John S. Cooper
        CSci, CChem, CWEM, FCIWEM, MRSC, DipWEM

    Consultant on Water, Wastewater
    & Environmental Management                                

| Home | About Us | ServicesExpert Witness | Fees | Availability | H & S Policy | Curriculum Vitae | Clients | Useful Links | Formulae | Factors | Contact Us |


John S. Cooper - Consultancy Services

Conversion Factors


The following table gives imperial and metric (SI) conversion factors for a number of parameters employed in water and wastewater treatment.   Whilst the use of imperial units is now outdated it has been our experience that data (eg. design criteria, drawings, operation manuals, etc.) relating to some older treatment systems may still refer to imperial units.   Hence the inclusion of this table on our website.


Imperial Unit Multiplier Metric Unit Reciprocal
Acre 0.4047 Hectare 2.471
Btu 1.055 kJ 0.9478
Btu/ft2h 3.155 J/m2s 0.3170
Btu/ft3 37.26 kJ/m3 0.0268
Btu/gal 0.2321 kJ/l 4.31
Btu/h 0.2931 W(J/h) 3.412
Btu/lb 2.326 kJ/Kg 0.43
oF 0.5555(oF - 32) oC (1.8 x oC) + 32
ft 0.3048 m 3.281
ft/min 5.08 mm/s 0.1969
ft/s 0.3048 m/s 3.281
ft2 0.0929 m2 10.76
ft2/ft3 3.28 m2/m3 0.305
ft3 0.02832 m3 35.31
ft3/ft2 0.3048 m3/m2 3.281
ft3/gal 6.23 m3/m2 0.1605
ft3/lb 0.0624 m3/kg 16.1
ft3/mil gal 0.00623 m3/103m3 160.51
ft3/min 0.000472 m3/s 2119
ft3/min ft 0.00155 m3/s m 645.86
ft3/min ft2 0.00508 m3/s m2 196.85
ft3/s (cusec) 0.02832 m3/s (cumec) 35.31
gal 4.546 litre 0.220
gal 0.004546 m3 220
gal/ft 0.0149 m3/m 67.114
gal/ft2 0.049 m3/m2 20.408
gal/ft2 h 1.176 m3/m2 d 0.850
gal/ft2 min 70.56 m3/m2 d 0.0142
gal/min 0.0758 l/s 13.192
gal/yd2 0.005437 m3/m2 183.9
gal/yd3 0.005946 m3/m2 168.2
hp 0.7457 kW 1.341
hp/mil gal 0.164 W/m3 6.098
in 25.40 mm 0.03937
in2 645.2 mm2 0.00155
in3 16.39 x 103 mm3 0.061 x 10-3
lb 0.4536 kg 2.205
lb/ft2 4.881 kg/m2 0.2049
lb/ft3 16.03 kg/m3 0.06243
lb/103ft3 0.016 kg/m3 62.5
lb/in2 0.06895 bar 14.503
lb/yd3 0.5932 kg/m3 1.686
mil gal 4546 m3 0.220
mil gal/acre 1.123 m3/m2 0.890
mile 1.609 km 0.6214
ton 1.016 tonne 0.9842
yd 0.9144 m 1.094
yd2 0.8361 m2 1.196
yd3 0.7646 m3 1.308

Miscellaneous Conversion Factors

US Gallon  =  0.8327 UK Gallon  =  3.7853 Litres  

UK Gallon  =  1.2009 US Gallon  =  4.5458 Litres

ton/ft2 = 107.4 kN/m2


© John S. Cooper 2008