Electrical Calculators

Free online electrical calculators and sizing references for engineers, electricians, and students. Each tool comes with the formula, a worked example, and the relevant standard, so you can check the result rather than just trust it. Start with the groups below, or browse every tool underneath.

Cable Sizing and Conversion

• DC Cable Size Calculator for solar, battery, and off-grid systems
• AS/NZS 3000 Cable Sizing Table Explained
• Street Light Cable Size Chart (NEC and IEC)
• kW vs kVA Cable Sizing
• AWG to mm² Conversion Chart
• All cable tools

Voltage Drop

• Landscape Lighting Voltage Drop Calculator for 12V and 24V systems

Motor Calculators

• Motor Current Calculator from kW/HP
• Motor Torque Calculator
• Motor Protection Calculator
• NEMA Motor Data Calculator

Busway and Bus Duct

• Bus Duct Size Calculator
• DC Busway Size Calculator

Clearance and Insulation

• Phase to Phase Clearance Calculator (IEC 61439)
• Altitude Correction Factor Clearance Calculator

Quick Reference

Motor current (three-phase): I = P ÷ (√3 × V × power factor × efficiency), with P in watts and V as line voltage. Voltage drop: keep it low, because it matters most on long runs and low-voltage systems like 12V and 24V lighting or solar. The NEC informational notes suggest about 3% on a branch circuit and 5% overall, and other standards set their own limits. Always verify: calculators give an estimate, so confirm results against your local code and the manufacturer’s data before installing. For the code behind the numbers, see our Electrical Standards guides.

All Electrical Calculators