🔌 Cable Sizing Calculator
IEC 60364 / IS 3043Online cable sizing calculator
Calculate a preliminary cable size from load current and voltage-drop limits. The tool considers single-phase or three-phase supply, cable length, power factor, installation method, grouping, and ambient temperature.
Use the IEC 60364 and IS 3043 references as a design aid for cable sizing parameters. Save your cable sizing results. You can import/export Excel files from the online cable sizing tool.
| # | Circuit Name | Load (A) | Voltage (V) | System | Length (m) | Install Method | Grouping | Ambient (°C) | Power Factor | Max VD (%) | Cable (mm²) | Capacity (A) | Volt Drop (V) | VD (%) | Status |
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| Size (mm²) | In Air (A) | In Conduit (A) | Underground (A) | In Trunking (A) | Resistance (mΩ/m) | Reactance (mΩ/m) | Source |
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Cable sizing calculator FAQs
What information is needed to size an electrical cable?
Enter the design load current, system voltage and phase, cable length, power factor, installation method, number of grouped circuits, ambient temperature, and the permitted voltage drop.
Does the calculator check voltage drop?
Yes. It compares the calculated voltage drop with the maximum percentage entered for the circuit and can select a larger cable when current capacity alone is not sufficient.
Is this a replacement for an electrical engineer?
No. The result is a preliminary engineering calculation. Verify the final cable, protective device, short-circuit rating, installation conditions, and regulations with a qualified professional.
How to use a cable sizing calculator
Begin with the design current and supply voltage for each circuit. Select single-phase or three-phase operation, enter the cable run length and power factor, then choose the installation method. Grouping and ambient temperature are used to review the available current-carrying capacity after derating.
Voltage drop is checked against the maximum percentage entered for the circuit. A longer run, higher current, or lower permitted voltage drop may require a larger conductor. The final cable selection must also consider short-circuit withstand, protective-device coordination, conductor material, insulation temperature, installation conditions, and local regulations.
This free tool is intended for preliminary design and educational use. Review every result with the applicable IEC 60364, IS 3043, BS 7671, project specification, and manufacturer data before installation.
Cable sizing methodology and limitations
Caltrical compares the circuit load with the cable's derated current-carrying capacity and checks the calculated voltage drop against the permitted limit. It supports in-air, conduit, underground, and trunking installation methods for single-phase and three-phase circuits.
The built-in example library is copper PVC cable data based on IEC 60364 references. Cable ratings vary with conductor material, insulation, temperature, installation details, harmonics, fault conditions, and manufacturer construction. Treat the result as a preliminary design check, not a certificate or approval.