Electricity Calculators
Home electricity calculators: appliance running cost, standby drain, LED payback, AC bills, generator runtime, breaker sizing, and panel load.
What things cost to run, and what a panel can carry. 15 calculators, aimed at the bill rather than at the wiring. Code-level sizing work lives under Electrical.
LED payback has become a more interesting calculation than it was, because the easy wins are gone. Swapping an incandescent for an LED paid back in months. Swapping a working CFL for an LED often takes years, since the efficiency gap is far smaller, and replacing a bulb that still works throws away the remaining life you already paid for. The page handles the second case honestly rather than assuming every swap is worth doing.
Standby power is the quiet one. A single device drawing 5 watts continuously is about 44 kWh a year. Ten such devices around a house is a real line on the bill for equipment doing nothing, and the fix costs nothing but a switched strip.
Every page takes your tariff, and the ones that matter take time-of-use rates separately. In countries with peak and off-peak pricing, when an appliance runs can change its annual cost by a factor of two or three, and a flat average rate hides the entire opportunity.
Air Conditioner Electricity Cost
Calculate your air conditioner monthly electricity cost from BTU rating, SEER or EER efficiency, daily runtime hours, and your electricity rate.
Appliance Running Cost Calculator
Calculate the daily, monthly, and annual electricity cost of any home appliance. Enter wattage, hours per day, and your utility rate to see the bill impact.
Circuit Breaker Load Capacity Calculator
Check what an installed breaker can carry and whether a new load fits, using the NEC 80% continuous rule and the wire already in the wall.
Electric Heating Cost Calculator
Calculate the electricity cost of heating a room from size, insulation, temperature difference, heater efficiency, and rate. Shows daily and monthly cost.
Electric Water Heater Running Cost
Find the daily and annual electricity cost of your electric water heater. Enter tank size, daily usage, temperature rise, efficiency rating, and utility rate.
Extension Cord Amp Rating & Safety Check
Check if your extension cord is rated for the load. Enter AWG gauge, cord length, and device wattage to verify amp capacity and calculate voltage drop.
Generator Fuel Consumption & Runtime
Estimate generator fuel consumption and runtime from rated wattage, load percentage, fuel type, and tank size. Covers gasoline, propane, and diesel generators.
Home Battery Backup Sizing Calculator
Size a home battery backup system from essential load wattage and desired backup hours. Shows required kWh capacity and equivalent battery bank size.
LED Upgrade Payback Calculator
Calculate when an LED upgrade pays for itself. Enter old bulb wattage, LED wattage, daily hours, electricity rate, and bulb cost to find the payback period.
Panel Capacity and Headroom Calculator
Check how much of your panel is used and what is left, comparing a connected load in kilowatts against the rating and the 80% continuous limit.
Peak Demand Charge Calculator
Calculate a commercial electricity bill with peak demand charges. Enter peak kW demand, demand rate, monthly kWh, and usage rate to see the cost breakdown.
Pool Pump Electricity Cost
Calculate pool pump electricity cost from motor horsepower, efficiency, daily run time, and electricity rate. Compare single-speed vs variable-speed savings.
Smart Thermostat Savings Calculator
Estimate annual heating and cooling savings from a smart thermostat setback schedule. Enter your monthly bill, setback degrees, and hours per day.
Standby Power Cost Calculator
Estimate the annual cost of standby power drain from devices left plugged in. Enter standby wattage, number of devices, and your electricity rate.
Time-of-Use Rate Savings Calculator
Calculate monthly electricity bill savings by shifting loads from peak to off-peak hours. Enter kWh usage, percentage shifted, and peak versus off-peak rates.