Air Density and Specific Weight Equations and Calculator

Engineering Calculators
Engineering Physics

Air Density and Specific Weight Table, Equations and Calculator:

The density of air, ρ (Greek: rho) (air density), is the mass per unit volume of Earth's atmosphere. Air density, like air pressure, decreases with increasing altitude. It also changes with variation in temperature or humidity. At sea level and at 15 °C, air has a density of approximately 1.225 kg/m3 (0.001225 g/cm3, 0.0023769 slug/ft3, 0.0765 lbm/ft3) according to ISA (International Standard Atmosphere).

 Temperature F = Relative Humidity % RH = Barometer B (in) = Altitude (ft Above Sea Level) A = Equation Altitude (meters) = A*12*2.54/100 Temperature Degrees C = ((F-32)*5/9) Temperature kelvin k = C+273 Barometer  (mbar) = B/(29.92/1013) Barometer (mb) = 1013*EXP(-B7/7000) Barometer (in) = mb*(29.92/1013) Ms (g/kg) = 3.884266*10^((7.5*k)/(237.7+C)) M (g/kg) = Ms*RH/100 Tvc = ((1+1.609*M)/(1+M))*k Es (saturation pressure mb) = 6.11*10^(7.5*C/(237.7+k)) E (Vapor Ressure mb) = (RH*Es)/100 Tdc = (-430.22+237.7*LN(B17))/(-LN(B17)+19.08) Tdf = Tdc*9/5+32 Equation: D=P/(T*R) = Std Density (100) Temp, Altitude, Pressure, and Humidity Barometer (alt-station) as = mb*EXP(-B7/7000) D (air density) (kg/m3) ad = (as*100)/(B9*287) Corrected Density = D (virt air density) (kg/m3) vad = (as*100)/((B15+273)*287) Corrected Density =

Specific weight and density of air at standard atmospheric pressure - Imperial Units:

 Temperature °F Density slugs/ft3 Specific Weight lb/ft3 -40 .002939 .09456 -20 .002805 .09026 0 .002683 .08633 10 .002626 .08449 20 .002571 .08273 30 .002519 .08104 40 .002469 .07942 50 .002420 .07786 60 .002373 .07636 70 .002329 .07492 80 .002286 .07353 90 .002244 .07219 100 .002204 .07090 120 .002128 .06846 140 .002057 .06617 160 .001990 .06404 180 .001928 .06204 200 .001870 .06016 250 .001756 .05598 300 .001624 .05224 400 .001435 .04616 500 .001285 .04135 750 .001020 .03280 1,000 .000845 .02717 1,500 .000629 .02024

Specific weight and density of air at standard atmospheric pressure - SI Units:

 Temperature °C Density kg/m3 Specific Weight N/m3 -40 1.514 14.85 -20 1.395 13.68 0 1.293 12.67 5 1.269 12.45 10 1.247 12.23 15 1.225 12.01 20 1.204 11.81 25 1.184 11.61 30 1.165 11.43 40 1.127 11.05 50 1.109 10.88 60 1.060 10.40 70 1.029 10.09 80 0.9996 9.803 90 0.9721 9.533 100 0.9461 9.278 200 0.7461 7.317 300 0.6159 6.040 400 0.5243 5.142 500 0.4565 4.477 1000 0.2772 2.719