Electrical Calculators

Kilowatt-Hour (kWh) Calculator

Calculate kilowatt-hours and energy cost for any appliance or device. Enter watts, hours of use, and your electricity rate for instant results.

Electricity Cost Calculator

See the daily, monthly, and annual electricity bill impact of running any device. Plug in wattage, hours, and your utility rate for a full cost breakdown.

Appliance Electricity Cost Calculator

See what an appliance costs per day and over the days you enter, with the annual figure at 365 days. Enter its wattage, daily hours, days and your rate.

Air Conditioner Running Cost Calculator

Estimate what your air conditioner costs to run per day, month, and year from its BTU rating and SEER or EER, with duty cycle and your own rate built in.

Space Heater Running Cost Calculator

Estimate the running cost of a 750-1,500 W electric-resistive space heater, factoring in the thermostat duty cycle and your local electricity rate.

Electricity Bill Estimator

Estimate a monthly electricity bill from four categories (HVAC, water heating, refrigeration, other) and your all-in rate, with defaults from RECS 2020.

EV Charging Cost Calculator

Calculate the true cost of charging an electric car at home or on the road. Side-by-side Level 1 vs Level 2 vs DC Fast comparison with cost per mile.

Water Heater Electricity Cost Calculator

Compare tank, tankless, and heat pump water heater operating costs with DOE UEF math. Inputs: gallons/day, set temp, inlet temp, and rate.

Inverter Cable Size Calculator

Find the right cable gauge for your battery-to-inverter connection. Enter inverter watts, voltage, and distance for safe wire sizing.

Wire Distance Calculator

Calculate voltage drop and recommended wire gauge for any distance. Enter amps, distance, voltage, and target drop percentage.

Voltage Drop Calculator

Calculate voltage drop in any wire run. Enter wire gauge, distance, current, voltage and system to compare the drop with the NEC voltage drop note.

Motor FLA Calculator

Look up motor full-load amps from the printed NEC motor table for single-phase and three-phase motors, with the 125 percent conductor figure.

Amps Draw Calculator

Calculate current draw in amps from watts and volts for any device. Supports single-phase and three-phase loads with power factor adjustment.

Locked Rotor Amps (LRA) Calculator

Find motor locked rotor amps (LRA) from the nameplate code letter, horsepower and voltage, or place a nameplate LRA in its code letter band.

HP to Watts Calculator

Convert horsepower to watts and watts to HP instantly. Supports mechanical, electrical, and metric horsepower with precise conversion factors.

Electrical Load Calculator

Dwelling service load by the optional method, line by line as municipal worksheets print it, with amperes and the next standard overcurrent rating.

Fusing Transformer Calculator

Find the maximum primary and secondary fuse for a transformer of 1000 V and under from its kVA, voltages and protection scheme.

kVA to Amps Calculator

Convert kVA to amps for single-phase and three-phase systems. Enter kVA and voltage for the current; add your power factor to see the true power in kW.

Generator Sizing Calculator

Find the right generator size for your loads. Enter running watts and the highest starting watts to get running and peak watts, with a margin on the peak.

Breaker Size Calculator

Find the breaker size for any load in amps, with the matching copper wire gauge for NM cable or conduit. Covers general circuits and feeders, not motors.