Electrical
Calculators.
Free precision tools — no signup, no ads.
Electricity Cost
Estimate monthly electricity cost by appliance usage
Wire Size
Select the right wire gauge for your electrical circuit
Voltage Divider
Design voltage divider circuits with resistor values
Ohm's Law
Calculate voltage, current, and resistance using Ohm's Law
LED Resistor
Calculate the right resistor for LED circuits
Resistor Color Code
Decode resistor values from color bands or find colors
Generator Sizing Calculator
Size a backup generator by your power requirements
Circuit Breaker Size Calculator
Calculate the right breaker size per NEC code
Conduit Fill Calculator
Calculate conduit fill percentage per NEC standards
Solar Panel Size Calculator
Calculate how many solar panels you need by usage
EV Charger Sizing Calculator
Size EV charger circuits per NEC 625 — breaker size, wire gauge, panel capacity, and charging time for Level 1 and 2 EVSE
Electrical Panel Load Calculator
Calculate residential electrical panel load per NEC Article 220 with demand factors, service sizing, and capacity analysis
Lighting Layout Calculator
Calculate recessed light fixture count and spacing for any room using the zonal cavity method — foot-candles, lumens, and grid layout
Ground Fault Calculator
Check NEC 2020 GFCI and AFCI requirements by room type — determine required outlet count, applicable code sections, and protection costs