- 1 bag of cement = .0347 cum
 - 1 sqm = 10.76 sqft
 - 1 inch = 25.4 mm
 - Weight in Kilograms of Mild Steel (Sheet,grill etc.) = (Volume x Density of Mild Steel) = Length x Width x Thickness x 7850 kg/cum. Eg. 2.5 m x 1.25 m x .001 m x 7850 = 24.53 KGs……….. [ Keep a notice on the units ]
 - 1 tonne = 1000 KGs
 - 1 quintal = 100 KGs
 - 1 Acre = 43560 sq. ft = 4046.46 sqm
 - 1 cum = 35.32 cuft
 - Unit Weight of Steel Bar = D^2/162 where D is the diameter of the bar. Eg. 12 mm dia bars, unit weight = 12*12/162 = 0.89 kg/m. [Unit weight in this case is the weight of steel bar per meter ].
 - 1 ton and 1 tonne are different things. 1 ton is US ton which is 907.18 KGs. 1 tonne or 1 MT(usually referred as MT in BOQs) is 1000 KGs.
 - In some cases earthworks will be in % Cum wherein you will need to divide the amount by 100. Eg. Earth work in excavation of foundation trenches or drains, Qty = 24295 %cum Rate = Rs. 9161.6 Amount = 24295*9161.6/100.
 

Standard conversion factors 
INCH = 25.4 MILLIMETRE
FOOT = 0.3048 METRE
YARD = 0.9144 METRE
MILE = 1.6093 KILOMETER
ACRE = 0.4047 HECTARE
POUND = 0.4536 KILOGRAM
DEGREE FARENHEIT X 5/9 – 32 = DEGREE CELSIUS
MILLIMETRE= 0.0394 INCH
METRE = 3.2808FOOT
METRE = 1.0936YARD
Convert USCS into SI Units
| USCS unit X Factor = SI unit | SI symbol | 
| Square foot X 0.0929 = Square meter | M2 | 
| Cubic foot X 0.2831 = Cubic meter | M3 | 
| Pound per square inch X 6.894 = Kilopascal | KPa | 
| Pound force X 4.448 = Newton | Nu | 
| Foot pound torque X 1.356 = Newton meter | N-m | 
| Kip foot X 1.355 = Kilonewton meter | LN-m | 
| Gallon per minute X 0.06309 = Liter per second | L/s | 
| Kip per square inch X 6.89 = Megapascal | MPa | 
Source http://onlinecivilforum.com
