CrossSectional Area Calculator
Table of contents
What is a crosssection and how to calculate a crosssectional area?How to find crosssectional area?Example: Using the crosssectional area calculator.Applications of crosssection shapesFAQsThe crosssectional area calculator determines the area for different types of beams. A beam is a very crucial element in construction. The loadbearing member of bridges, roofs, and floors in buildings are available in different crosssections. Read on to understand how to calculate crosssectional area of I section, T section, C beam, L beam, round bar, tube, and beams with rectangular and triangular crosssections.
What is a crosssection and how to calculate a crosssectional area?
A crosssection is defined as the common region obtained from the intersection of a plane with a 3D object. For instance, consider a long circular tube cut (intersect) with a plane. You'll see a couple of concentric circles. The concentric circles are the crosssection of a tube. Similarly, the beams — L, I, C, and T — are named based on the crosssection shape.
In order to calculate the area of a crosssection, you need to look at them as basic shapes. For instance, a tube is a concentric circle. Therefore, for a tube with inner and outer diameter (d and D) having thickness t, the area of the crosssection can be written as:
$A_\mathrm{C} = \pi \times (D^2d^2)/4$
We also know that the inner diameter d is related to thickness t and outer diameter D as:
$d = D  2 t$
Therefore, the area of crosssection becomes:
$A_\mathrm{C} = \pi \times (D^2  (D  2 t)^2)/4$
Similarly, the area of the crosssection for all other shapes having width W, height H, and thicknesses t₁ and t₂ are given in the table below.
Section  Area 

Hollow Rectangle  (H × W)  ((W  2t₁) × (W  2t₂)) 
Rectangle  W × H 
I  2 × W × t₁ + (H  2 × t₁) × t₂ 
C  2 × W × t₁ + (H  2 × t₁) × t₂ 
T  W × t₁ + (H  t₁) × t₂ 
L  W × t + (H  t) × t 
Isosceles Triangle  0.5 × B × H 
Equilateral Triangle  0.4330 × L² 
Circle  0.25 × π × D² 
Tube  0.25 × π × (D²  (D  2 × t)²) 
How to find crosssectional area?
Follow the steps below to find the crosssectional area.
 Step 1: Select the shape of crosssection from the list, say, Hollow rectangle. An illustration of the crosssection and the related fields will now be visible.
 Step 2: Enter the width of the hollow rectangle,
W
.  Step 3: Fill in the height of the crosssection,
H
.  Step 4: Insert the thickness of the hollow rectangle,
t
.  Step 5: The calculator will return the area of the crosssection.
Example: Using the crosssectional area calculator.
Find the crosssectional area of a tube having an outer diameter of 10 mm
and a thickness of 1 mm
.

Step 1: Select the shape of crosssection from the list, i.e., Tube.

Step 2: Enter the outer diameter of tube,
D = 10 mm
. 
Step 3: Insert the thickness of the tube,
t = 1 mm
. 
Step 4: The area of the crosssection is :
$A_\mathrm{C} = \pi \times (D^2  (D  2 t)^2)/4$$A_\mathrm{C} = \pi \times (10^2  (10  2 \times 1)^2)/4 = 28.274\ \text{mm}^2$
Applications of crosssection shapes
Did you know?
 An I or H beam is used extensively in railway tracks.
 T beams are found in use in early bridges and are used to reinforce structures to withstand large loads on floors of bridges and piers. See our beam load calculator to learn more!
How to calculate crosssectional area of a pipe?
To calculate crosssection of a pipe:
 Subtract the squares of inner diameter from the outer diameter.
 Multiply the number with π.
 Divide the product by 4.
How to calculate area of an I section?
The area of I section with total width W
, height H
, and having thickness t
can be calculated as:
Area = 2 × W × t + (H  2 × t) × t
How to calculate area of an T section?
The area of a T section with total width W
, height H
, and having thickness t
can be calculated as:
Area = W × t + (H  2 × t) × t
What is the cross section of a cube?
The crosssection of a cube is a square. Similarly, for a cuboid, it is either a square or a rectangle.