Instantly calculate the weight and cost of TMT steel bars for construction projects.
6 mm
8 mm
10 mm
12 mm
16 mm
20 mm
25 mm
32 mm
40 mm
Standard TMT bar sizes used in construction.
Standard factory length is usually 12 meters.
Please enter a valid length greater than 0.
Total number of steel bars required.
Quantity must be at least 1.
Current market rate per kg of steel.
Total Steel Weight
106.67 kg
Weight Per Meter
0.89 kg/m
Total Length
1200 m
Estimated Cost
6,933.55
Calculation based on standard formula: W = (D² / 162) × L
Calculation Breakdown
Parameter
Value
Unit
Weight Comparison (Standard Sizes)
Comparison of weight per meter across different standard TMT bar diameters.
What is a TMT Steel Weight Calculator?
A tmt steel weight calculator is an essential engineering tool used by civil engineers, construction contractors, and site supervisors to estimate the total mass of reinforcement steel required for a project. "TMT" stands for Thermo-Mechanically Treated bars, which are the industry standard for concrete reinforcement due to their high tensile strength and ductility.
Calculating the exact weight of steel is crucial because steel is sold by weight (usually in tons or kilograms), not by length or piece count. However, construction drawings specify reinforcement in terms of length and diameter. This calculator bridges that gap, allowing professionals to convert drawing specifications into procurement orders accurately.
Common misconceptions include thinking that all 12mm bars weigh exactly the same regardless of the manufacturer. While the tmt steel weight calculator uses the theoretical standard density of steel (7850 kg/m³), actual weights may vary slightly (±3-5%) based on rolling tolerances permitted by IS:1786 standards.
TMT Steel Weight Calculator Formula and Explanation
The core logic behind any accurate tmt steel weight calculator relies on a derived formula that simplifies the volume-to-mass conversion. The standard density of steel is approximately 7850 kg/m³. Instead of calculating volume ($\pi r^2 h$) and multiplying by density every time, engineers use a simplified formula:
Weight (kg) = (D² / 162) × L
Here is the derivation and breakdown of the variables:
Weight (W): The resulting mass of the steel bar in kilograms.
Diameter (D): The thickness of the bar in millimeters (mm).
Constant (162): Derived from $162.2$, which comes from calculating the weight of a 1 meter bar of 1mm diameter using the density of 7850 kg/m³. (Calculation: $1 / (0.00785 \times \pi / 4)$).
Length (L): The total length of the steel bar in meters.
Variables Reference Table
Variable
Meaning
Unit
Typical Range
D
Diameter of Bar
Millimeters (mm)
6mm to 40mm
L
Length of Bar
Meters (m)
1m to 12m (Std)
Unit Weight
Weight per unit length
kg/meter
0.22 to 9.86 kg/m
Practical Examples (Real-World Use Cases)
Example 1: Residential Column Reinforcement
Scenario: A contractor needs to order steel for 10 concrete columns. Each column requires 8 bars of 16mm diameter. Each bar is cut to a height of 3 meters.
Using the tmt steel weight calculator, the contractor knows to order roughly 380kg of 16mm steel.
Example 2: Slab Reinforcement Cost Estimation
Scenario: A site engineer estimates a roof slab requires 500 bars of 10mm steel. The standard length of each bar is 12 meters. The current market price is 65 per kg.
Diameter (D): 10 mm
Quantity: 500 bars
Length per Bar: 12 meters
Unit Weight: $10^2 / 162 = 0.617$ kg/m
Total Weight: $0.617 \times 12 \times 500 = 3702$ kg (3.7 Tons)
Total Cost: $3702 \times 65 = 240,630$
This rapid calculation helps in budget allocation and verifying supplier invoices.
How to Use This TMT Steel Weight Calculator
Follow these simple steps to get an accurate estimation:
Select Diameter: Choose the diameter of the TMT bar from the dropdown menu (e.g., 12mm, 16mm). This is usually specified in your structural drawings.
Enter Length: Input the length of a single bar in meters. If you are buying full factory bundles, the standard length is usually 12 meters.
Enter Quantity: Input the total number of bars required.
Input Price (Optional): If you want to estimate the cost, enter the current market price per kilogram in your local currency.
Analyze Results: The calculator will instantly display the Unit Weight (kg/m), Total Weight, and Total Cost.
Use the "Copy Results" button to save the data for your purchase orders or estimation sheets.
Key Factors That Affect TMT Steel Weight Results
When using a tmt steel weight calculator for procurement, consider these influencing factors:
Rolling Tolerances: While the calculator uses theoretical weight ($D^2/162$), manufacturers are allowed a variation of ±3% to ±5% (Sectional Weight Tolerance). Actual steel delivered might weigh slightly less or more than the theoretical calculation.
Steel Grade (Fe415 vs Fe500): The density of steel remains constant (7850 kg/m³) regardless of grade. Whether you use Fe415, Fe500, or Fe550D, the weight calculation remains the same.
Wastage & Lapping: The calculator gives the net weight. In real construction, you must add 3-5% extra for cutting wastage and lapping (overlapping bars to increase length).
Corrosion: Rusted bars may have a slightly different weight due to material loss or oxide accumulation, though for new purchases this is negligible.
Market Rate Fluctuations: The "Total Cost" is highly sensitive to daily market fluctuations. Steel prices change based on global raw material costs (iron ore, coal) and local demand.
Transport & Handling Fees: The calculated cost is usually the material cost. Do not forget to factor in unloading charges and transportation to the site, which can add significant overhead.
Frequently Asked Questions (FAQ)
1. Is the TMT steel weight calculator formula accurate for all brands?
Yes. The formula $D^2/162$ is based on the specific gravity of steel, which is a physical constant. It applies to all brands like Tata Tiscon, JSW, SAIL, etc., provided they adhere to IS standards.
2. Why is 162 used in the steel weight formula?
It is a derived constant. Density of steel is 7850 kg/m³. Weight per meter = Volume × Density = $(\pi \times D^2 / 4000000) \times 7850 \times 1000$ approx reduces to $D^2/162$.
3. Does this calculator work for square or flat bars?
No. This tmt steel weight calculator is specifically for cylindrical (round) TMT bars. Square bars require a different formula ($Volume \times Density$).
4. How much steel is required for a 1000 sq ft house slab?
As a thumb rule, slab reinforcement requires roughly 80kg to 100kg of steel per cubic meter of concrete, or approx 3.5kg to 4kg per square foot of built-up area. For precise numbers, use the calculator with structural drawing data.
5. What is the weight of a 12mm rod of 12 meters?
Using the calculator: $12^2 / 162 = 0.888$ kg/m. For 12 meters: $0.888 \times 12 = 10.66$ kg.
6. Should I calculate weight in kg or tons?
Small residential projects usually deal in kilograms or quintals (100kg). Large commercial projects order in Metric Tons (1000kg). This calculator provides the base kg value which is easily convertible.
7. Can I use this for stainless steel bars?
Generally, yes. Stainless steel has a density very similar to carbon steel (approx 7900-8000 kg/m³), so the $D^2/162$ formula provides a very close approximation (within 1-2%).
8. How do I verify the weight of delivered steel?
Use this calculator to find the theoretical weight. Then, weigh a sample bundle on a physical weighbridge. If the difference is greater than 5%, the steel may be undersized or of poor quality.
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