Calculation of the theoretical weight of steels

The unit for the calculated theoretical weight of steel is kilo grams (kg). The fundamental equation is as follows:W （weight, kg ） = F （cross section area, mm2 ）× L （length， m ）×ρ（density， g/cm3 ）× 1/1000

The density of steel is：7.85g/cm3 ，the equations for calculating the theoretical weight of different kinds of steel are as follows:

Name (unit) Calculation equation Meaning of symbol

Calculation example

Round steelBull rod（kg/m）

W= 0.006165 ×d 2 d = diameter mm

Round steel with diameter of 100 mm, calculate the weight per m. Weight per m= 0.006165 ×1002= 61.65kg

Deformed steel bar （kg/m）

W= 0.00617 ×d 2 d= cross-section diameter mm

Deformed steel bar with a cross-section diameter of 12 mm，calculate the weight per m. Weight per m = 0.00617 ×12 2 = 0.89kg

Square bar（kg/m）

W= 0.00785 ×a 2 a= width of the edge, mm

Square bar with width of the edge of 20 mm, calculate weight per m.Weight per m = 0.00785 ×202= 3.14kg

Flat steel （kg/m）

W= 0.00785 ×b ×d b= width of the edge, mmd= thickness, mm

Flat steel with width of the edge of 40 mm, and thickness of 5mm, calculate weight per m. Weight per m = 0.00785 ×40 ×5= 1.57kg

Hexagonal bar （kg/m）

W= 0.006798 ×s 2 s= distance between opposite edges, mm

Hexagonal bar with distance between opposite edges of 50 mm, calculate weight per m. Weight per m = 0.006798 ×502= 17kg

Octagonal steel（kg/m）

W= 0.0065 ×s 2 s= distance between opposite edges, mm

Octagonal steel with distance between opposite edges of 80 mm, calculate weight per m. Weight per m = 0.0065 ×802= 41.62kg

Equal-angle bar （kg/m）

W= 0.00785 ×[d （2b – d ）+0.215 （R2 – 2r 2 ）]

b= width of the edged= thickness of the edgeR= radius of inner arcr= radius of end arc

Calculate weight per m of an equal-angle bar with size of 20 mm×4mm. R of the 4mm×20 mmequal-angle bar is 3.5, and r is 1.2, as can be found in the catalogue of metallurgical products, then, weight per m = 0.00785 ×[4 ×（2 ×20 – 4 ）+0.215 ×（3.52 – 2 ×1.2 2 ）]= 1.15kg

Angle steel with unequal legs （kg/m）

W= 0.00785 ×[d （B+b – d ）+0.215 （R2 – 2 r 2 ）]

B= width of the longer edgeb= width of the shorter edged= thickness f the edge

Calculate the weight per m of an angle steel with unequal legs with size of 30 mm×20mm×4mm. The R of an unequal angle with size of 30 ×20 ×4 is 3.5, r is 1.2，as can be found in the catalogue of

R= radius of the inner arcr= radius of the end arc

metallurgical products, then weight per m = 0.00785 ×[4 ×（30+20 – 4 ）+0.215 ×（3.52 – 2 ×1.2 2 ）]= 1.46kg

Channel steel （kg/m）

W=0.00785 ×[hd+2t （b – d ）+0.349 （R2 – r 2 ）]

h= heightb= length of the legd= thickness of the waistt= average thickness of legsR= radius of inner arcr= radius of end arc

Calculate weight per mof a channel steel of size of 80 mm×43mm×5mm. The t of this channel steel is 8, R is 8, and r is 4, as can be found in the catalogue of metallurgical products, then, weight per m = 0.00785 ×[80 ×5+2 ×8 ×（43 – 5 ）+0.349 ×（82–4 2 ）]= 8.04kg

Steel I-beam（kg/m）

W= 0.00785 ×[hd+2t （b – d ）+0.615 （R2 – r 2 ）]

h= heightb= length of legsd= thickness of waistt= average thickness of legsR= radius of inner arcr= radius of end arc

Calculate weight per m of a steel I-beam of a size of 250 mm×118mm×10mm.Thetofthis I-beam is 13, R is 10, and r is 5 , as can be found in the manual of metallurgical materials, then, weight per m =0.00785 ×[250 ×10+2 ×13 ×（118 –10 ）+0.615 ×（102 –5 2 ）]= 42.03kg

Steel plate （kg/m2）

W= 7.85 ×d d= thickness steel plate of a thickness of 4mm, calculate weight per m2. Weight per m2 = 7.85 ×4= 31.4kg

Steel pipe（including seamless steel pipe and welded steel pipe）（kg/m）

W= 0.02466 ×S （D – S ）

D= outer diameterS= thickness of the wall

Seamless steel pipe of an outer diameter of 60 mm and thickness of the wall of 4mm,calculate weight per m. Weight per m = 0.02466 ×4 ×（60 –4 ）= 5.52kg

Source : http://www.east-steel.com/03.htm