Free Wire Size Calculator for India to estimate cable size in mm², current, MCB rating and voltage drop for copper and aluminium wires. Useful for electricians, ITI students and electrical wiring.
Calculated Current: - A
Recommended MCB: - A
Estimated Voltage Drop: - V
Allowed Voltage Drop: - V
Suggested Wire Size: - mm²
Note: ये मान सामान्य IS/IEC अनुमानों पर आधारित हैं। Final selection installation method, insulation, ambient temp, grouping आदि पर निर्भर है—local codes follow करें।
This wire size calculator estimates the electrical current, MCB rating, voltage drop, and suggested wire size in mm² and AWG based on the load, voltage, power factor, efficiency, distance, and conductor material.
Understanding these basic electrical calculations can help electricians, ITI students, electrical technicians, and homeowners make a preliminary wire size selection before final verification.
The following formulas are used to estimate the current for single-phase and three-phase electrical loads:
Cable length affects voltage drop. As the distance between the supply point and the electrical load increases, the voltage drop can become more significant. Therefore, long cable runs should be checked carefully for voltage drop before selecting the final wire size.
Copper and aluminium have different electrical properties. The conductor material affects resistance, voltage drop, current-carrying capacity, connections, and the required cable size for a particular application.
Important: This calculator provides a quick preliminary estimate. Final wire or cable selection should consider the actual installation method, insulation type, ambient temperature, cable grouping, conductor characteristics, voltage drop requirements, protective-device coordination, manufacturer data, and applicable electrical standards.
Choosing the correct wire or cable size is not based on wattage alone. A practical cable-size check should consider electrical load, current, system voltage, cable length, conductor material, installation method and allowable voltage drop.
The calculator result is a preliminary estimate. Final electrical design should be verified for the actual installation conditions.
Common residential wiring projects use conductor sizes such as 1.5 mm², 2.5 mm², 4 mm² and 6 mm². The appropriate size depends on the circuit load, installation method, cable length, temperature, grouping, voltage drop and applicable requirements.
| Wire Size | Common Example Application | Important Note |
|---|---|---|
| 1.5 mm² | Lighting and fan circuits | Verify load and installation conditions. |
| 2.5 mm² | General socket/power circuits | Verify actual load and protective-device coordination. |
| 4 mm² | Higher-load circuits | Check current capacity and voltage drop. |
| 6 mm² | Larger loads and some sub-main applications | Final size depends on design conditions. |
| 10 mm² and above | Main/sub-main and higher-load applications | Require proper design verification. |
This is a general educational reference, not a universal ampacity chart. Always verify actual installation conditions and applicable standards.
Wire size and protective-device selection should be considered together. A basic workflow is:
Load → Current → Cable/Wire Size → Voltage Drop → MCB Verification
An MCB should not be selected simply by matching appliance wattage. Verify the protective device against the circuit, cable and applicable installation requirements.
Voltage drop is the reduction in voltage along a cable caused by conductor impedance. It becomes more important as cable length and load current increase.
This calculator uses the selected allowable voltage-drop percentage to estimate the maximum permitted drop. Long cable runs may require a larger conductor after the voltage-drop calculation is checked.
Copper and aluminium have different electrical and physical properties. For a comparable application, conductor size and installation requirements can differ between the two materials.
| Factor | Copper | Aluminium |
|---|---|---|
| Conductivity | Higher for the same cross-sectional area | Lower for the same cross-sectional area |
| Conductor size | Often smaller for a comparable application | May require a larger cross-sectional area |
| Weight | Heavier | Lighter |
| Connections | Use suitable terminals and installation practices | Use compatible terminals/connectors and proper installation practices |
Quick reference (approximate). Actual ampacity installation conditions पर depend करती है.
| AWG | Approx. mm² | Typical Copper Ampacity* (A) |
|---|---|---|
| 14 | ~2.08 | 15–20 |
| 12 | ~3.31 | 20–25 |
| 10 | ~5.26 | 30–35 |
| 8 | ~8.37 | 40–55 |
| 6 | ~13.30 | 55–75 |
| 4 | ~21.15 | 85–95 |
| 2 | ~33.62 | 115–130 |
*Indicative only. Local codes और installation conditions के हिसाब से vary कर सकता है.
A wire size calculator is a tool that estimates a suitable conductor size using inputs such as load, voltage, power factor, distance, conductor material and allowable voltage drop.
Estimate the circuit current first. Then check the cable's current-carrying capacity and voltage drop for the actual cable length and installation conditions.
Yes. As cable length increases, voltage drop can become more significant, and a larger conductor may be required when the selected voltage-drop limit is exceeded.
mm² means square millimetres and represents the conductor cross-sectional area. For example, 2.5 mm² means approximately 2.5 square millimetres of conductor area.
A wire gauge calculator helps relate AWG sizes to approximate conductor cross-sectional areas in mm². AWG is a different sizing system from metric mm².
Yes, power factor and efficiency inputs can be used for an initial motor-load calculation. Starting current, protection and installation conditions may require additional engineering verification.
Yes. Select Copper or Aluminium in the calculator. Final selection should still be checked against manufacturer data and actual installation conditions.
It can be used as an educational and preliminary calculation tool for residential loads. Final selection must be verified for the actual installation.
Tool created by Misba Uddin Barbhuiya (Electrician & Electrical Wiring Teacher). Goal: safe, practical wiring knowledge in simple Hindi.