Useful Information

Pressure Units Conversion

Table of conversion factors for different pressure units:

to go from to kpa multiply by reference
psi 6.89476 as/nzs 1376:1996
bar 100 as/nzs 1376:1996
mbar 0.1 as/nzs 1376:1996
standard atmosphere (atm) 101.325 as/nzs 1376:1996
inch of water (inh2o) 4° c 0.2490826 e.a. rocke
mm of water (mmh2o) 4° c 0.0098064 e.a. rocke
m of water (mh2o) 4° c 9.8064 e.a. rocke
foot of water (fth2o) 4° c 2.9889907 e.a. rocke
kgf/cm2 98.0665 as/nzs 1376:1996
inch of mercury (inhg) std 3.3863837 as/nzs 1376:1996
mm of mercury (mmhg) std 0.13332219 as/nzs 1376:1996
ton-force/inch2 (uk) 15,444.256 as/nzs 1376:1996
short ton-force/inch2 (usa) 13,789.5 r.w. haywood
ton-force/foot2 (uk) 107.25178 as/nzs 1376:1996
short ton-force/foot2 (usa) 95.7605 r.w. haywood
torr 0.13332237 as/nzs 1376:1996
kilopond force/in2 (kip/in2) 6,894.76 as/nzs 1376:1996
kilopond/cm2 (kp/cm2) 98.0665 as/nzs 1376:1996
poundal/in2 (pdl/in2) 0.2142956 as/nzs 1376:1996
dynes/cm2 (dyn/cm2) or barye 1 x 10-4 as/nzs 1376:1996
m sea water (s.g. 1.02502 x 9.80665) 10.05201 values used vary by around 0.2%

Most common conversion factors above except the column of water units are obtained from the Australian Standard for Conversion Factors AS/NZS 1376:1996. The Australian standard is not used for water column values as this standard refers to water at a density of 998.2031 kg/m3 at 20oC where the more conventional practice adopted uses water at its maximum density of 999.97 kg/m3 at a temperature of 4oC. Therefore the column of water conversion factors are referenced from the text "Handbook of Units and Quantities" by E.A. Rocke, 1984. Many digital pressure instruments, particularly those from the USA and UK, use water at 4oC factor.