Electricity Cost Calculator
Calculate electricity cost based on watts and hours.
Daily cost
$0.10
Monthly cost
$2.88
Annual cost
$35.04
0.800 kWh consumed per day
How to use Electricity Cost Calculator
Enter Power Consumption in Watts
Locate the 'Power (Watts)' input field at the top of the calculator. Type the wattage of your device or appliance. For example, enter 1000 for a 1000-watt microwave or 60 for a standard light bulb. You can find wattage on device labels or manuals.
Input Usage Hours
Click on the 'Hours of Use' field and enter how many hours per day, per month, or per year the device runs. Enter decimal values if needed (e.g., 2.5 hours). The calculator accepts any time period you specify.
Set Your Electricity Rate
Enter your local electricity rate in the 'Cost per kWh' field. Find this rate on your utility bill (usually $0.10-$0.20 per kilowatt-hour in the US). Leave default if unsure, then adjust for your region.
View Instant Results
Click the 'Calculate' button to see your total electricity cost displayed immediately below the form. Results show cost breakdowns for different time periods and daily, monthly, and yearly estimates.
Reset or Modify Values
Click 'Reset' to clear all fields and start a new calculation. Modify any input field and recalculate to compare costs for different devices or usage patterns.
Related Tools
Electricity cost calculator: find out what any appliance costs to run
Electricity cost calculator: find out what any appliance costs to run
Wondering what your electric space heater is really adding to your bill? Use the free electricity cost calculator on ToolHQ to find out exactly how much any appliance costs per day, per month, and per year.
An electricity cost calculator converts an appliance's wattage and your daily usage hours into a real dollar amount, using your local electricity rate. The result tells you not just a vague estimate but the specific annual cost of keeping that device plugged in.
Most people have no idea what runs their electricity bill up. Is it leaving lights on? The refrigerator? The gaming PC that never gets fully shut down? ToolHQ's electricity cost calculator shows daily, monthly, and annual costs all at once, and includes average kWh rates by country so you have a starting point even if you have not checked your last bill.
Key Takeaways
- Electricity cost = (Watts × Hours per day / 1,000) × Rate per kWh
- The average US electricity rate is about 16 cents per kWh (EIA, 2024)
- An electric space heater (1,500W) running 8 hours per day costs roughly $52 per month at US average rates
- Standby power (phantom load) from idle devices can account for 5-10% of a home's electricity bill
- No data is stored or transmitted, all calculations run in your browser
How electricity costs are calculated
The formula has three parts: power (watts), time (hours), and price (cents or dollars per kWh).
Step 1: Convert watts to kilowatts. Divide the wattage by 1,000. A 1,500-watt heater = 1.5 kW.
Step 2: Calculate daily energy use in kWh. Multiply kilowatts by daily usage hours. Running a 1,500W heater for 6 hours: 1.5 kW × 6 hours = 9 kWh per day.
Step 3: Multiply by your electricity rate. Multiply kWh by cost per kWh. At $0.16/kWh: 9 kWh × $0.16 = $1.44 per day.
Step 4: Project forward. $1.44/day × 30 = $43.20/month. × 365 = $525.60/year.
The full formula is: Cost = (Watts × Hours / 1,000) × Rate
According to the U. S. Energy Information Administration, the average US residential electricity rate is about 16.2 cents per kWh as of recent data, though rates vary significantly by state, from under 10 cents in parts of the South to over 30 cents in Hawaii and California. According to Wikipedia's kilowatt-hour article, a kilowatt-hour is the unit of energy consumed when a 1,000-watt device runs for one hour, which is the standard unit used by electric utilities worldwide.
When the electricity cost calculator is most useful
This tool answers a few different questions depending on your situation.
Identifying your biggest cost drivers. Most people are surprised to find that heating and cooling (HVAC) is by far the largest home electricity consumer, typically 45-50% of a home energy bill. After HVAC, water heaters, refrigerators, washer/dryers, and lighting are the next biggest contributors.
Comparing appliances before buying. A 60W LED TV uses about $8 per year. A 300W plasma TV from ten years ago costs about $40 per year in the same number of hours. If you are replacing an old appliance, the electricity cost calculator quantifies the annual savings from upgrading to a more efficient model.
Making the case for behavior changes. Turning off a device sounds like a small act. Seeing that leaving a gaming PC running 24/7 at 300W costs $420 per year makes the decision concrete.
Take Jordan, a college student who was shocked when his apartment's electricity bill jumped $65 in a single month. He had started using a 1,500-watt space heater in his room instead of turning on the building's shared HVAC. He entered 1,500 watts, 10 hours per day, and $0.18 per kWh (his local rate) into the calculator. The result: $81 per month. That matched almost perfectly. He switched to layering clothing and a heated blanket instead, dropping his bill back down by $55.
Calculate your appliance's cost now
How to use the ToolHQ electricity cost calculator
Four inputs, instant results.
- Enter the wattage. Find this on the appliance itself, its power cable, or its manual. It may be listed as "1500W" or "1.5kW." If listed in kW, multiply by 1,000 to get watts.
- Enter hours per day. How many hours per day do you actually use this device? Be honest. A TV you leave on as background noise might run 8+ hours.
- Enter your electricity rate (kWh rate). Check your most recent electricity bill for the "rate" or "cost per kWh." If you cannot find it, you can use the country average from the table below.
- Read the results. The calculator shows your daily, monthly, and annual cost instantly.
No data is stored or transmitted. All calculations run in your browser.
Wattage reference table and electricity rates by country
Common appliance wattage and annual running cost
This table uses $0.16/kWh (US average) and assumes typical daily usage.
| Appliance | Typical wattage | Assumed daily use | Monthly cost | Annual cost |
|---|---|---|---|---|
| Electric space heater | 1,500W | 6 hours | $43 | $526 |
| Central air conditioner | 3,500W | 6 hours (summer) | $100 | $1,210* |
| Electric water heater | 4,000W | 3 hours | $58 | $701 |
| Clothes dryer | 5,000W | 45 min/day avg | $36 | $438 |
| Refrigerator (modern) | 150W | 24 hours | $17 | $210 |
| Desktop PC + monitor | 300W | 8 hours | $18 | $210 |
| Gaming PC (under load) | 600W | 5 hours | $14 | $175 |
| LED TV (55 inch) | 70W | 5 hours | $2 | $20 |
| LED light bulb | 10W | 8 hours | $0.38 | $4.67 |
| Microwave | 1,200W | 15 min/day | $1.44 | $17 |
| Dishwasher | 1,800W | 1 hour/day | $8.64 | $105 |
| Washing machine | 500W | 1 hour/day | $2.40 | $29 |
| Laptop | 50W | 8 hours | $1.92 | $23 |
| Phone charger | 5W | 8 hours | $0.19 | $2.34 |
| Smart TV on standby | 1-2W | 24 hours | $0.23 | $2.81 |
*Air conditioner cost estimated for summer months only; full-year average is lower.
Average electricity rates by country
| Country | Average rate (residential) | Currency per kWh |
|---|---|---|
| United States | ~16.2 cents | USD/kWh |
| United Kingdom | ~24 pence | GBP/kWh |
| Germany | ~31 euro cents | EUR/kWh |
| France | ~19 euro cents | EUR/kWh |
| Australia | ~28-33 cents | AUD/kWh |
| Canada | ~12-17 cents | CAD/kWh |
| India | ~8-10 rupees | INR/kWh |
These are average residential rates. Business rates and time-of-use tariffs vary. Check your bill for the exact rate.
The phantom load problem
Many devices draw power even when switched off or on standby. A gaming console on standby: 1-2W. A cable box: 15-17W continuously. A desktop PC in sleep mode: 5-10W. A collection of six or seven such devices can add 40-80W of constant draw, or 30-60 kWh per month, costing $5-$10 per month for nothing useful. Plugging them into a power strip and switching it off when not in use eliminates the phantom load entirely.
Claire, a remote worker running a home office, started calculating the cost of every device on her desk. Her monitor (45W), desktop PC (280W), desk lamp (12W), router (15W), and printer in standby (8W) added up to 360W of average draw across a 10-hour workday. Annual cost at $0.15/kWh: roughly $197 per year just for her home office setup. She switched to a more efficient laptop and cut that number by 60%.
For related tools, the fuel cost calculator helps with transport energy costs, and the unit converter can convert between energy units if your appliance lists power in horsepower or BTU.
Frequently asked questions
How do I find the wattage of my appliance?
Check the label on the appliance itself, often on the bottom, back, or near the power cord. It may say "1500W" or "1.5 kW" or list amps and volts separately (multiply amps × volts = watts). The product manual or manufacturer's website also lists power consumption specs.
What is a kilowatt-hour?
A kilowatt-hour (kWh) is the energy used when a 1,000-watt device runs for one hour. Your electricity bill charges you per kWh. A 100-watt lightbulb running for 10 hours uses 1 kWh.
What is the average US electricity rate?
Around 16 cents per kWh for residential customers nationally, but it ranges from under 10 cents in some Southern states to over 30 cents per kWh in Hawaii and California. Check your electricity bill for the exact rate you pay.
Does leaving devices on standby waste much electricity?
Yes. Standby power (called phantom load) can account for 5-10% of a home's electricity bill. Devices like cable boxes, game consoles, and desktop computers draw watts continuously even when not actively used.
How much does it cost to run a 1,500-watt space heater all day?
At 16 cents per kWh, a 1,500W heater running 24 hours costs 1.5 kW × 24 hours × $0.16 = $5.76 per day. That is $172.80 per month. Running it for 8 hours per day costs about $57.60 per month.
The short version
Electricity costs are invisible until you calculate them. An appliance you barely think about can quietly add $50, $100, or $500 to your annual bill. ToolHQ's electricity cost calculator takes your wattage, daily use, and local rate and gives you the daily, monthly, and annual cost in one view, with no account needed and no data stored.
Try the free electricity cost calculator now
If you are comparing the long-term cost of gas versus electric appliances, the fuel cost calculator covers the gas side of the equation. For broader energy budgeting, the budget planner helps you track utility costs alongside your other expenses.