How To Calculate Steel Quantity  Steel Quantity Formula  How to Calculate Steel Quantity from Drawing  BBS of Slab  Steel Quantity Calculation
How to Calculate Steel Quantity From Drawing?
Data requires for steel quantity calculation:
1) Plan of Section or Element. (Slab, Beam, Column &
Foundation)
2) Section and Elevation Details.
3) All dimensions must be clear and corelated.
Read More: Steel Quantity Calculation Excel Sheet
General Guidelines To Be Followed In Preparing BBS
 The bars are required to be grouped together for each of the structural units, For e.g. beam, etc.
 In a building structure, the Listing of bars should be done floor to floor.
 For cutting and bending operations, schedules should be provided separately in the form of A4 sheets and should not a part of the detailed reinforcement drawings.
 The form of bar, fabric schedule, and the shapes of the bar used should be according to BS 8666.
 It is always preferable that bars should be listed in numerical order in the schedule for better understanding.
 The bar mark reference on the label which is attached to a bundle of bars refers seperately and uniquly to a specific group of defined length, size, shape, and type used on the job.
 This is very crucial as a bar mark reference can then state to a class of bar characteristics. Similarly, it also helpful in the case of steel fixers and laborers can keep track of the type and number of bars needed to complete a specific work.
Steel Quantity Calculation
Slab Section
Slab Reinforcement Details
Let, us take one example of a slab for steel quantity calculation.
Following Steel Quantity, we have to calculate from drawing.
 Cement Concrete for Slab.
 Centering and Shuttering for Slab.
 Weight of 12mm dia. Bars.
 Weight of 8mm dia. Bars.
 Prepare Bar Bending Schedule.
(Note: Weight of Steel
bars 12mm — @ 0.9 kg / m
8 mm — @ 0.4 kg/m,
Slab Steel Quantity Calculation Estimation Sheet
Sr. No.Item DescriptionNo.Length (m)WidthHeightQuantity1Cement Concrete for Slab (1:1.5:3):L = 4 + 0.23 + 0.23 = 4.46 m14.463.460.121.85 cu mB = 3 + 0.23 + 0.23 = 3.46
(See drawing in to in dimension (without the wall) of the slab is given 3 m x 4 m. For calculating Quantity of slab concrete we have to calculate out to out the dimension of the slab.)
2
Centering & Shuttering for Slab:
Bottom
1
4.00
3.00
— 12.00
cu m
Sides
2
4.46

0.15
1.34
cu m
( Take 30mm Extra Above
Slab Thickness)
2
3.46

0.15
1.04
cu m
Total
14.38
cu m
(Formwork Quantity is calculated in a square meter. There is one bottom portion and 4 side shuttering. For bottom we have in to in dimension of slab 3m x 4m. For Side formwork, there is 2 different dimensions, 2 with 4 m side and 2 with 3 m sides. For the total length we have to add wall width of both sides to get the total length.)
Read More: Estimation of a Building with Plan
Steel Quantity Formula
312 mm dia main Steel bars @ 150 mm c/c Alternate bent up. L = 3 + 0.23 + 0.23 + (2 x 9 x 0.012) — (2 x 0.05) L = 3.58 (Straight Length) (For finding out nos. of the bar we have to calculate the straight length of the main bar without adding extra length due to bent up) Span = 4 + 0.23 + 0.23 — (2 x 0.05)
= 4.36 m No. of Bars = (4.36/0.15) + 1
= 30 nos. Extra Length of Bent up:
X — Value
Extra Length =
0.45 X X
= 0.12(Slab Thickness) — 2 x 0.02 (Top & Bottom Cover) — 0.012/2(Harf dia
top) — 0.012/2( Half dia bottom) X
= 0.12 2 x 0.02–0.012/2–0.012/2 = 0.068 m L
= 3.58 + 0.45X
L = 3.58 + 0.45 x 0.068
3.6130 3.61 @0.90 97.47 kg
(In case
of bent up bars are provided on both sides, we have to add 0.45 X twice in
length)
4
8 mm dia. Distribution steel @ 180 mm c/c
Bars
at Bottom:
Hook
Length = 9d
= 9 x 0.008
= 0.072