Electricity Cost Calculator

How to Use This Electricity Cost Calculator

This electricity cost calculator helps you estimate how much it costs to run any electrical appliance or device. By entering the wattage, daily usage hours, your electricity rate, and the number of units, you can see the daily, monthly, and yearly cost in seconds. This is useful for budgeting, comparing appliance efficiency, and identifying which devices are driving up your electricity bill.

Steps to calculate electricity costs:

1. Enter the wattage of your appliance (look for the label on the back or bottom, or check the manual). You can also click a quick preset button for common appliances.
2. Enter how many hours per day the appliance runs on average.
3. Enter your electricity rate in dollars per kilowatt-hour (kWh). The US average is around $0.15/kWh, but check your bill for your exact rate.
4. If you have multiple identical appliances (for example, several light bulbs), enter the number of units.
5. The calculator instantly shows your energy consumption and cost for daily, monthly (30-day), and yearly periods.

Understanding Electricity Costs

Your electricity bill is determined by two main factors: how much electricity you use (measured in kilowatt-hours, or kWh) and the rate you pay per kWh. Understanding these two factors is the key to managing and reducing your energy costs.

What is a kilowatt-hour (kWh)?A kilowatt-hour is the standard unit of energy consumption on your electricity bill. One kWh equals using 1,000 watts (1 kilowatt) of power for one hour. For example, running a 1,000-watt microwave for one hour uses exactly 1 kWh. Running a 100-watt light bulb for 10 hours also uses 1 kWh. It is a measure of energy, not power — power is the rate at which energy is used, while energy is the total amount consumed over time.

Electricity rates vary widely. The average residential electricity rate in the United States is approximately $0.15 per kWh (as of 2025), but actual rates range from under $0.08 per kWh in states like Louisiana and Washington to over $0.30 per kWh in Hawaii and Connecticut. Rates also depend on your utility provider, the time of day (time-of-use pricing), the season, and whether you are on a fixed-rate or variable-rate plan.

Fixed charges vs. consumption charges: Your electricity bill typically includes both a fixed monthly charge (just for being connected to the grid) and a variable charge based on your kWh consumption. The consumption charge is what this calculator estimates. Some bills also include demand charges, taxes, surcharges, and fees for renewable energy programs. To find your effective rate, divide your total bill amount by the total kWh consumed.

How to Calculate kWh

The formula for calculating kilowatt-hours from watts and hours is straightforward:

kWh = (Watts × Hours per Day × Number of Units) / 1000

Example 1:A 1,500-watt window air conditioner running 8 hours per day: kWh = (1500 × 8) / 1000 = 12 kWh per day. At $0.15/kWh, that is $1.80 per day, $54.00 per month, and $657.00 per year.

Example 2:Ten 10-watt LED bulbs running 6 hours per day: kWh = (10 × 6 × 10) / 1000 = 0.6 kWh per day. At $0.15/kWh, that is $0.09 per day, $2.70 per month, and $32.85 per year.

Finding your appliance's wattage:Most appliances have a label (often on the back, bottom, or inside the door) that shows the wattage or amperage. If the label shows amps and volts instead of watts, you can calculate watts as: Watts = Amps × Volts. Standard US outlets are 120 volts. For large appliances like electric dryers or ovens that use 240 volts, use 240 in the calculation.

Estimated vs. actual wattage: The wattage on the label is typically the maximum power draw. Many appliances cycle on and off during operation. For example, a refrigerator labeled at 150 watts may only actually run its compressor about one-third of the time, making its average consumption closer to 50 watts. For cycling appliances, the yearly energy usage (in kWh/year) on the EnergyGuide label is often more accurate than calculating from the listed wattage.

Common Appliance Costs Reference

The following table shows estimated monthly and yearly costs for common household appliances, assuming an electricity rate of $0.15/kWh. These are approximate figures based on typical usage patterns.

Keep in mind:Actual costs will vary based on your local electricity rate, the age and efficiency of your specific appliances, and your usage habits. Newer ENERGY STAR certified appliances typically use 10–50% less energy than standard models.

Tips to Reduce Electricity Bills

Lowering your electricity consumption not only saves money but also reduces your carbon footprint. Here are effective strategies that can cut your energy bill significantly.

• Switch to LED lighting. LED bulbs use about 75% less energy than incandescent bulbs and last 25 times longer. Replacing just five frequently used bulbs with LEDs can save $75 per year on lighting costs.
• Unplug vampire loads.Many devices draw power even when turned off (known as phantom or vampire loads). TVs, chargers, gaming consoles, and computers in standby mode can add $100–200 per year to your bill. Use smart power strips that cut power completely when devices are in standby.
• Adjust your thermostat.Heating and cooling account for about 50% of home energy use. Set your thermostat to 68°F (20°C) in winter and 78°F (26°C) in summer. Each degree you adjust can save 3–5% on heating and cooling costs. A programmable or smart thermostat can automate these adjustments.
• Use appliances efficiently. Run your dishwasher and washing machine with full loads only. Air-dry clothes when possible instead of using the dryer. Cook with smaller appliances (microwave, slow cooker, air fryer) instead of the full oven for small meals.
• Improve insulation and sealing.Proper insulation in your attic and walls, weatherstripping around doors and windows, and sealing duct leaks can reduce heating and cooling costs by 10–20%.
• Upgrade to ENERGY STAR appliances. When it is time to replace an old appliance, look for the ENERGY STAR label. ENERGY STAR certified refrigerators use 15% less energy than non-certified models, and certified washers use 25% less energy.
• Use off-peak electricity.If your utility offers time-of-use pricing, shift heavy electricity use (laundry, dishwasher, EV charging) to off-peak hours when rates are lower. This can save 10–30% on your bill depending on your plan.

Frequently Asked Questions

How do I find my electricity rate?

Look at your monthly electricity bill from your utility company. Find the section that shows your total kWh consumption and the total charges. Divide the total charges by the total kWh to get your effective rate per kWh. Be aware that some bills include tiered rates (where the price changes based on how much you use) or time-of-use rates (where the price varies by time of day). In those cases, use an average rate for estimation purposes.

What is the difference between watts and kilowatt-hours?

Watts (W) measure power — the rate at which an appliance uses energy at any given moment. Kilowatt-hours (kWh) measure energy — the total amount of electricity consumed over time. Think of it like speed and distance: watts are like miles per hour, and kilowatt-hours are like total miles traveled. A 1,000-watt appliance running for one hour uses one kilowatt-hour of energy.

Does an appliance use electricity when turned off?

Many modern appliances draw a small amount of standby power even when switched off. This is called phantom load or vampire power. Common culprits include TVs, cable boxes, gaming consoles, computers in sleep mode, chargers left plugged in, and smart appliances. A single device might only use 1–5 watts in standby, but the combined phantom load of all your devices can add 5–10% to your total electricity bill. Using smart power strips can eliminate most of this waste.

How much does it cost to run a space heater?

Most space heaters use 1,500 watts. Running one 8 hours per day at $0.15/kWh costs about $1.80 per day, $54 per month, or $657 per year. Space heaters are one of the most expensive appliances to run per unit of heat produced. For sustained heating, a central heating system or heat pump is typically more cost-effective.

Is it cheaper to run appliances at night?

It depends on your electricity plan. If you have a time-of-use (TOU) rate plan, electricity is typically cheaper during off-peak hours (usually 9 PM to 7 AM on weekdays and all day on weekends). If you are on a flat-rate plan, the time of day does not affect your cost. Check with your utility company to find out what rate plan you have and when off-peak hours occur.

How accurate is this calculator?

The calculator provides estimates based on the inputs you provide. Its accuracy depends on how closely your inputs match actual usage. The wattage you enter may differ from the appliance's actual average power draw (especially for cycling appliances like refrigerators and air conditioners). For the most accurate estimates, use the annual kWh consumption from the EnergyGuide label and divide by 365 to get the daily average.

Does the number of units affect the per-unit cost?

No. The cost scales linearly with the number of units. If one light bulb costs $4.38 per year, ten identical bulbs will cost $43.80 per year. However, some utilities offer tiered pricing where the per-kWh rate increases as you consume more electricity, which would make additional units slightly more expensive at higher consumption levels.