What Is the Electricity Cost Calculator?
This calculator estimates how much it costs to run any electrical appliance. By entering the device's power rating in watts, how many hours you use it each day, the number of days, and your electricity price per kilowatt-hour (kWh), you instantly see the total cost, the cost per day, and the energy consumed. It works with any currency and any electricity tariff worldwide.
How to Use It
Find the appliance's wattage on its label or in the manual (for example, a 100 W bulb or a 1500 W heater). Enter the typical hours of use per day, the number of days you want to estimate (30 for a month, 365 for a year), and your price per kWh from your electricity bill. The result updates with the full cost breakdown.
The Formula Explained
Electricity is billed by energy, measured in kilowatt-hours. Since power is given in watts, we divide by 1000 to convert to kilowatts. Multiplying by hours of use gives kWh, and multiplying by your unit price gives the cost:
$$\text{Cost} = \frac{\text{Power (W)}}{1000} \times \text{Hours/day} \times \text{Days} \times \text{Price/kWh}$$
Worked Example
Suppose a 1000 W space heater runs 5 hours a day for 30 days at a price of $0.15 per kWh. Energy per day = \((1000 \div 1000) \times 5 = 5\) kWh. Over 30 days that is 150 kWh. Total cost = $$150 \times 0.15 = \mathbf{\$22.50}$$ or $0.75 per day.
FAQ
Where do I find the wattage? Check the rating label on the device, the power supply, or the user manual. Amps \(\times\) volts also gives watts.
What price should I enter? Use the per-kWh rate on your electricity bill, including any standing or supply charges divided in if you want a fuller estimate.
Does it account for standby power? No — it assumes the appliance draws its rated power only during the hours you enter. For always-on standby loads, use 24 hours and the standby wattage.
