Standard metric wire sizes. Check cable jacket for markings.
Estimated market value for bright copper wire scrap.
Price cannot be negative.
Total Estimated Copper Weight
0.00 kg
Based on density of 8.96 g/cm³
Estimated Value
$0.00
Weight per Meter
0.00 kg/m
Total Copper Volume
0.00 cm³
Breakdown of value and weight at different length intervals based on current inputs.
Length Segment
Copper Weight (kg)
Estimated Value ($)
Figure 1: Copper Value accumulation vs. Weight accumulation over specified length.
What is how to calculate copper weight in cable?
Knowing how to calculate copper weight in cable is a fundamental skill for electricians, scrap metal dealers, and quantity surveyors. It refers to the process of determining the pure mass of copper conductor contained within an insulated cable, excluding the weight of PVC insulation, steel armoring, or rubber sheathing.
This calculation is primarily used by two groups: contractors estimating the structural load of cabling trays and supports, and recyclers determining the scrap value of stripped wire. A common misconception is that the total weight of the cable equals the copper weight; in reality, insulation can account for 20% to 60% of the total mass depending on the voltage rating and armoring.
How to Calculate Copper Weight in Cable: Formula and Explanation
The mathematical formula to derive copper weight relies on the volume of the cylinder (the wire) and the specific density of copper. The standard specific gravity (density) of copper is 8.96 g/cm³ (or 8960 kg/m³).
The Core Formula
Weight (kg) = Total Cross-Section Area (mm²) × Length (m) × 0.00896
Step-by-Step Derivation:
Determine the total cross-sectional area (Number of Cores × Area per Core).
Multiply by the length to get the volume in cubic millimeters.
Convert the volume to cubic centimeters (divide by 1000).
Multiply by the density of copper (8.96 g/cm³).
Convert grams to kilograms (divide by 1000).
Variables Table
Key Variables in Copper Calculation
Variable
Meaning
Unit
Typical Range
N
Number of Cores
Count
1 – 5 (Power cables)
A
Cross-Section Area
mm²
1.5mm² – 240mm²
L
Length of Cable
Meters (m)
1m – 1000m+
SG
Specific Gravity
g/cm³
8.96 (Constant)
Practical Examples (Real-World Use Cases)
Example 1: Residential Wiring Scrap
An electrician strips out old wiring from a house renovation. They have 200 meters of standard Twin & Earth cable. The cable has 3 cores (Live, Neutral, Earth), and each core is 2.5 mm².
Total Area: 3 × 2.5 = 7.5 mm²
Calculation: 7.5 × 200 × 0.00896
Result: 13.44 kg of pure copper.
Financial Interpretation: At a scrap price of $7.50/kg, this haul is worth roughly $100.80.
Example 2: Industrial Power Feeder
A quantity surveyor is calculating the load for a cable tray holding a heavy armored cable. The run is 50 meters long. It is a 4-core cable with a massive 120 mm² cross-section per core.
Total Area: 4 × 120 = 480 mm²
Calculation: 480 × 50 × 0.00896
Result: 215.04 kg of copper.
Note: This weight only includes the copper. The surveyor must add the weight of the steel armor and PVC jacket to ensure the cable tray does not collapse.
How to Use This Copper Weight Calculator
To accurately determine how to calculate copper weight in cable using our tool above, follow these steps:
Measure the Length: Input the total length of the cable run in meters. If you have feet, divide by 3.28 to get meters.
Identify Core Count: Count the number of insulated copper wires inside the main sheath. Do not count the outer insulation layers.
Select Wire Size: Look at the cable jacket for a marking like "3G2.5" (meaning 3 cores of 2.5mm²) or "4×50" (4 cores of 50mm²). Select the mm² value from the dropdown.
Set Market Price: Enter the current local scrap price for "Bright Wire" or "Millberry" copper to get an accurate financial estimate.
Analyze Results: Use the chart to visualize how value scales with quantity, and check the "Weight per Meter" metric for quick mental math on site.
Key Factors That Affect Copper Weight Results
When learning how to calculate copper weight in cable, consider these six nuances that affect the final figures:
Conductor Purity: Standard electrical wire is 99.9% pure copper (ETP). Lower grade alloys or CCA (Copper Clad Aluminum) will weigh significantly less and have much lower scrap value.
Insulation vs. Stripping Recovery: If you do not strip the cable, you are selling "insulated wire." Buyers will pay 40-60% less because they have to estimate the copper percentage (recovery rate) themselves.
Tinned Copper: Some marine or industrial cables use tinned copper (silver appearance). This is still copper but may be graded differently at scrap yards due to the tin coating.
Solid vs. Stranded: While the mathematical cross-section (e.g., 2.5mm²) is the same, stranded wire has air gaps. However, the calculation uses the nominal area of copper, so the formula remains accurate for weight, even if the physical diameter varies slightly.
Market Volatility: The financial result of your calculation depends heavily on the LME (London Metal Exchange) copper spot price, which fluctuates daily based on global supply and demand.
Gross vs. Net Weight: This calculator gives the Net copper weight. The Gross weight of the cable including insulation is usually 1.5x to 3x the copper weight.
Frequently Asked Questions (FAQ)
Does the ground wire count in the number of cores?
Yes, if the ground (earth) wire is the same thickness as the live conductors, count it. If it is a reduced earth (thinner), calculate it separately for perfect accuracy, though counting it as a full core is a common estimation shortcut.
How do I convert AWG to mm²?
American Wire Gauge (AWG) is inverse to size. Common conversions: 14 AWG ≈ 2.5mm², 12 AWG ≈ 4mm², 10 AWG ≈ 6mm². Check a conversion chart for precision.
Is the calculated weight 100% accurate?
It is a theoretical estimate based on nominal standards (IEC 60228). Manufacturing tolerances allow the actual copper cross-section to vary slightly, usually within ±1-2%.
Should I burn the insulation off to get the copper?
No. Burning wire is illegal in many jurisdictions, harmful to the environment, and degrades the copper quality (making it "burnt copper" rather than "bright copper"), lowering its value. Always strip mechanically.
Why is the calculator result different from my scale?
If your scale reads higher, you are likely weighing the insulation too. If lower, your cable might be CCA (Copper Clad Aluminum), which is much lighter than pure copper.
Does this formula work for aluminum cable?
No. Aluminum has a specific gravity of roughly 2.7 g/cm³, which is about 30% the weight of copper. You must change the density constant to calculate aluminum weight.
What is "Bright Wire" vs "No. 1 Copper"?
"Bright Wire" (Millberry) is shiny, stripped, unoxidized wire. "No. 1" may have traces of oxidation or solder. "No. 2" is burnt or heavily oxidized. Values differ for each.
How do I calculate copper weight in cable for shielded data cables?
Data cables (CAT5/6) have very thin cores (often 0.2mm²). The formula works, but the copper recovery rate is very low compared to the weight of plastic and shielding foil.
Related Tools and Internal Resources
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