Where do I find the wattage of my appliance?

Check the label on the back or bottom of the device, or look in the user manual. It is usually listed as "W" or "Watts". For variable devices like dimmer lights or inverter ACs, use the average wattage.

Where do I find my electricity rate?

Check your electricity bill — it is typically shown as a cost per kWh (kilowatt-hour). Rates vary by country and provider, but a common range is $0.10 to $0.35 per kWh.

Why does the monthly cost use 30.44 days?

A calendar month averages 30.44 days (365 / 12). This gives a more accurate monthly figure than using exactly 30 days.

Can I calculate costs for multiple appliances?

Yes — use the multi-appliance list in this tool. Add each appliance separately and the tool sums up the total cost.

Does this include standby or idle power?

No — only the hours you enter are counted. To include standby power, add the standby wattage as a separate appliance running 24 hours a day.

How do I convert watts to kWh?

Multiply watts by hours of use, then divide by 1,000. For example, a 1,500 W heater run for 3 hours uses 1,500 × 3 / 1,000 = 4.5 kWh. At $0.15/kWh that costs about $0.68 per day.

Energy Cost Calculator

Name: Energy Cost Calculator
Availability: InStock
Author: Nham Vu

Enter appliance wattage, daily usage hours, and your electricity rate to see daily, monthly, and annual electricity costs.

Appliance Details

Appliance Wattage (W)

Check the label on the device or manual.

Hours of Use per Day

Electricity Rate ($/kWh)

Find this on your electricity bill.

Label (optional)

Common Appliances

Enter appliance details on the left and click Add to List.

Done!

Summary

Enter appliance wattage, daily usage hours, and your electricity rate to see daily, monthly, and annual electricity costs.

How it works

Enter the appliance wattage (W) from its label or manual.
Enter how many hours per day you run it.
Enter your electricity rate in $/kWh from your bill.
The tool converts watts to kilowatts (kW = W / 1000) and multiplies by daily hours for daily kWh consumption.
Daily kWh times your rate gives daily cost; monthly uses 30.44 days and annual uses 365 days.

Use cases

Estimate the running cost of an air conditioner, heater, or refrigerator.
Compare energy costs of different appliances before purchasing.
Calculate how much a gaming PC, TV, or home office setup costs per year.
Identify which appliances are driving up your electricity bill.
Plan energy budgets for rental properties or small businesses.

Frequently Asked Questions

Last updated: 2026-06-10 · Reviewed by Nham Vu