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Physical Measurement Laboratory / Sensor Science Division

Fundamental Thermodynamics Group

Pressure and Gas Flow Unit Conversions

Pressure

Unit	Pa	mbar	Torr	psi	atm	in H₂O	in Hg
1 Pa	1	0.01	7.50062E-03	1.45038E-04	9.86923E-06	4.01463E-03	2.95300E-04
1 mbar	100	1	0.750062	0.014504	9.86923E-04	0.401463	2.95300E-02
1 Torr (mm Hg)	133.3224	1.333224	1	0.0193368	1.31579E-03	0.535240	3.93701E-02
1 psi	6894.757	68.94757	51.7149	1	6.80460E-02	27.67990	2.03602
1 atm	101325	1013.25	760.000	14.6959	1	406.782	29.9213
1 in H₂O	249.0889	2.490889	1.86832	0.0361273	2.45832E-03	1	7.35559E-02
1 in Hg	3386.389	33.86389	25.4000	0.491154	3.34211E-02	13.5951	1

For a additional pressure units, click here.

Gas Flow

Unit	atm cc/s	sccm	mbar l/s	torr l/s	slm	Pa m³/s	kg Mol/s
1 atm cc/s	1	60	1.01325	0.760	0.06	0.101325	4.45E-05
1 sccm	0.0166667	1	0.0168875	0.0126667	0.001	0.001689	7.45E-07
1 mbar l/s	0.986923	59.2154	1	0.750062	0.059215	0.1	4.41E-05
1 torr l/s	1.31579	78.9474	1.333224	1	0.078947	0.133322	5.85E-05
1 slm	16.6667	1000	16.8875	12.6666637	1	1.68875	7.45E-04
1 Pa m³/s	9.86923	592.154	10	7.50062	0.592154	1	4.41E-04
1 kg Mole/s	2.25E+04	1.34E+06	2.27E+04	1.71E+04	1.34E+03	2.27E+03	1

Unit	cfm	l/min	l/sec	m³/hrs
1 cfm	1	28.31685	0.471948	1.699011
1 l/min	0.035315	1	0.016667	0.06
1 l/sec	2.11888	60	1	3.6
1 m³/hrs	0.588578	16.66667	0.277778	1

The volume flow units, which contain "atm", assume that the gas is:

ideal
at a pressure of 101325 Pa
at a temperature of 0 °C

Be aware that the unit "atm cm³/min", which is sometimes abbreviated "sccm" (standard cubic centimeter per minute), sometimes assumes a different temperature.

For approximating, remember that: