Electricity Bill Calculator — Estimate Your Monthly Power Cost

How Electricity Billing Works

Electricity is measured in kilowatt-hours (kWh). One kWh = 1,000 watts of power running for one hour. Your electricity bill charges you per kWh consumed. The formula is:

kWh = (Watts / 1000) × Hours per day × Days

Then: Cost = kWh × rate per kWh. The US average residential rate is roughly $0.13–$0.17/kWh, but it varies significantly by state.

How to Use the Calculator

1. Open the electricity bill calculator.
2. Set your rate per kWh — find this on your electricity bill under "Energy Charge."
3. Set the number of days in the billing period (30 for monthly, 7 for weekly).
4. For each appliance, enter its name, watts, and hours per day.
5. Add rows as needed with the "+ Add Appliance" button.
6. The table shows kWh and cost per appliance; the summary shows your total estimated bill.

Typical Appliance Wattages

Finding Your Appliance Wattage

Check the label on the back or bottom of the appliance — most list wattage directly. If it shows amps and volts but not watts, multiply them: W = V × A. In the US, most household circuits run at 120V; large appliances (dryers, ovens, EV chargers) use 240V.

Advanced Workflows

Finding the biggest cost drivers

Enter all your appliances and sort by monthly cost. In most homes, the top three are heating/cooling (HVAC), water heating, and laundry. Target these first for meaningful savings — replacing a 60W incandescent with a 10W LED saves about $3/year per bulb, but reducing AC runtime by one hour per day saves much more.

Calculating standby power

Many devices draw power even when "off." A game console on standby uses 1–10W continuously. Add standby devices with their estimated wattage at 24 hours/day to see their annual cost. Collectively, standby devices can account for 5–10% of a home's electricity bill.

Modelling an EV charger

A Level 2 EV charger runs at 7,200W and might charge for 4 hours nightly. That is 7.2 kW × 4 h = 28.8 kWh per night × 30 days = 864 kWh/month — adding roughly $112/month at $0.13/kWh. Enter this as a single appliance row to see its impact.

Common Questions

Why does my actual bill differ from the estimate?

Utility bills include fixed charges, distribution fees, and taxes beyond the raw energy cost. Also, appliance wattage varies with usage: an AC compressor cycles on and off, so its effective wattage is lower than its peak rating. Treat the estimate as a guide, not a prediction.

How do I find my electricity rate?

Look at your utility bill. Find the line labelled "Energy Charge" or "kWh Rate." It is usually listed as cents per kWh (e.g., 13.2¢/kWh = $0.132). The bill may also show a tiered rate if you are charged differently above a certain usage threshold.