ρ = density, units typically [kg/m 3 ] or [lb/ft 3 ]
m = mass, units typically [kg] or [lb]
V = volume, units typically [m 3 ] or [ft 3 ]
Specific weight is the ratio of the weight to the volume of a substance:
γ = (m * g)/V = ρ * g [2]
where
γ = specific weight, units typically [N/m 3 ] or [lb f /ft 3 ]
m = mass, units typically [g] or [lb]
g = acceleration due to gravity, units typically [m/s 2 ] and value on Earth usually given as 9.80665 m/s 2 or 32.17405 ft/s 2
V = volume, units typically [cm 3 ] or [ft 3 ]
ρ = density, units typically [g/cm 3 ] or [lb/ft 3 ]
Tabulated values and density units conversion are given below the figures . At the bottom of the page there are some examples of calculations using hot and cold air.
See also Air Composition and molecular weight , Density at varying pressure , Diffusion Coefficients for Gases in Air , Dynamic (absolute) and kinematic viscosity , Prandtl Number , Specific heat at varying temperature and Specific heat at varying pressure , Thermal Conductivity , Thermal Diffusivity , Properties at gas-liquid equilibrium conditions and Air thermophysical properties , for other properties of air .
For other substances, see Density and specific weight o acetone , ammonia , argon , benzene , butane , carbon dioxide , carbon monoxide , ethane , ethanol , ethylene , helium , hydrogen , methane , methanol , nitrogen , oxygen , pentane , propane , toluene and water , as well as Density of crude oil , Density of fuel oils , Density of lubricating oil and Density of jet fuel as function of temperature.
The calculator below can be used to calculate the air density and specific weight at given temperatures and atmospheric pressure.
The output density is given as kg/m 3 , lb/ft 3 , lb/gal(US liq) and sl/ft 3 . Specific weight is given as N/m 3 and lb f / ft 3 .
Note! Temperature must be within the ranges -100 - 1600 °C, -140 - 2900 °F, 175 - 1900 K and 315 - 3400 °R to get valid values.
Choose the actual unit of temperature:
Air density and specific weight at atmospheric pressure:
Air density at ambient temperature and pressure:
Air density at varying pressure and temperature:
Air density at gas-liquid equilibrium pressure:
Air thermal expansion coefficient at atmospheric pressure:
Density, specific weight and thermal expansion coefficient of air at 1 atmosphere pressure, at temperatures given as °F:
For full table specific weight and thermal expansion coefficient - rotate the screen!
Temperature | Density | Specific weight | Thermal expansion coefficient | ||||
[°F] | [lb m /ft 3 ] | [sl/ft 3 *10 -3 ] | [lb m /gal(US liq)] | [kg/m 3 ] | [lb f /ft 3 ] | [N/m 3 ] | [x10 -3 °F -1 ] |
-100 | 0.1104 | 3.431 | 0.01476 | 1.768 | 0.1104 | 17.34 | 2.83 |
-50 | 0.0968 | 3.010 | 0.01295 | 1.551 | 0.0968 | 15.21 | 2.48 |
-20 | 0.0902 | 2.803 | 0.01206 | 1.445 | 0.0902 | 14.17 | 2.30 |
0 | 0.0862 | 2.681 | 0.01153 | 1.382 | 0.0862 | 13.55 | 2.20 |
10 | 0.0844 | 2.624 | 0.01128 | 1.352 | 0.0844 | 13.26 | 2.15 |
20 | 0.0826 | 2.569 | 0.01105 | 1.324 | 0.0826 | 12.98 | 2.10 |
30 | 0.0810 | 2.516 | 0.01082 | 1.297 | 0.0810 | 12.72 | 2.06 |
40 | 0.0793 | 2.466 | 0.01061 | 1.271 | 0.0793 | 12.46 | 2.02 |
50 | 0.0778 | 2.418 | 0.01040 | 1.246 | 0.0778 | 12.22 | 1.98 |
60 | 0.0763 | 2.372 | 0.01020 | 1.222 | 0.0763 | 11.99 | 1.94 |
70 | 0.0749 | 2.327 | 0.01001 | 1.199 | 0.0749 | 11.76 | 1.90 |
80 | 0.0735 | 2.284 | 0.00982 | 1.177 | 0.0735 | 11.55 | 1.87 |
100 | 0.0709 | 2.203 | 0.00948 | 1.135 | 0.0709 | 11.14 | 1.80 |
120 | 0.0685 | 2.128 | 0.00915 | 1.097 | 0.0685 | 10.75 | 1.74 |
140 | 0.0662 | 2.057 | 0.00885 | 1.060 | 0.0662 | 10.40 | 1.68 |
160 | 0.0641 | 1.991 | 0.00856 | 1.026 | 0.0641 | 10.06 | 1.63 |
180 | 0.0621 | 1.929 | 0.00830 | 0.994 | 0.0621 | 9.75 | 1.58 |
200 | 0.0602 | 1.870 | 0.00804 | 0.964 | 0.060 | 9.45 | 1.53 |
250 | 0.0559 | 1.738 | 0.00747 | 0.896 | 0.0559 | 8.78 | 1.41 |
300 | 0.0522 | 1.622 | 0.00698 | 0.836 | 0.0522 | 8.20 | 1.30 |
350 | 0.0489 | 1.521 | 0.00654 | 0.784 | 0.0489 | 7.69 | 1.23 |
400 | 0.0461 | 1.432 | 0.00616 | 0.738 | 0.0461 | 7.24 | 1.16 |
450 | 0.0436 | 1.354 | 0.00582 | 0.698 | 0.0436 | 6.84 | 1.10 |
500 | 0.0410 | 1.274 | 0.00548 | 0.656 | 0.0410 | 6.43 | 1.05 |
600 | 0.0371 | 1.152 | 0.00496 | 0.599 | 0.0371 | 5.82 | 0.96 |
700 | 0.0340 | 1.057 | 0.00455 | 0.545 | 0.0340 | 5.35 | 0.88 |
800 | 0.0315 | 0.978 | 0.00421 | 0.5042 | 0.0315 | 4.94 | 0.81 |
1000 | 0.0272 | 0.845 | 0.00363 | 0.4354 | 0.0272 | 4.27 | 0.70 |
1200 | 0.0239 | 0.743 | 0.00319 | 0.3827 | 0.0239 | 3.75 | 0.61 |
1400 | 0.0213 | 0.663 | 0.00285 | 0.3416 | 0.0213 | 3.35 | 0.54 |
1600 | 0.0193 | 0.599 | 0.00257 | 0.3085 | 0.0193 | 3.03 | 0.49 |
1800 | 0.0176 | 0.546 | 0.00235 | 0.2813 | 0.0176 | 2.76 | 0.45 |
2000 | 0.0161 | 0.501 | 0.00216 | 0.2583 | 0.0161 | 2.53 | 0.42 |
Density and specific weight of air at 1 atmosphere pressure, at temperatures given as °C:
For full table specific weight and thermal expansion coefficient - rotate the screen!
Temperature | Density | Specific weight | Thermal expansion coefficient | ||||
[°C] | [kg/m 3 ] | [lb m /ft 3 ] | [sl/ft 3 *10 -3 ] | [lb m /gal(US liq)] | [N/m 3 ] | [lb f /ft 3 ] | [x10 -3 K -1 ] |
-75 | 1.783 | 0.1113 | 3.460 | 0.01488 | 17.49 | 0.11131 | 5.14 |
-50 | 1.582 | 0.0988 | 3.070 | 0.01320 | 15.52 | 0.09878 | 4.55 |
-25 | 1.422 | 0.0888 | 2.759 | 0.01187 | 13.94 | 0.08877 | 4.08 |
-15 | 1.367 | 0.0853 | 2.652 | 0.01141 | 13.40 | 0.08532 | 3.92 |
-10 | 1.341 | 0.0837 | 2.601 | 0.01119 | 13.15 | 0.08370 | 3.84 |
-5 | 1.316 | 0.0821 | 2.553 | 0.01098 | 12.90 | 0.08214 | 3.76 |
0 | 1.292 | 0.0806 | 2.506 | 0.01078 | 12.67 | 0.08063 | 3.69 |
5 | 1.268 | 0.0792 | 2.461 | 0.01059 | 12.44 | 0.07919 | 3.62 |
10 | 1.246 | 0.0778 | 2.418 | 0.01040 | 12.22 | 0.07780 | 3.56 |
15 | 1.225 | 0.0765 | 2.376 | 0.01022 | 12.01 | 0.07645 | 3.50 |
20 | 1.204 | 0.0752 | 2.336 | 0.01005 | 11.81 | 0.07516 | 3.43 |
25 | 1.184 | 0.0739 | 2.297 | 0.00988 | 11.61 | 0.07390 | 3.38 |
30 | 1.164 | 0.0727 | 2.259 | 0.00972 | 11.42 | 0.07269 | 3.32 |
40 | 1.127 | 0.0704 | 2.188 | 0.00941 | 11.06 | 0.07039 | 3.21 |
50 | 1.093 | 0.0682 | 2.120 | 0.00912 | 10.72 | 0.06822 | 3.12 |
60 | 1.060 | 0.0662 | 2.057 | 0.00885 | 10.40 | 0.06619 | 3.02 |
80 | 1.000 | 0.0625 | 1.941 | 0.00835 | 9.81 | 0.06245 | 2.85 |
100 | 0.9467 | 0.0591 | 1.837 | 0.00790 | 9.28 | 0.05910 | 2.70 |
125 | 0.8868 | 0.0554 | 1.721 | 0.00740 | 8.70 | 0.05536 | 2.51 |
150 | 0.8338 | 0.0521 | 1.618 | 0.00696 | 8.18 | 0.05206 | 2.33 |
175 | 0.7868 | 0.0491 | 1.527 | 0.00657 | 7.72 | 0.04912 | 2.22 |
200 | 0.7451 | 0.0465 | 1.446 | 0.00622 | 7.31 | 0.04651 | 2.10 |
225 | 0.7078 | 0.0442 | 1.373 | 0.00591 | 6.94 | 0.04419 | 2.01 |
300 | 0.6168 | 0.0385 | 1.197 | 0.00515 | 6.05 | 0.03850 | 1.76 |
400 | 0.5238 | 0.0327 | 1.016 | 0.00437 | 5.14 | 0.03270 | 1.52 |
500 | 0.4567 | 0.0285 | 0.886 | 0.00381 | 4.48 | 0.02851 | 1.32 |
600 | 0.4043 | 0.0252 | 0.784 | 0.00337 | 3.96 | 0.02524 | 1.16 |
700 | 0.3626 | 0.0226 | 0.704 | 0.00303 | 3.56 | 0.02264 | 1.03 |
800 | 0.3289 | 0.0205 | 0.638 | 0.00274 | 3.23 | 0.02053 | 0.94 |
900 | 0.3009 | 0.0188 | 0.584 | 0.00251 | 2.95 | 0.01879 | 0.86 |
1000 | 0.2773 | 0.0173 | 0.538 | 0.00231 | 2.72 | 0.01731 | 0.80 |
1100 | 0.2571 | 0.0160 | 0.499 | 0.00215 | 2.52 | 0.01605 | 0.75 |
kilogram/cubic meter [kg/m 3 ] = gram/liter [g/l], kilogram/liter [kg/l] = gram/cubic centimeter [g/cm 3 ]= ton(metric)/cubic meter [t/m 3 ], once/gallon(US liquid) [oz/gal(US liq)] pound/cubic inch [lb/in 3 ], pound/cubic foot [lb/ft 3 ], pound/gallon(UK) [lb/gal(UK)], pound/gallon(US liquid) [lb/gal(US liq)], slug/cubic foot [sl/ft 3 ], ton(short)/cubic yard [ton(short)/yd 3 ], ton(long)/cubic yard [yd 3 ]
Example - Mass of Air at Temperature 100 o C
From the table above - the density of air is 0.946 kg/m 3 at 100 o C. The mass of 10 m 3 air can be calculated as
m = V ρ
= 10 [m 3 ] * 0.946 [kg/m 3 ] = 9.46 [kg]
where
m = mass [kg]
V = volume [m 3 ]
ρ = density [kg/m 3 ]
Example - Mass of Air at Temperature 20 o C
From the table above - the density of air is 1.205 kg/m 3 at 20 o C. The mass of 10 m 3 air can be calculated as
m = 10 [m 3 ] * 1.205 [kg/m 3 ] = 12.05 [kg]
Example - Lifting Force of a Hot Air Balloon
An air balloon with volume 10 m 3 is heated to 100 o C. The temperature of the surrounding air is 20 o C. The change in gravity force (weight) of the air volume is the potential lifting force of the balloon. The lifting force can be calculated as
F l = dm a g = V dρ a g
= 10 [m 3 ] *(1.205 - 0.946) [kg/m 3 ]*9.81 [m/s 2 ] = 25.4 [N]
where
F l = lifting force - change in gravity force (weight) [N]
a g = acceleration of gravity (9.81 [m/s 2 ])
dm = V dρ = change of mass in the balloon [kg]
dρ = change in density due to temperature difference [kg/m 3 ]
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