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Let’s take a look at the unit weight of TMT bars and how it is calculated. TMT bars (Thermo-Mechanically Treated bars) are one of the most popular and widely sold steel bars in India. TMT bars are used across multiple industries depending on their grades, corrosion resistance and tensile strength. As such, when you buy TMT bars in India, the steel bar weight is vital to ensure fair pricing. TMT bars are usually found in four grades and their sizes range from 8mm to 32mm. Quite naturally, even for the same grade of TMT (e.g., Fe500), the price of a unit weight of 10 mm rod and that of a 12mm rod will be different.

We take a closer look at the unit weight of TMT rods, its meaning, how to calculate rod weight, and how it affects steel cost.

Unit weight of steel TMT bars – 8mm, 12mm, 16mm, 25mm, 32mm

We’ll take a close look at the meaning and how unit weight of steel bars is calculated in the next section. For now, here’s a look at the unit weight of steel TMT bars from 8mm steel bars onwards.

TMT bar size (diameter) Unit weight (kg/m)* Approx. weight of a single bar (kg)* Approx. price of a single bar (₹)*
8mm 0.395 2.47 ₹40 – ₹50
10mm 0.617 3.85 ₹60 – ₹70
12mm 0.888 5.56 ₹90 – ₹100
16mm 1.579 9.87 ₹150 – ₹160
20mm 2.466 15.41 ₹220 – ₹230
25mm 3.853 24.08 ₹350 – ₹360
32mm 6.313 39.45 ₹550 – ₹560

*Values are approximates and for reference only. It may differ based on the manufacturer and region. Price indicated does not include GST, freight and will change by region and brand. For accurate information contact your seller, or get a quote from us at Tata nexarc.

What is the meaning of unit weight of TMT bar?

The unit weight of TMT bars or any steel rod refers to the weight of a single bar. This is usually expressed in kilograms per metre (kg/m).

It refers to the mass of the TMT for a specific length. In general, the most commonly available and used TMT bars range between 8mm to 32mm.

TMT bars are commonly used in construction and infrastructure development projects. The steel bar unit weight as such is important, as it helps to estimate the total weight of TMT steel required for the project. To ensure that the steel structure being built adheres to the design and safety requirements, the length of the bars and the number of pieces required are essential for calculating overall steel requirement.

For any project, TMT steel is therefore bought by pieces or the number of steel rods and the weight, i.e., kg or metric tons.

Also read: Daily steel rates – Agni TMT steel price

How to calculate unit weight of TMT steel rods?

Before we look into how steel bar weight is calculated, here are some basic things to keep in mind:

  • The weight of TMT bars are usually calculated in kilograms (kg) or tons (where 1 ton = 1000kgs)
  • A standard TMT bar length is 12 meters
  • There is some weight tolerance of bars as per IS guidelines
  • As per BIS, high strength deformed steel bars for concrete reinforcement are grouped as:
Group 1 Group 2 Group 3 Group 4
Fe415, Fe415D, Fe415S Fe500, Fe500D, Fe500S Fe550, Fe550D Fe600

Also read: IS code for steel

Formula to calculate unit weight of steel bars (TMT)

The formula to calculate unit weight of steel bars is based on the dimensions and density of the bars.

Formula for calculating unit weight of TMT:

Unit weight (kg/m) = (π*D²*L^ρ) / 4

Where:

Π (Pi) is approximately 3.147

D is the diameter of the bar in meters

L is the length of the bar in meters

Ρ (rho) is the density, i.e., for steel it is typically 7850 kg/m³

For example (here L = 1 meter or 1000 mm)

Weight of steel bar = Volume of bar (V) x Density of steel (D)

= (Cross sectional area of bar x Length) x 7850 kg/m³

= ((3.14 x (D² x L) / 4) x 7850 kg/m³)

= (3.14 x D²/4 x 1000 x 7850) / (1000 x 1000 x 1000)

= D² x 0.006162

When we reciprocate the decimal, we get = 162.2

Alternative formula for calculation weight of TMT bar:

W = D² L / 162

Here:

D is the diameter in mm

L is the length of the steel bar in meters

Using this simple formula, the weight of 8 mm steel bar would be (approximately):

W =  8² x 12 / 162 = 4.74 kgs

(here L = 12 and D = 8)

Note – Variation of +/- 7 is applicable

Also read: Unit weight of steel bars – How to calculate with weight formula

Unit weight of 8 mm steel

Let us check how the steel rod weight varies based on the length of the bar.

We start with 8mm TMT steel bars.

Unit weight of 8mm TMT = D² x 0.006162 = 8 x 8 x 0.006162 = 0.395

Weight of 8mm bars:

In all cases we use the basic formula W = D² x L / 162.

8mm TMT Length (L) 6m 8m 10m 12m
Weight in kg 2.37 3.16 3.95 4.74

*Horizontal – Varying length of steel bars for 8mm diameter TMT. Results in kg.

Unit weight of 10 mm rod

Next, we look at unit 10 mm rod weights. In general, 8mm and 10mm steel bars act as load bearers in a structure. Common applications can be seen in slabs, staircases, etc.

Unit weight of 10mm TMT = D² x 0.006162 = 10 x 10 x 0.006162 = 0.616

Weight of 10mm bars:

Using formula W = D² x L / 162.

10mm TMT Length (L) 6m 8m 10m 12m
Weight in kg 3.07 4.94 6.17 7.41

*Horizontal – Varying length of steel bars for 10mm diameter TMT. Results in kg.

Unit weight of 12 mm rod

12mm steel rods and those up to 25mm have capacity to withstand higher external weight loads. They are as such often used in beams and columns. Let’s look at 12mm rod weights.

Unit weight of 12mm TMT = D² x 0.006162 = 12 x 12 x 0.006162 = 0.887

Weight of 12mm bars:

Using formula W = D² x L / 162

12mm TMT Length (L) 6m 8m 10m 12m
Weight in kg 5.34 7.12 8.89 10.67

*Horizontal – Varying length of steel bars for 12mm diameter TMT. Results in kg.

Unit weight of 16 mm TMT rods

We next look at 16mm steel bar weight. 16mm TMT bars are commonly used in construction and infrastructure development projects, especially for the construction of residential and commercial buildings.

Unit weight of 16mm TMT = D² x 0.006162 = 16 x 16 x 0.006162 = 1.577

Weight of 16mm bars:

Using formula W = D² x L / 162

16mm TMT Length (L) 6m 8m 10m 12m
Weight in kg 9.48 12.64 15.80 18.96

*Horizontal – Varying length of steel bars for 16mm diameter TMT. Results in kg.

Unit weight of 20 mm bars

Fe 500 grade TMT bars of 20mm are often used in construction projects. TMT bars can help reduce construction costs, a reason why they are a popular choice of steel for all construction projects. Let’s take a look at 20mm rod weight.

Unit weight of 20mm TMT = D² x 0.006162 = 20 x 20 x 0.006162 = 2.46

Weight of 20mm bars:

Using formula W = D² x L / 162

20mm TMT Length (L) 6m 8m 10m 12m
Weight in kg 14.81 19.75 24.69 29.63

*Horizontal – Varying length of steel bars for 20mm diameter TMT. Results in kg.

Unit weight of 25 mm steel TMT

A 25mm TMT bar price can be around ₹66 – ₹70/kg depending on the location, brand and length of bar (e.g., check price list of Amman TMT steel products). Popular grades for 25mm TMT bars are Fe500, Fe500D, Fe550D and Fe600.

Unit weight of 25mm TMT = D² x 0.006162 = 25 x 25 x 0.006162 = 3.85125

Weight of 25mm bars:

Using formula W = D² x L / 162

25mm TMT Length (L) 6m 8m 10m 12m
Weight in kg 23.15 30.86 38.58 46.30

*Horizontal – Varying length of steel bars for 25mm diameter TMT. Results in kg.

Unit weight of 32 mm steel TMT

When you buy 32mm steel bars, it’s recommended to check if the seller has a minimum order quantity. In most cases, the best rates and deals are offered on meeting the MOQ or going for bulk orders.

Unit weight of 32mm TMT = D² x 0.006162 = 32 x 32 x 0.006162 = 6.31

Weight of 32mm bars:

Using formula W = D² x L / 162

32mm TMT Length (L) 6m 8m 10m 12m
Weight in kg 37.93 50.57 63.21 75.85

*Horizontal – Varying length of steel bars for 32mm diameter TMT. Results in kg.

Buying steel by steel bar weight

Now that you understand how to calculate the unit weight of TMT bar, here are some factors to keep in mind when you buy steel.

  • Price of TMT bars will be based on the region, i.e., steel price in Mumbai and Pune will vary from the price of steel in Delhi, Chennai or any other city.
  • The manufacturer’s brand will determine the final price of the bar, e.g., price of Kamdhenu steel will be different from the price of steel by Jindal Steel. This is usually because of the certifications acquired (e.g., BIS and IMS) and the premium the brand charges for it.
  • Always check the availability of steel, especially if you are undertaking a long-term project. Since you will be requiring the product in batches, it is recommended to find a reliable steel supplier who can procure it for you.
At Tata nexarc we have tied up with verified sellers across the country to make it easy for you to buy steel at the best prices. You can get instant prices for TMT bars, stainless steel, coils, sheets, galvanised steel and more. On-time delivery, credit facility available. Order now.