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, mm
d= 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 edge
d= thickness of the edge
R= radius of inner arc
r= 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 edge
b= width of the shorter edge
d= thickness f the edge
R= radius of the inner arc
r= radius of the end arc
|
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 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= height
b= length of the leg
d= thickness of the waist
t= average thickness of legs
R= radius of inner arc
r= 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= height
b= length of legs
d= thickness of waist
t= average thickness of legs
R= radius of inner arc
r= 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 diameter
S= 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 |
