# Density of Air at Different Temperatures

The density of air is affected by several factors, mainly temperature, pressure, and humidity. At normal atmospheric conditions (20°C and 1 atmospheric pressure), the density of dry air is approximately 1.204 kg/m^{3}.

The following charts and table provide comprehensive data on the density of dry air at different temperatures, taken under 1 atmospheric (atm) pressure. (1 atm = 101,325 Pa)

Click on the icon to switch between SI (kg/m^{3}) and US customary/Imperial (lb/ft^{3}) units.

Temperature °C | Density (kg/m ^{3}) |
---|---|

-25 | 1.422 |

-20 | 1.394 |

-15 | 1.367 |

-10 | 1.341 |

-5 | 1.316 |

0 | 1.292 |

5 | 1.268 |

10 | 1.246 |

15 | 1.225 |

20 | 1.204 |

25 | 1.184 |

30 | 1.164 |

35 | 1.146 |

40 | 1.127 |

50 | 1.093 |

60 | 1.060 |

80 | 1.000 |

100 | 0.9467 |

125 | 0.8868 |

150 | 0.8338 |

175 | 0.7868 |

200 | 0.7451 |

225 | 0.7078 |

300 | 0.6168 |

400 | 0.5238 |

500 | 0.4567 |

600 | 0.4043 |

700 | 0.3626 |

800 | 0.3289 |

900 | 0.3009 |

1000 | 0.2773 |

## How to Calculate the Density of Air

To calculate the density of air, We need to calculate the partial pressure of the dry air and the partial pressure of the water vapor.

Step 1) We calculate the saturation vapor pressure (vapor pressure at 100% relative humidity).

There are several algorithims used for calculating the vapor pressure. In our calculator we use a polynomial developed by Herman Wobus, which gives a very reasonable precesion.

E_{s} = E_{so} / p^{8}

Where:

- E
_{s}is the saturation pressure of water vapor (hPa) - e
_{so}= 6.1078 - p = c
_{0}+ T (c_{1}+ T (c_{2}+ T (c_{3}+ T (c_{4}+ T (c_{5}+ T (c_{6}+ T (c_{7}+ T (c_{8}+ T (c9)))))))) - T is the air temperature in degrees Celsius
- c
_{0}= 0.99999683 - c
_{1}= -0.90826951 × 10^{-2} - c
_{2}= 0.78736169 × 10^{-4} - c
_{3}= -0.61117958 × 10^{-6} - c
_{4}= 0.43884187 × 10^{-8} - c
_{5}= -0.29883885 × 10^{-10} - c
_{6}= 0.21874425 × 10^{-12} - c
_{7}= -0.17892321 × 10^{-14} - c
_{8}= 0.11112018 × 10^{-16} - c
_{9}= -0.30994571 × 10^{-19}

Step 2) Find the actual vapor pressure, by multiplying the saturation vapor pressure times the relative humidity:

p_{v} = E_{s} × Relative humidity

Step 3) Calculate the pressure of dry air p_{d}, by subtracting the vapor pressure from the total air pressure:

p_{d} = p_{total} - p_{v}

Step 4) Now, you can find the air density by plugin the values in the following equation:

Where:

- ρ
_{air}is the density of air in kg/m^{3} - p
_{d}is the partial pressure of dry air in Pascals (Pa) - p
_{v}is the pressure of water vapor in Pascals (Pa) - T is the temperature in Kelvins (K)
- R
_{d}is the specific gas constant for dry air = 287.058 J/(kg·K) - R
_{v}is the specific gas constant for water vapour = 461.495 J/(kg·K)

**References:**1) CRC Handbook of Chemistry and Physics, 97th Edition. United Kingdom: CRC Press, 2016-2017. 2) Cardarelli, François. Materials Handbook: A Concise Desktop Reference. Switzerland: Springer International Publishing, 2018. 3) Wikipedia. “Density of air.”