liters, moles, and Kelvin before applying the equation.
n = 1 mol, T = 273.15 K, V = 22.4 L
P = nRT / V = (1 x 0.0820573660809596 x 273.15) / 22.4
P = 1.00062 atmFormula & steps show the rounded gas constant as 0.0821, the normalized known values, and the pressure calculation. The result uses the selected Pressure unit.
Which units the Ideal Gas Law Calculator accepts
Pressure unit includes Atmospheres (atm), Kilopascals (kPa), Pascals (Pa), Millimeters of mercury (mmHg), Pounds per square inch (psi), and Bar. Volume unit includes Liters (L), Milliliters (mL), Cubic meters (m³), and Cubic feet (ft³). Amount unit includes Moles (mol) and Millimoles (mmol). Temperature unit includes Kelvin (K), Celsius (°C), and Fahrenheit (°F).
The calculation converts pressure, volume, amount of gas, and temperature to atm, L, mol, and K. It converts the answer to the selected unit for the quantity being solved. The form has no gauge-pressure option, so Pressure (P) is treated as an absolute value.
Why the Ideal Gas Law Calculator rejects an input
Pressure, volume, and amount of gas must be finite numbers greater than zero. Temperature can be below 0 on the Celsius or Fahrenheit scale, but its converted value must be above 0 K. Empty fields, plus signs, exponent notation, and a trailing decimal such as 1. fail the numeric check. Each entered value also has an absolute limit of 1e12.
Select Reset to clear the fields, restore the default units, return Solve for to Pressure (P), and hide the result.
What the calculation leaves out
The result comes from PV = nRT and the entered values. The calculator does not adjust for real-gas behavior, identify a specific gas, or infer a second missing quantity.
Copy result places the displayed result text in the clipboard when copying succeeds. Download result (.txt) creates a text file containing the result and steps.
Choose another science calculator
Browse Science Calculators for Physics, Chemistry and More when the unknown is outside pressure, volume, amount of gas, and temperature. Choose the Pressure Calculator for pressure from force and area. Choose the Density Calculator for density, mass, and volume. The Chemistry Calculator covers pH, dilution, molar mass, stoichiometry, and other listed chemistry calculations.
Frequently asked questions
What does the Ideal Gas Law Calculator solve for?
Select Pressure (P), Volume (V), Amount of gas (n), or Temperature (T) in Solve for, then enter the other three values.
How do I calculate pressure using PV = nRT?
Choose Pressure (P) in Solve for, enter Volume (V), Amount of gas (n), and Temperature (T), then select Calculate. The calculator converts the known values and applies P = nRT / V.
What units can I enter in the ideal gas law calculator?
Choose units in Pressure unit, Volume unit, Amount unit, and Temperature unit. The calculation converts the inputs to atm, L, mol, and K before solving.
Why is my temperature rejected by the calculator?
Temperature is rejected when its converted value is 0 K or below. Celsius and Fahrenheit values are converted before this check.
Does this ideal gas calculator account for real gas behavior?
The calculator applies the ideal-gas relationship only. It does not model or correct for real-gas behavior.