Electricity Cost Calculator
This electricity cost calculator helps you estimate how much it costs to run appliances based on wattage and usage time. Enter your electricity rate and usage to understand energy costs and identify ways to save on your utility bill.
Appliance Details
Energy Cost
Enter appliance details to calculate energy cost.
Understanding kWh and Electricity Billing
Electricity is billed in kilowatt-hours (kWh) — the energy consumed by running 1,000 watts for one hour. A 100-watt light bulb uses 0.1 kWh per hour; run for 10 hours and it consumes 1 kWh. The formula is: kWh = (Watts × Hours) ÷ 1,000. Multiply kWh by your rate to get cost.
The average US residential electricity rate is around $0.12–$0.16 per kWh, though it varies significantly — Hawaii averages over $0.35/kWh while states like Idaho and Louisiana average under $0.10/kWh. Your rate also typically varies by time of use if you are on a tiered or time-of-use plan, with peak hours (evenings) costing more than off-peak hours (nights and weekends).
Power Consumption of Common Appliances
Knowing the wattage of your appliances helps identify where your electricity dollars go. Central air conditioning: 3,000–5,000W (biggest home energy user). Electric water heater: 4,000–4,500W. Clothes dryer: 4,000–5,000W. Refrigerator: 100–400W (runs continuously). Desktop computer: 100–400W. Laptop: 30–70W. LED TV (55"): 80–100W. LED bulb: 8–15W. Smart devices and chargers that stay plugged in can add 5–50W each in standby — "vampire load" that is easy to reduce with smart power strips.
Frequently Asked Questions
How do I find the wattage of an appliance?
Check the label on the appliance itself (usually on the back or bottom), the product manual, or the manufacturer's website. Labels typically show watts directly. If the label only shows amps and volts, multiply them together to get watts (W = A × V). For US appliances, voltage is 120V for standard outlets or 240V for large appliances like dryers and ovens. A device drawing 8.5 amps at 120V uses about 1,020 watts. For devices that vary in usage (like refrigerators that cycle on and off), use the rated wattage for a high estimate, or a smart plug with energy monitoring for a real-world average.
How much does it cost to run a central air conditioner all summer?
A 3-ton central AC unit typically runs at about 3,000–3,500 watts. If it runs an average of 8 hours per day for 90 summer days at $0.13/kWh: 3,250W × 8h × 90 days = 2,340 kWh × $0.13 = about $304 for the season. Actual costs vary based on home insulation, thermostat settings, local climate, and unit efficiency (measured in SEER rating). A high-efficiency unit (SEER 20) can use 40–50% less electricity than an older unit (SEER 10) doing the same cooling work, saving $100–200 per summer.
What are the easiest ways to lower my electricity bill?
Switch to LED bulbs (75–80% less energy than incandescent). Adjust your thermostat 7–10 degrees during sleeping or away hours — saves about 10% annually. Wash clothes in cold water and clean the dryer lint trap every load. Unplug chargers and devices you are not using. Set your refrigerator to 35–38°F and freezer to 0°F — colder settings waste electricity with minimal food safety benefit. Use power strips with timers to kill standby load from entertainment systems. During peak summer heat, run high-wattage appliances (dishwasher, laundry) in the evening when grid demand and TOU rates are lower.