Free Electrical Engineering Calculators
Professional-grade tools for voltage drop, wire sizing, conduit fill, breaker sizing, arc flash analysis, and more. Built for NEC and IEC compliance.
Most Popular
The tools electrical engineers use every day
Voltage Drop
Calculate voltage drop and NEC/IEC compliance
Wire Sizing
Determine minimum conductor size per ampacity tables
Conduit Fill
Calculate raceway fill percentage per code
Breaker Sizing
Size circuit breakers per NEC continuous load and next-size-up rules
Arc Flash
Incident energy, hazard category, and PPE per IEEE 1584
Motor Calculator
FLC, protection sizing, and overload per NEC 430
Grounding
GEC and EGC sizing per NEC Article 250
Transformer Sizing
Primary/secondary current and protection sizing
All Calculators
28 tools organized by category
Power Analysis
Load calculations, power factor, harmonics, and energy analysis
Transformer Sizing
Primary/secondary current and protection sizing
Demand Factor
NEC 220 demand factor analysis for service sizing
Power Factor Correction
Calculate capacitor bank kVAR for PF improvement
Ohm's Law
Calculate voltage, current, resistance, or power from any two known values
Power Calculator
Real, apparent, and reactive power for DC, 1Ø, and 3Ø circuits
HP ↔ kW
Convert horsepower to kilowatts with motor efficiency and current estimation
Harmonics Analyzer
THD, true RMS, neutral current, and IEEE 519 compliance
Load Schedule
Build load schedule with demand factors and service sizing per NEC 220
Wiring & Raceway
Conductor sizing, voltage drop, conduit fill, and cable management
Voltage Drop
Calculate voltage drop and NEC/IEC compliance
Wire Sizing
Determine minimum conductor size per ampacity tables
Conduit Fill
Calculate raceway fill percentage per code
AWG ↔ mm²
Convert between AWG wire sizes and metric mm² areas with IEC mapping
Cable Pulling
Calculate pulling tension, bend factors, and sidewall pressure per NEC Ch.9
Cable Tray Fill
Cable tray fill compliance per NEC 392 for ladder/ventilated/solid trays
Raceway Fill
Conduit fill per NEC Chapter 9 Tables 1, 4, and 5
Protection & Safety
Breaker sizing, fault current, arc flash, and grounding
Motor Calculator
FLC, protection sizing, and overload per NEC 430
Short Circuit
Point-to-point fault current calculation
Grounding
GEC and EGC sizing per NEC Article 250
Breaker Sizing
Size circuit breakers per NEC continuous load and next-size-up rules
Arc Flash
Incident energy, hazard category, and PPE per IEEE 1584
Fault Current
Available fault current and minimum AIC rating per IEEE 141
Motor Starting
Inrush current and VD analysis for DOL/Y-Δ/Soft/VFD methods per NEC 430
System Design
Lighting, UPS, solar, battery backup, and system utilities
Lighting Design
Fixture quantity and layout using zonal cavity method
Energy Cost
Estimate electricity cost by usage hours, rates, and demand charges
Unit Converter
Universal electrical unit converter: V, A, Ω, W, J, Hz, F, H
UPS Sizing
Size UPS with battery capacity, redundancy (N/N+1/2N), and heat output
Solar Sizing
Size solar PV: panel count, inverter rating, battery bank per NEC 690
Battery Backup
Size battery banks with DOD, temperature derating, and common sizes
Learning Resources
Guides, formulas, scenarios, and expert articles for electrical professionals
Trusted by Electricians & Engineers
Built for professionals who need accuracy, speed, and code compliance.
“ElectraKit replaced three apps I was juggling on job sites. The NEC voltage drop and wire sizing tools alone save me 30 minutes per panel schedule.”
“I spec commercial projects across NEC and IEC jurisdictions. Having both standards in one platform with automatic compliance checks has been invaluable.”
“The System Generator eliminated my spreadsheet chains. I can model a full distribution panel and get coordinated breaker + cable sizing in minutes.”
System Generator
Go beyond individual calculations. Build complete Load → Protection → Cable chains with auto-sizing, compliance checking, and shareable PDF reports.