Knowing how much each appliance costs to run empowers you to make smarter choices—whether you're deciding which device to use, when to upgrade, or where to cut back. The formula is simple: wattage, hours, and your electricity rate. Here's how to apply it.
The Basic Formula
Electricity consumption is measured in kilowatt-hours (kWh). One kWh equals 1,000 watts running for one hour. To find the cost:
kWh = (Watts ÷ 1,000) × Hours
Cost = kWh × Rate (per kWh)
Example: A 1,500-watt space heater running 4 hours per day uses (1,500 ÷ 1,000) × 4 = 6 kWh per day. At $0.12 per kWh, that's $0.72 per day or about $22 per month.
Finding Your Appliance's Wattage
Wattage is usually printed on a nameplate on the appliance—often on the back, bottom, or inside the door. It may show "W" or "Watts." Some devices show a range (e.g., 300–500W) because power draw varies with settings. Use the higher number for worst-case estimates. The EnergyGuide label on major appliances shows estimated annual kWh, which you can divide by 365 for a daily average.
Estimating Hours of Use
This is where guesswork comes in. A TV might run 5 hours daily. A refrigerator runs 24 hours but only the compressor cycles—use 8–12 "equivalent" hours. A dryer might run 5 hours per week. Be realistic: track a typical week if you're unsure.
Finding Your Electricity Rate
Your rate is on your utility bill, usually expressed as $/kWh. It might be a single rate or vary by time of use. The national average is around $0.12–$0.14 per kWh, but rates vary from under $0.10 to over $0.30 depending on location.
Step-by-Step Example
- Appliance: Window AC unit, 1,000 watts
- Usage: 8 hours per day during summer
- Rate: $0.12 per kWh
- Daily kWh: (1,000 ÷ 1,000) × 8 = 8 kWh
- Daily cost: 8 × $0.12 = $0.96
- Monthly cost: $0.96 × 30 = $28.80
"The formula is universal: watts, hours, rate. Once you know those three numbers for any appliance, you can estimate its cost. ElectriBill's calculator does the math for you—just plug in the values."
Using ElectriBill's Calculator
Our free calculator automates this process. Add each appliance with its wattage and daily hours, enter your rate, and get instant daily, monthly, and annual estimates. You can add multiple appliances to see your total projected bill and identify your biggest energy users.