# EleCalculator.com

> Free electrical calculators for US electricians, engineers, and students. Tools cover 86+ specialized calculations across 16 categories with NEC reference context where applicable.

## About

EleCalculator.com provides high-precision electrical calculation tools for NEC-based U.S. electrical work. All calculators are free, require no signup, and produce instant results with edition-sensitive NEC pages noting the adopted-code basis that should be verified with the AHJ. The site serves electrical engineers, licensed electricians, contractors, and electrical engineering students.

## Calculator Categories

### Basic Electrical Laws
- [Ohm's Law Calculator](https://elecalculator.com/calculator/basic/ohms-law/): Calculate voltage, current, resistance, and power using Ohm's Law (V=IR, P=VI).
- [Power Calculator](https://elecalculator.com/calculator/basic/power-calculator/): Single-phase and three-phase electrical power calculations (P = VI cos θ).
- [Impedance Calculator](https://elecalculator.com/calculator/basic/impedance-calculator/): AC circuit impedance from resistance and reactance (Z = √(R² + X²)).

### Circuit Analysis
- [Voltage Drop Calculator](https://elecalculator.com/calculator/circuit/voltage-drop/): Voltage drop calculations for copper and aluminum conductors with NEC informational-note context.
- [Series Circuit Calculator](https://elecalculator.com/calculator/circuit/series-circuit/): Analyze series circuit configurations — total resistance, current distribution, power dissipation.
- [Parallel Circuit Calculator](https://elecalculator.com/calculator/circuit/parallel-circuit/): Parallel resistance, current divider, and combined impedance calculations.

### Wire & Cable Sizing
- [Wire Size Calculator](https://elecalculator.com/calculator/wire/wire-size/): Select correct AWG wire size based on current, voltage drop, and NEC 310.15 derating.
- [Ampacity Calculator](https://elecalculator.com/calculator/wire/ampacity-calculator/): NEC Table 310.16 conductor ampacity with temperature and conduit fill derating.
- [Conduit Fill Calculator](https://elecalculator.com/calculator/wire/conduit-fill/): NEC Chapter 9 conduit fill percentage — EMT, IMC, RMC, PVC.

### Motors & Loads
- [Load Calculator](https://elecalculator.com/calculator/motor/load-calculator/): Electrical load calculations for service entrance and feeder sizing.
- [Motor Current Calculator](https://elecalculator.com/calculator/motor/motor-current/): Motor FLA from NEC Table 430.248/430.250, conductor and protection sizing.
- [Motor Starting Current Calculator](https://elecalculator.com/calculator/motor/motor-starting-current/): Inrush current estimation for DOL, star-delta, soft starter, and VFD starting methods.

### Safety & NEC Compliance
- [Short Circuit Calculator](https://elecalculator.com/calculator/safety/short-circuit/): Available fault current calculations for electrical system protection coordination.
- [Breaker Sizing Calculator](https://elecalculator.com/calculator/safety/breaker-sizing/): NEC 240.4/210.20/430.52 circuit breaker sizing with conductor protection verification.
- [Arc Flash Calculator](https://elecalculator.com/calculator/safety/arc-flash/): Incident energy and arc flash boundary calculations per IEEE 1584.
- [Grounding Calculator](https://elecalculator.com/calculator/safety/grounding-calculator/): NEC Article 250 grounding electrode system calculations.

### Power Systems
- [Transformer Calculator](https://elecalculator.com/calculator/power/transformer-calculator/): Transformer sizing, impedance, and voltage regulation calculations.
- [Power Factor Calculator](https://elecalculator.com/calculator/power/power-factor/): Power factor analysis with kW, kVA, kVAR power triangle.
- [Power Factor Correction](https://elecalculator.com/calculator/power/power-factor-correction/): Capacitor bank sizing for power factor improvement.

### Testing & Measurement
- [Insulation Resistance Calculator](https://elecalculator.com/calculator/testing/insulation-resistance/): Temperature-corrected insulation resistance testing with pass/fail criteria.
- [Current Shunt Calculator](https://elecalculator.com/calculator/testing/current-shunt/): Shunt resistor selection for current measurement applications.

### Residential Electrical
- [NEC 220 Demand Factor Calculator](https://elecalculator.com/calculator/residential/nec-220-demand-factor/): NEC Table 220.55 cooking equipment, 220.42 lighting, and 220.44 receptacle demand factors.
- [Electrical Panel Load Calculator](https://elecalculator.com/calculator/residential/electrical-panel-load/): Residential panel load analysis and service sizing.
- [Electrical Service Size Calculator](https://elecalculator.com/calculator/residential/electrical-service-size/): Determine required service entrance capacity per NEC Article 220.

### Renewable Energy
- [Solar Calculator](https://elecalculator.com/calculator/renewable/solar-calculator/): Solar panel system sizing, energy production, and ROI estimation.
- [Battery Capacity Calculator](https://elecalculator.com/calculator/renewable/battery-capacity/): Battery bank sizing for backup and off-grid systems.
- [UPS Backup Time Calculator](https://elecalculator.com/calculator/renewable/ups-backup-time/): UPS runtime estimation based on load and battery capacity.

### Conversion Tools
- [Resistor Color Code Calculator](https://elecalculator.com/calculator/tools/resistor-color-code/): 4-band and 5-band resistor color code decoder.
- [Capacitor Code Calculator](https://elecalculator.com/calculator/tools/capacitor-code/): 3-digit ceramic capacitor code to pF/nF/µF conversion.

## Technical Standards

All calculators reference the following standards where relevant:
- NFPA 70, National Electrical Code (edition adopted by the AHJ)
- IEEE 1584 (Arc Flash)
- NEMA standards for motor and equipment ratings
- NEC Tables 310.16, 430.248, 430.250, 220.55

## Languages

- English (default): https://elecalculator.com/
- Spanish: https://elecalculator.com/es/