Air - Specific Heat vs. Temperature at Constant Pressure

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

• Isobaric specific heat (C_p) is used for air in a constant pressure (ΔP = 0) system.
• Isochoric specific heat (C_v) 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 - C_P and C_V - 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 c_p = 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 C_p = 1.006 kJ/kg K (equal to kJ/kg ^oC) or 0.2403 Btu(IT)/lb °F  - is better

Online Air Specific Heat Calculator

The calculator below can be used to estimate the specific heat of air 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)/(lb_m*°R)

Temperature

Choose the actual unit of temperature: °C  °F  K  °R 

Choose the actual pressure:  1 bara / 14.5 psia; 10 bara / 145 psia; 50 bara / 725 psia; 100 bara / 1450 psia;

See also other properties of Air at varying temperature and pressure: Density and specific weight at varying temperature, Density at varying pressure, Diffusion Coefficients for Gases in Air, Prandtl Number, Specific heat at varying pressure, Thermal Conductivity, Thermal Diffusivity, Properties at gas-liquid equilibrium conditions and Air thermophysical properties at standard conditions and Composition and molecular weight, 
as well as Specific heat  of Ammonia, Butane, Carbon dioxide, Carbon monoxide, Ethane, Ethanol, Ethylene, Hydrogen, Methane, Methanol, Nitrogen, Oxygen, Propane and Water.

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Specific heat of air at 1 bar (=0.1 mPa = 14.5 psi):

For full table with Isobaric heat capacity - rotate the screen!

Temperature			Isochoric specific heat (Cv)					Isobaric specific heat (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	0.02093	0.7225	0.0002007	0.1726	0.1406	0.02953	1.022	0.000283	0.24350	0.19930	1.415
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], 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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