Slabs are plan structures whose thickness is quite small as compare to another dimension. Slabs are mostly used in roof covering and floor in various shapes like square, rectangle, or circular. But here we will calculate only the estimate of the steel rod for Slab.
Slab are of two types:-
- One way slab
- Two way Slab
I have explained the difference between both slabs in the previous article in detail. Here we will only discuss “How to calculate steel quantity for slab?”
Let us take an example, we have to calculate the quantity of steel of slab having dimension 30 feet as long span and 15 feet as short span. The Longest side steel rod is called the main rods while the shortest side steel rods are called distribution bars.


We will complete the numerical in three steps given below.
Step-One- (Calculate Total number of different size of bars)
Step-One- (Calculate Total Length of different size of bars)
Step-One- (Calculate Total weight of different size of bars)
Remember That, the formula to calculate the weight of steel rod is given by,
W= D2/52.9 x Total Length (If the length is in feet and diameter is in mm)
and, W=D2/152.25 x Length (If the length is in meter and diameter in mm)
Here the length is in feet so, we will use the formula for length in feet.




Watch video to calculate quantity of steel rods in circular slab
I hope this article on “How to calculate steel quantity for slab” remains helpful for you.
Happy Learning – Civil Concept
Contributed by,
Civil Engineer – Ranjeet Sahani
Read Also,
Calculate weight of steel bar | Quantity of steel bar in circular slab
Minimum clear cover for slab, column, beam, Retaining Structure
Quick guide to design of one way slab with IS Code 456:2000
What makes one-way slab and two-way slab different from each other
From the example 2 how did you get that No’s of main bars =(61)