Gas Density Stp
Calculator
Results
- Density (g/L)
- 1.963463
- Molar volume at STP (L/mol)
- 22.413969
- Density (kg/m³)
- 1.963463
Chemistry results
| Density (g/L) | 1.963463 |
| Molar volume at STP (L/mol) | 22.413969 |
| Density (kg/m³) | 1.963463 |
formula-map diagram
- Density (g/L)
- 1.963463
- Molar volume at STP (L/mol)
- 22.413969
- Density (kg/m³)
- 1.963463
Formula breakdown
Formula
ρ = M ÷ Vm (Vm = 22.414 L/mol at 0 °C, 1 atm)= 1.9634630051413
Note
Simplified model: these results assume ideal behaviour (ideal gases, dilute solutions, complete reactions) and standard textbook constants. Real laboratory values vary with temperature, pressure, purity and activity coefficients. Do not rely on this for safety-critical or analytical work.
More in Chemistry
See all →Frequently asked questions
What is STP and why does it matter for gas density?+
STP (Standard Temperature and Pressure) is commonly defined as 0°C (273.15 K) and 1 atm pressure, a fixed reference point that lets gas properties like density be compared consistently across different gases and experiments. Gas density changes with temperature and pressure, so a reference condition is needed for meaningful comparisons.
How is gas density at STP calculated?+
Using the ideal gas law rearranged for density: density = (P x M) / (R x T), where M is the gas's molar mass, P is pressure, R is the gas constant, and T is temperature in kelvin. At STP this simplifies to roughly molar mass divided by 22.4 L/mol.
Why do lighter gases like helium have lower density than air?+
At the same temperature and pressure, equal volumes of any ideal gas contain the same number of moles (and therefore molecules), so density differences between gases come down entirely to differences in molar mass. Helium's molar mass (4 g/mol) is much lower than air's average (about 29 g/mol), making it far less dense.
What is molar volume and how does it relate to gas density at STP?+
Molar volume is the volume occupied by one mole of an ideal gas at a given temperature and pressure — approximately 22.4 L/mol at STP (0°C, 1 atm). Dividing a gas's molar mass by this molar volume gives its density directly.
Do real gases match the density predicted by the ideal gas law at STP?+
Most gases come close at STP, but gases that deviate from ideal behavior — due to intermolecular forces or molecular size — like ammonia or water vapor, show small but measurable differences from the ideal prediction. For most everyday chemistry problems, the ideal approximation is accurate enough.