Calculate the exact weight of Round Bars, Rods, and Solid Cylinders instantly with our free online calculator. Simply enter your diameter and length in mm or inches, and get accurate results in both kg and lbs for Mild Steel (MS), Stainless Steel (SS), Aluminium, Copper, and other common metals.

Weight Calculation for Round Bar and Rod

The weight of a Round Bar (also known as a Rod, Shaft, or Solid Cylinder) is determined by its cross-sectional area, length, and material density. Unlike hollow pipes, round bars are solid throughout, making them essential for machining, structural reinforcement, axles, and fasteners. The standard density for Mild Steel is 7.85 g/cm³, while other materials like Aluminium (2.70 g/cm³) and Copper (8.96 g/cm³) have significantly different weights for the same dimensions. Accurate weight calculation is critical for material procurement, logistics planning, scrap valuation, and precise cost estimation in engineering and fabrication projects.

Round Bar Weight Formula and Manual Calculation

The industry-standard formula for calculating round bar weight is based on the volume of a cylinder:

Weight (kg) = π × (Diameter/2)² × Length (m) × Density Factor

Simplified for direct diameter input in millimetres:

Weight (kg) = Diameter² (mm) × Length (m) × 0.000006165 (for Mild Steel)

Density Factors for common materials:
0.000006165 for Mild Steel (MS) & Carbon Steel
0.00000623 for Stainless Steel (SS 304/316)
0.00000212 for Aluminium
0.00000704 for Copper
0.00000647 for Brass

For imperial units (inches and lbs):

Weight (lbs) = Diameter² (in) × Length (ft) × 0.222 (for Steel)

Step-by-Step Calculation Example

  • Step 1: Identify dimensions: Diameter = 25 mm, Length = 2 m (Mild Steel)
  • Step 2: Calculate Cross-Sectional Area: π × (12.5)² = 3.1416 × 156.25 = 490.87 mm²
  • Step 3: Apply simplified formula: 25² × 2 × 0.000006165 = 625 × 2 × 0.000006165
  • Step 4: Result: 1250 × 0.000006165 = 7.71 kg
  • Step 5: Compare with Aluminium: 7.71 × (2.70/7.85) ≈ 2.65 kg

This calculation aligns exactly with the results provided by the round bar weight calculator in kg.

Metal Round Bar Weight Chart (Quick Reference per Metre)

Diameter (mm) Mild Steel (kg/m) Stainless Steel (kg/m) Aluminium (kg/m) Copper (kg/m)
10 mm0.62 kg0.63 kg0.21 kg0.70 kg
12 mm0.89 kg0.90 kg0.30 kg1.01 kg
16 mm1.58 kg1.60 kg0.54 kg1.79 kg
20 mm2.47 kg2.50 kg0.85 kg2.80 kg
25 mm3.85 kg3.90 kg1.33 kg4.38 kg
32 mm6.31 kg6.39 kg2.17 kg7.17 kg
50 mm15.42 kg15.60 kg5.30 kg17.52 kg

Frequently Asked Questions

What is the formula for Round Bar weight in kg?

The formula for Round Bar weight in kg is: Weight = Diameter² (mm) × Length (m) × 0.000006165 for Mild Steel. This simplified constant is derived from the density of steel (7.85 g/cm³) and the geometric formula for the area of a circle.

How much does a 16mm MS rod weigh per meter?

A standard 16mm Mild Steel rod weighs approximately 1.58 kg per metre. This is calculated using the formula: 16 × 16 × 0.000006165 = 1.578 kg. This value is widely used in construction for estimating reinforcement steel requirements.

Is there a difference between a Round Bar and a Rod?

In general fabrication, "Round Bar" and "Rod" are used interchangeably to describe a solid cylindrical metal stock. However, "Rod" is often used for smaller diameters or specific applications like welding rods or rebar, while "Bar" typically refers to larger stock used for machining shafts or structural components. The weight calculation remains identical for both.