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Air - Specific Heat at Constant Pressure and Varying Temperature

Online calculator, figures and tables showing how specific heat (Cp and Cv) of dry air vary with temperature at different pressures, SI and imperial units

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Specific heat capacity (C) is the amount of heat required to change the temperature of a mass unit of a substance by one degree.

  • Isobaric heat capacity  (Cp) is used for air in a constant pressure (ΔP = 0) system.
  • Isochoric heat capacity  (Cv) is used for air in a constant-volume, (= isovolumetric or isometric) closed system.

Note! At normal atmospheric pressure of 1.013 bar - the specific heat of dry air - CP and CV - will vary with temperature. This may influence on the accuracy of air conditioning and industrial air handling process calculations. When calculating mass and volume flow of air in heated or cooled systems with high accuracy - the specific heat (= heat capacity) should be corrected according values in the figures and table below, or found by use of the calculator.

  • For ordinary calculations - a value of specific heat cp = 1.0 kJ/kg K (equal to kJ/kg oC) or 0.24 Btu(IT)/lb °F - is normally accurate enough
  • For higher accuracy - a value of Cp = 1.006 kJ/kg K (equal to kJ/kg oC) or 0.2403 Btu(IT)/lb °F  - is better

Online Air Heat Capacity Calculator

The calculator below can be used to estimate the air heat capacity at constant volum or constant pressure and at given temperature and pressure.
The output heat capacity is given as kJ/(kmol*K), kJ/(kg*K), kWh/(kg*K), kcal/(kg*K), Btu(IT)/(mol*°R) and Btu(IT)/(lbm*°R)

Temperature

Choose the actual unit of temperature: °C  °F  °R 
Choose the actual pressure:  1 bara / 14.5 psia; 10 bara / 145 psia; 50 bara / 725 psia; 100 bara / 1450 psia;

See also Air Composition and molecular weightDensity at varying pressure, Density and specific weight at varying temperature, Diffusion Coefficients for Gases in AirDynamic (absolute) and kinematic viscosity, Prandtl Number, Specific heat at varying temperature and Specific heat at varying pressureThermal ConductivityThermal Diffusivity, Properties at gas-liquid equilibrium conditions and Air properties, for other properties of air 


Air heat capacity Cp pressure temperature C

Air heat capacity Cp pressure temperature F
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Air heat capacity Cv pressure temperature C

Air heat capacity Cv pressure temperature F

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Air heat capacity equilibrium temperature C
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Heat capacity of air at 1 bar (=0.1 mPa = 14.5 psi):

Temperature Isochoric heat capacity, Cv Isobaric heat capacity, Cp Cp/Cv
[K] [°C] [°F] [kJ/mol K] [kJ/kg K] [kWh/(kg K)]

[kcal(IT)/(kg K)]
[Btu(IT)/lb °F]

[kcal(IT)/(lb °F)] [kJ/mol K] [kJ/kg K] [(kW h)/(kg K)] [kcal(IT)/(kg K)]
[Btu(IT)/lb °F]
[kcal(IT)/(lb °F)] [-]
60 -213 -352 0.03398 1.173 0.0003258 0.2802 0.2287 0.05506 1.901 0.000528 0.45405 0.37071 1.621
78.79 -194 -318 0.03044 1.051 0.0002919 0.2510 0.2050 0.05599 1.933 0.000537 0.46169 0.37695 1.839
81.61 -192 -313 0.02172 0.7500 0.0002083 0.1791 0.1463 0.03154 1.089 0.000303 0.26010 0.21237 1.452
100 -173 -280 0.02109 0.7280 0.0002022 0.1739 0.1420 0.03012 1.040 0.000289 0.24833 0.20276 1.428
120 -153 -244 1.02109 0.7211 0.0002003 0.1722 0.1406 1.03012 1.022 0.000284 0.24410 0.19930 1.009
140 -133 -208 0.02081 0.7184 0.0001996 0.1716 0.1401 0.02937 1.014 0.000282 0.24219 0.19774 1.411
160 -113 -172 0.02077 0.7172 0.0001992 0.1713 0.1399 0.02928 1.011 0.000281 0.24147 0.19716 1.410
180 -93.2 -136 0.02076 0.7166 0.0001991 0.1712 0.1397 0.02920 1.008 0.000280 0.24076 0.19657 1.407
200 -73.2 -99.7 0.02075 0.7163 0.0001990 0.1711 0.1397 0.02917 1.007 0.000280 0.24052 0.19638 1.406
220 -53.2 -63.7 0.02075 0.7163 0.0001990 0.1711 0.1397 0.02914 1.006 0.000279 0.24028 0.19618 1.404
240 -33.2 -27.7 0.02075 0.7164 0.0001990 0.1711 0.1397 0.02914 1.006 0.000279 0.24028 0.19618 1.404
260 -13.2 8.3 0.02076 0.7168 0.0001991 0.1712 0.1398 0.02914 1.006 0.000279 0.24028 0.19618 1.403
273.2 0.0 32.0 0.02077 0.7171 0.0001992 0.1713 0.1398 0.02914 1.006 0.000279 0.24028 0.19618 1.403
280 6.9 44.3 0.02078 0.7173 0.0001993 0.1713 0.1399 0.02914 1.006 0.000279 0.24028 0.19618 1.402
288.7 15.6 60.0 0.02078 0.7175 0.0001993 0.1714 0.1399 0.02914 1.006 0.000279 0.24030 0.19620 1.402
300 26.9 80.3 0.02080 0.7180 0.0001994 0.1715 0.1400 0.02915 1.006 0.000280 0.24036 0.19625 1.402
320 46.9 116 0.02083 0.7192 0.0001998 0.1718 0.1403 0.02917 1.007 0.000280 0.24052 0.19638 1.400
340 66.9 152 0.02087 0.7206 0.0002002 0.1721 0.1405 0.02923 1.009 0.000280 0.24100 0.19677 1.400
360 86.9 188 0.02092 0.7223 0.0002006 0.1725 0.1409 0.02926 1.010 0.000281 0.24123 0.19696 1.398
380 107 224 0.02098 0.7243 0.0002012 0.1730 0.1412 0.02931 1.012 0.000281 0.24171 0.19735 1.397
400 127 260 0.02105 0.7266 0.0002018 0.1735 0.1417 0.02937 1.014 0.000282 0.24219 0.19774 1.396
500 227 440 0.02150 0.7424 0.0002062 0.1773 0.1448 0.02983 1.030 0.000286 0.24597 0.20083 1.387
600 327 620 0.02213 0.7641 0.0002123 0.1825 0.1490 0.03044 1.051 0.000292 0.25103 0.20496 1.375
700 427 800 0.02282 0.7877 0.0002188 0.1881 0.1536 0.03114 1.075 0.000299 0.25675 0.20963 1.365
800 527 980 0.02351 0.8117 0.0002255 0.1939 0.1583 0.03183 1.099 0.000305 0.26249 0.21432 1.354
900 627 1160 0.02415 0.8338 0.0002316 0.1991 0.1626 0.03247 1.121 0.000311 0.26772 0.21858 1.344
1100 827 1520 0.02525 0.8716 0.0002421 0.2082 0.1700 0.03356 1.159 0.000322 0.27675 0.22596 1.329
1500 1227 2240 0.02673 0.9230 0.0002564 0.2204 0.1800 0.03505 1.210 0.000336 0.28901 0.23597 1.311
1900 1627 2960 0.02762 0.9535 0.0002649 0.2277 0.1859 0.03593 1.241 0.000345 0.29631 0.24193 1.301

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Unit conversion:

Specific heat unit converter

british thermal unit(International table) = [Btu(IT)], degree celcius = [°C], degree fahrenheit = [°F], degree kelvin = [K], degree rankin = [°R], joule = [J], kilocalorie(International table) = [kcal(IT)], kilogram = [kg], kilojoule = [kJ], kilowatthour = [kWh], mole = [mol], pound =[lb]

K in the units can be replaced by °C, and vise versa. °R in the units can be replaced by °F, and vise versa.

  • 1 Btu/(lb °F) = 1 Btu/(lb °R) = 1 kcal(IT)/(kg °C) = 1 kcal(IT)/(kg K) = 4186.8 J/(kg K) = 0.81647 kcal(IT)/(lb °F) = 1.163x10-3 kWh/(kg K)
  • 1 J/(kg K) = 1 J/(kg °C) = 2.3885x10-4 kcal(IT)/(kg oC) = 2.3885x10-4 Btu/(lb °F) = 1.9501x10-4 kcal(IT)/(lb °F)
  • 1 kcal(IT)/(kg °C) = 1 Btu/(lb °F) = 4186.8 J/(kg K) = 0.81647 kcal(IT)/(lb °F) = 1.163x10-3 kWh/(kg K)
  • 1 kcal(IT)/(lb °F) = 1.2248 Btu/(lb °F) = 1.2248 kcal(IT)/(kg °C) = 5127.9 J/(kg K)
  • 1 kJ/(kg K) = 1 kJ/(kg °C) = 1000 J/(kg K) = 1000 J/(kg °C) = 0.23885 kcal(IT)/(kg °C) = 0.23885 Btu/(lb °F) = 0.19501 kcal(IT)/(lb °F) = 2.7778x10-4 kWh/(kg K)
  • 1 kWh/(kg K) = 0.85985 kcal(IT)/(kg °C) = 0.85985 Btu/(lb °F) = 3.6 kJ/(kg K) 
  • 1 mol of air = 28.96546 g

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  • es: aire calor específico
  • de: spezifische Wärmekapazität Luft
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