When to use this calculator
Estimate ideal-gas density from absolute pressure, molar mass and temperature. Real gases can deviate significantly at high pressures or low temperatures.
Explore the gas laws calculators for other questions in this topic. For a related calculation, use the Gas Mole Fraction From Pressure Calculator: Recover ideal gas mole fraction from a component pressure and total pressure.
PUTTING IT INTO PRACTICE
Gas Density: a worked example
The values below are an illustrative example, not a recommendation. Replace them with measurements or assumptions that match your question.
| Input | Example value |
|---|---|
| Absolute pressure (Pa) | 101,325 |
| Molar mass (g/mol) | 28.97 |
| Temperature (K) | 298.15 |
| Result | 1.184121 kg/m³ |
- Check the input labels and enter the example values above.
- Apply the relationship: Density = pressure × molar mass(kg/mol) ÷ (RT).
- The result is 1.184121 kg/m³, rounded for display.
How to interpret your result
Real gases can deviate significantly at high pressures or low temperatures.
Gas-law ratios require absolute pressure and kelvin temperature. Hold the quantities specified by each law constant. Real gases can depart from ideal behaviour, especially at high pressure or low temperature.
Frequently asked questions
Can I enter Celsius in a gas-law temperature ratio?
No. Convert to absolute temperature in kelvins first. The Celsius zero point is not absolute zero.
How do I use the gas density calculator?
Enter absolute pressure (pa), molar mass (g/mol), temperature (k). The result updates automatically. Use the units shown beside each input; the example values illustrate the method.
Which formula does this calculator use?
Density = pressure × molar mass(kg/mol) ÷ (RT).
What should I check before using the result?
Real gases can deviate significantly at high pressures or low temperatures.
How are results rounded?
Scalar numbers display up to six decimal places, with scientific notation for very large or small values. Text, fraction, date and schedule outputs use the format described on the tool. Intermediate calculations use JavaScript floating-point arithmetic. Keep sensible precision for your measurements.
Further reading
For background on this topic, see OpenStax: gases and the ideal gas law ↗. This is a topic reference, not an external review or endorsement of this tool.
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