Different series have slightly different densities. Standard is 2.70 g/cm³.
Enter the diameter of the round bar in millimeters.
Please enter a valid positive diameter.
Enter the length of the bar in millimeters (1000mm = 1m).
Please enter a valid positive length.
Total number of bars required.
Quantity must be at least 1.
Optional: Current market price per kg for estimation.
Total Estimated Weight
5.30 kg
Based on formula: V × Density
Single Bar Weight:5.30 kg
Total Volume:1963.50 cm³
Total Estimated Cost:23.85
Specification Breakdown
Parameter
Value
Unit
Weight Comparison: Aluminium vs Steel
Aluminium is approximately 1/3 the weight of steel for the same volume.
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What is "Calculate Weight of Aluminium Round Bar"?
To calculate weight of aluminium round bar means to determine the mass of a cylindrical solid aluminium object based on its dimensional properties and alloy density. This calculation is a critical step in engineering, manufacturing, and procurement.
Engineers perform this calculation to ensure structural loads remain within safety limits, while procurement managers use it to estimate shipping costs and raw material prices. Unlike flat sheets, round bars require a calculation involving the area of a circle ($\pi r^2$) multiplied by length to find the volume first.
Common misconceptions include assuming all aluminium alloys weigh exactly the same (they vary slightly) or confusing the diameter with the radius in the volume formula.
Formula and Mathematical Explanation
The math behind this calculator relies on standard geometric volume formulas combined with material density principles.
Step 1: Calculate Volume
The volume ($V$) of a cylinder (round bar) is calculated as:
$V = \pi \times r^2 \times L$
Where $r$ is the radius (Diameter / 2) and $L$ is the length.
Step 2: Calculate Weight
Once volume is known, weight ($W$) is derived by multiplying volume by density ($\rho$):
$W = V \times \rho$
Variable Definitions
Variable
Meaning
Standard Unit (Metric)
Typical Range
$D$
Diameter
Millimeters (mm)
5mm – 500mm
$L$
Length
Millimeters (mm)
100mm – 6000mm
$\rho$ (Rho)
Density
g/cm³
2.66 – 2.85
Practical Examples (Real-World Use Cases)
Example 1: Automotive Suspension Link
An engineer needs to calculate weight of aluminium round bar for a custom suspension link.
Inputs: Diameter: 40mm, Length: 500mm, Alloy: 6061 (Density ~2.70 g/cm³).
Calculation: Radius = 20mm (2cm). Length = 50cm.
Volume = $3.14159 \times 2^2 \times 50 = 628.3 \text{ cm}^3$.
Weight = $628.3 \times 2.70 = 1696.4 \text{ grams}$ or 1.70 kg.
Example 2: Manufacturing Batch Order
A machine shop orders stock for a production run of 100 pins.
Inputs: Diameter: 25mm, Length: 3000mm (3m standard bar), Quantity: 10.
Financial Impact: Knowing the exact weight helps the shop verify the supplier's quote, which is often priced per kilogram. If the calculated weight differs significantly from the invoiced weight, there may be a discrepancy in the alloy or dimensions delivered.
How to Use This Aluminium Weight Calculator
Select Alloy: Choose the specific grade (e.g., 6061, 7075). If unknown, use the default (Standard).
Enter Dimensions: Input the Diameter and Length in millimeters. Ensure these are accurate to the finished or raw stock size.
Set Quantity: Enter the number of bars if calculating for a batch.
Input Cost (Optional): Add the price per kg to see a total cost estimate.
Analyze Results: View the total weight in the highlighted box and check the chart to compare it against steel.
Key Factors That Affect Results
When you calculate weight of aluminium round bar, several factors influence the final figures:
Alloy Composition: Adding zinc (7000 series) or copper (2000 series) makes the alloy heavier than pure aluminium or magnesium-heavy alloys (5000 series).
Dimensional Tolerances: Extruded bars have tolerances. A "50mm" bar might actually be 50.5mm, which increases weight by ~2% over a long length.
Temperature: While negligible for rough weight, thermal expansion affects volume precision in extreme engineering contexts.
Surface Finish: Anodizing or coating adds negligible weight, but rough cast bars may have inconsistent diameters compared to precision ground bars.
Cost Fluctuations: The financial result depends on the LME (London Metal Exchange) aluminium prices, processing fees, and shipping tariffs.
Scrap Rate: If calculating for purchasing, always add 10-15% extra length for saw cuts (kerf) and chuck gripping in lathes.
Frequently Asked Questions (FAQ)
Does the alloy grade really change the weight significantly?
Yes, for large quantities. 7075 aluminium is about 5% heavier than 6061. On a single small part, it's negligible, but for a ton of material, that's a 50kg difference.
Why do I need to calculate weight of aluminium round bar before ordering?
Shipping costs are often weight-based. Additionally, CNC machines have weight limits for the stock they can spin safely at high RPM.
Is this calculator accurate for hollow tubes?
No. This tool is specifically for solid round bars. Hollow tubes require subtracting the volume of the inner void.
How does Aluminium compare to Steel in weight?
Aluminium is roughly 1/3 the weight of steel. The density of steel is ~7.85 g/cm³ compared to aluminium's ~2.70 g/cm³.
What is the formula for calculating cost?
Cost = Total Weight (kg) × Price per kg. Always ensure your price input includes tax if applicable.
Can I use this for metric and imperial conversions?
This calculator accepts millimeters. To convert inches to mm, multiply by 25.4.
Why is the result slightly different from my supplier's invoice?
Suppliers often bill based on "theoretical nominal weight" which might round up, or the physical bars might be slightly oversized (oversize tolerance) to allow for machining.
Does length include the saw cut?
No. The input length is the physical length of the material. If you need 10 pieces of 100mm, you need more than 1000mm total stock to account for the saw blade thickness.