Unit Conversion

In Civil Engineering it may be on Construction Site while Executing any project or doing calculation in studies or in structural engineering while designing a structures or it may be in any field, it becomes problem when you are not familiar with the basics units. So In this short blog you will be able to convert any units to other unit without memorizing each one. If you know about the most basics unit then you can convert and manipulate bigger units and calculation by just using these concepts.

One thing to remember is if you convert a bigger unit to Smaller one the you have to Multiply with equivalent value and from smaller to bigger one then divide the equivalent value. The following example will clear your concepts.

(1) Linear or One Dimensional (1D) Unit

Length, Distance, Displacement

1st you should know about one linear or dimensional units and these are the basics to convert to any others units if 2D (Area) & 3D(Volume) e.g foot, meters and inches ect if you don’t know about these basics then you can learn it by using a measuring tape (inchi tap). These are basics then you can convert bigger linear units e.g Km, miles etc. You can see here the feets, inches and soot (soother) on the upper part and meters, cm and mm on the lower part horizontally.

Measuring Tap

(2) Two Dimensional(2D) Units

Area, surface area, cross-sectional area

So Area is a 2 Dimensional quantity and you can find these units by just squaring of the one dimensional or linear units e.g taking square of m you will got m2 and the same way all other units. It can convert from MKS (meter, kilogram,second) to FPS (Foot,pound Second).

(a)Example: Convert=>5m2 to ft3 => 20m2 = 20 (1*3.28)2 =20*10.76 ft2= 215.2ft2(here using only linear units and converted from bigger to smaller that’s why multiplied)

(b)Example: Convert=>50ft2 => m2 = 50* (1/3.28)2 =50*0.0929 ft2= 4.645m2 (here using only linear units and converted from smaller to bigger units that’s why divide)

(3) Three Dimensional (3D)


Volume is a Three Dimensional Unit and you received that unit by taking cube of 1d units e.g if you take cube of ft then it will become ft3 which is 3d unit. It can be converted any 3d units of MKS(meter, kilogram, second) to FPS(foot,pound, second) with the help of linear units without memorize the exact relation between them.

(b)Example: Convert=> 5m3 to ft3 => 5m3 = 5 (1*3.28)3 =5*35.3 ft3=176.4ft3 (here using only linear units and converted from bigger to smaller that’s why multiplied )

(b)Example: Convert=>40ft3 => m3 = 40* (1/3.28)2 =40*0.028 ft3= 1.12m2 (here using only linear units and converted from smaller to bigger units that’s why divide)

(4) Force/Weight/Load

Force,weight and load are same terms used in Civil Engineering and general units used for that is Newton(N), Kg, Pound (lb), KN, Kip(kilo-pound).

If you know about the most basics one e.g 1 Kg=10 N, 1 kg= 2.205 lb then you can convert any units with the help of these tow.

Examples: Convert=>

  • 10 kg=> N=> 10 kg= 10 *10 N = 100 N (multiplied; Bigger=>Smaller)
  • 200 lb=>KN=> suppose here we don’t know about the lb and KN relation then 1st we will convert lb to know unit that we know. So taking help from “1 kg = 10 N” & “1 kg= 2.205 lb” , 1 lb= (1/2.205) kg= 0.4535 kg , now convert the 0.4535kg into N ; 0.4535*10 N= 4.535N Now convert it to KN(divide by 1000); 0.004535 KN. So 1 lb=0.004535 KN. Now 200 lb= 200 *0.004535 KN = 0.91 KN.

The same way you can convert things without any single relations known.

(5) Stresses (Force/Area) and Densities (Force/Volume) and Moment/Torque (Force *Distance0

So if you have learnt about how to convert forces and 1d(length), 2D(area), 3d(Volume) units then you can easily convert the units of stresses, Densities and Moments/ torques etc.

So we will solve one example for stresses

Examples: Convert=> 1Mpa to Psi

Mpa= N/mm2 and Psi= lb/in2 ; 1 N/mm2 ; So suppose here I don’t know about lb and N relation then taking help of know relations e.g 1 kg = 10 N=> 1 N= 0.1 Kg now replace the kg by pound (lb) because we know that relation; 1 N= 0.1 ( 2.205 lb)=> 1N= 0.2205 lb and the same way convert mm2 to in2 => suppose we don’t know the relations between mm to in then; 1mm2= (1/1000)2 = 1o-6 m2; converted into meters because we know the relation between meter to ft; 10-6 (3.28)2 ft2 = 0.00001076 ft2 now convert that feets to inches; 0.00001076*(12)2 in2= 0.001549 in2 .

Now put the values of 1 N= 0.2205 lb and 1mm2= 0.001549 ; 1 N/mm2(MPa)= 0.2205 lb/0.001549 in2 (Psi)=> 1 N/mm2=143 Psi but exactly it is equal to 145 Psi as I put values approximately.

so from the above example you may have cleared that only know the basics concepts you can derive any units.

Watch the Video given below I have discussed it briefly;


==========Thank You==========