Electrician Calculators
15 free professional-grade tools. Professional electrical calculators for electricians
Wire & Cable
Voltage Drop Calculator
Calculate voltage drop for copper and aluminum wire based on wire size, length, and load current per NEC.
Wire Size Calculator
Determine minimum wire size (AWG) for your circuit based on load current, distance, and voltage drop per NEC.
Wire Ampacity Calculator
Look up allowable ampacity for copper and aluminum wire per NEC Table 310.16, with ambient derating.
Conduit Fill Calculator
Calculate conduit fill percentage and max conductors per NEC Chapter 9. Supports EMT, PVC with THHN, THWN, XHHW wire.
Grounding Conductor Size Calculator
Size equipment grounding conductor per NEC Table 250.66 and NEC Table 250.122 for grounding electrode and equipment grounding conductors.
Load & Circuit
Electrical Load Calculator
Calculate total electrical load for residential and small commercial buildings following NEC Article 220.
Fault Current Calculator
Calculate available fault current at transformer terminals per NEC 110.24. Includes conductor impedance drop for load-side estimates.
Motor Full Load Current Calculator
Look up 3-phase motor full load amps (FLA) per NEC Table 430.250 and calculate conductor ampacity, OCPD, and disconnect ratings.
Transformer Sizing Calculator
Size a 3-phase transformer for a given continuous and non-continuous load following NEC Article 450 and NEC 215.2.
Power & Energy
Ohm's Law Calculator — V, I, R & Power (Free Online Tool)
Calculate voltage, current, resistance, and power using Ohm's Law. Enter any two known values and the calculator solves for the third plus power.
Watts to Amps Calculator
Convert watts to amps for DC, single-phase, and three-phase circuits. Enter power, voltage, and power factor to calculate current draw.
Electricity Cost Calculator
Calculate the cost to run any electrical appliance. Enter power, hours, and rate to estimate monthly and yearly costs.
LED Energy Savings Calculator
Calculate energy savings from upgrading to LED. Estimate annual cost reduction, CO2 savings, and payback period.
Power Factor Correction Calculator
Calculate capacitor kVAR needed to improve power factor to target. Reduce demand charges and improve system efficiency with proper power factor correction.
Solar Panel ROI Calculator
Estimate solar panel payback and lifetime savings. Calculate annual production, net cost after incentives, and 25-year ROI.