Conversion Factors for Units of Stress and Pressure (Small Units)


Metric Units British Units

Millibar
(mb)
Normal atmosphere (atm) Milimetre of mercury
(mm Hg)
Kilogram-
force per sq. m
(kgf/m2)
or
(mm H2O)
Poundal per sq. ft.
(pdl/ft2)
Pound-
force per sq. ft.
(lbf/ft2)
Inch of mercury
(in Hg)
Inch of water
(in H2O)

1 Millibar
(mb)
1 9.869 x 10-4 0.750 06 10.197 2 67.197 2.0885 4 0.029 5300 0.401 463
 
1 Normal atmosphere (atm)
1.013 25
x 103
1 7.600 0
x 102
1.033 23
x 104
6.808 7
x 104
2.116 22
x 103
29.921 3 4.067 82
x 102
 
1 Milimetre of mercury
(mm Hg)
1.333 22 1.315 79
x 10-3
1 13.595 1 89.589 8 2.784 50 0.039 3701 0.535 24
 
1 Kilogram-
force per
sq. m
(kgf/m2) or
(mm H2O)
0.098 066 5 9.678 4
x 10-5
0.073 556 1 6.589 8 0.204 816 2.895 90
x 10-3
0.039 370 1
 
1 Poundal per sq. ft.
(pdl/ft2)
0.014 881 6 1.468 70
x 10-5
0.011 162 1 0.151 751 1 0.031 081 0 4.394 55
x 10-4
5.9744
x 10-3
 
1 Pound-force per sq. ft.
(lbf/ft2)
0.178 803 4.725 41
x 10-4
0.359 131 4.882 43 32.1740 1 0.014 139 0 0.192 222
 
1 Inch of mercury
(in Hg)
33.863 9 0.033 421 1 25.4 3.453 16
x 102
2.275 55
x 100
70.726 1 13.595 1
 
1 Inch of water
(in H2O)
2.490 89 2.458 32
x 10-3
1.868 32 25.4 1.673 80
x 102
5.202 3 0.073 556 1