How Do You Calculate Electricity Cost?
The formula for calculating electricity cost is straightforward: Cost = (Watts x Hours Used / 1,000) x Price per kWh. The division by 1,000 converts watts to kilowatts, since electricity is billed in kilowatt-hours (kWh). One kWh equals using 1,000 watts for one hour, or 100 watts for ten hours.
For example, if you run a 1,500W space heater for 6 hours at $0.16/kWh, the daily cost is (1,500 x 6) / 1,000 x $0.16 = $1.44 per day. Over a 30-day month, that heater costs $43.20. Over a full winter season of 120 days, the total reaches $172.80.
Tom Brewer, a retired engineer in Pinewood Falls, ran this calculation on every appliance in his workshop and discovered his old dust collector was costing him $18 per month running six hours a day.
Step-by-Step Example
Suppose Marco Ferreira needs to calculate the electricity cost of running his commercial refrigerator at Marco's Kitchen. The unit draws 350 watts and runs roughly 12 hours per day (cycling on and off). At the local rate of $0.14/kWh:
- Daily kWh: (350 x 12) / 1,000 = 4.2 kWh
- Daily cost: 4.2 x $0.14 = $0.59
- Monthly cost: $0.59 x 30 = $17.64
- Annual cost: $0.59 x 365 = $214.62
If Marco has three identical units, he multiplies by 3: about $643.86 per year total for commercial refrigeration. Knowing this helps him budget for operating costs and evaluate whether upgrading to ENERGY STAR models would pay for themselves.
Common Appliance Wattage Reference
The table below lists typical wattage ratings for common household appliances. These values represent average power draw during active use. Actual wattage varies by brand, model, age, and efficiency rating. Check the label on your specific appliance for the most accurate figure.
| Appliance | Typical Watts | Est. Hours/Day | Est. Monthly Cost* |
|---|---|---|---|
| LED Light Bulb | 10W | 5 | $0.24 |
| Incandescent Bulb (60W equiv.) | 60W | 5 | $1.44 |
| Ceiling Fan | 75W | 8 | $2.88 |
| Laptop Computer | 50W | 8 | $1.92 |
| Desktop Computer | 200W | 8 | $7.68 |
| Television (50" LED) | 100W | 5 | $2.40 |
| Gaming Console | 150W | 3 | $2.16 |
| Refrigerator | 150W | 8 | $5.76 |
| Microwave Oven | 1,000W | 0.5 | $2.40 |
| Dishwasher | 1,800W | 1 | $8.64 |
| Washing Machine | 500W | 1 | $2.40 |
| Clothes Dryer | 3,000W | 1 | $14.40 |
| Window Air Conditioner | 1,400W | 8 | $53.76 |
| Central Air Conditioner | 3,500W | 8 | $134.40 |
| Space Heater | 1,500W | 6 | $43.20 |
| Hair Dryer | 1,800W | 0.25 | $2.16 |
| Electric Oven | 2,500W | 1 | $12.00 |
| Coffee Maker | 900W | 0.25 | $1.08 |
| Vacuum Cleaner | 1,400W | 0.5 | $3.36 |
| EV Charger (Level 2) | 7,200W | 4 | $138.24 |
*Monthly cost estimated at $0.16/kWh, 30 days. Sources: US Department of Energy, ENERGY STAR
What Uses the Most Electricity at Home?
According to the US Energy Information Administration (EIA) Residential Energy Consumption Survey, heating and cooling systems are by far the largest electricity consumers in American homes. Space conditioning accounts for roughly 50% of a typical household's electricity use. After that, water heating takes about 14%, followed by lighting, appliances, and electronics.
The breakdown shifts depending on climate and household size. A family in Phoenix, Arizona spends a much larger share on air conditioning than a household in Portland, Oregon. Similarly, homes with electric water heaters and electric ranges use more electricity than those with gas alternatives. Understanding where your electricity goes is the first step toward cutting costs.
The Biggest Energy Hogs
Central air conditioning can draw 3,500 watts or more while running. On a hot summer day when the unit runs 8 to 10 hours, that single appliance can cost $4.50 to $5.60 per day at the national average rate. Electric clothes dryers at 3,000 watts and electric ovens at 2,500 watts are the next largest consumers, though they typically run for shorter periods. Pool pumps, hot tubs, and EV chargers can also drive up bills significantly.
Phantom Loads Add Up
Devices that draw power while turned off or in standby mode are called phantom loads. The US Department of Energy estimates that phantom loads account for 5% to 10% of residential electricity consumption. Common offenders include cable boxes (20 to 35W in standby), gaming consoles (10 to 15W), and laptop chargers (2 to 5W). Use smart power strips to cut power to devices when not in use.
How to Lower Your Electricity Bill
Reducing electricity costs does not require major renovations. Several low-cost and no-cost strategies can trim your monthly bill by 10% to 30%, according to ENERGY STAR.
Switch to LED Lighting
LED bulbs use about 75% less energy than incandescent bulbs and last 25 times longer. Replacing ten 60W incandescent bulbs with 10W LED equivalents saves about $12 per month (at 5 hours/day and $0.16/kWh). That adds up to $144 per year from lighting alone. Switching every bulb in a typical home from incandescent to LED can cut lighting costs from roughly $15 per month to under $4.
Adjust Thermostat Settings
The Department of Energy recommends setting your thermostat to 78 degrees F in summer and 68 degrees F in winter when you are home. Each degree of adjustment can change your heating or cooling bill by about 3%. A programmable or smart thermostat that adjusts automatically when you are away or sleeping can save $50 to $150 per year.
Use Appliances During Off-Peak Hours
Some utilities offer time-of-use (TOU) pricing where electricity costs less during off-peak hours (typically nights and weekends). Running your dishwasher, washing machine, and dryer during off-peak periods can reduce the per-kWh cost for those loads. Check with your utility to see if TOU rates are available in your area.
Unplug or Use Smart Power Strips
Smart power strips automatically cut power to devices in standby mode. Plugging your entertainment center, home office equipment, or kitchen appliances into a smart strip can eliminate phantom loads and save $100 or more per year without changing your habits.
Understanding Your Electricity Bill
Your electricity bill contains several charges beyond the per-kWh energy rate. Understanding each line item helps you identify where your money goes and which charges you can influence.
Key Charges on Your Bill
Energy charge is the per-kWh rate multiplied by your total consumption. This is the portion you can reduce by using less electricity or shifting to off-peak hours. Delivery or distribution charge covers the cost of maintaining power lines and infrastructure. It is usually a fixed monthly fee plus a per-kWh component. Demand charge (common on commercial accounts) is based on your highest rate of electricity use during the billing period, measured in kilowatts.
Additional fees may include renewable energy surcharges, fuel adjustment charges, and state or local taxes. These vary by utility and location. The total of all charges divided by your total kWh gives your effective rate, which is typically 20% to 40% higher than the advertised energy rate alone. Use the percentage calculator to figure the markup between your advertised rate and effective rate.
Electricity Rates by State
Electricity rates vary dramatically across the United States. The table below shows a sample of states to illustrate the range. For the most current rates, visit the EIA Electric Power Monthly report.
| State | Avg. Rate ($/kWh) | Relative Cost |
|---|---|---|
| Louisiana | $0.11 | Below average |
| Idaho | $0.11 | Below average |
| Texas | $0.14 | Below average |
| Florida | $0.15 | Near average |
| Ohio | $0.15 | Near average |
| US Average | $0.18 | Average |
| Colorado | $0.16 | Near average |
| New York | $0.23 | Above average |
| California | $0.29 | Well above average |
| Massachusetts | $0.29 | Well above average |
| Connecticut | $0.30 | Well above average |
| Hawaii | $0.39 | Highest in US |
Source: US Energy Information Administration, Electric Power Monthly (2025-2026 data)
The large disparity in rates means that the same appliance costs very different amounts to run in different states. A window AC unit drawing 1,400W for 8 hours per day costs about $26.88 per month in Louisiana ($0.11/kWh) but $131.04 in Hawaii ($0.39/kWh). If you are moving to a new state, use this calculator with local rates to estimate your future electricity budget. Use the cost per unit calculator to compare per-kWh costs across different utility plans.
This calculator provides estimates for informational purposes only. Actual electricity costs depend on your specific utility rate schedule, taxes, fees, and appliance efficiency. Consult your utility bill or provider for exact pricing. For official energy data, visit the US Energy Information Administration.