Electricity Cost Calculator

Calculate exactly how much any device costs to run. Enter wattage, daily hours, and your electricity rate to see daily, monthly, and annual costs.

🧮

Enter your values and click Calculate

Every electrical device in your home — from a 60-watt light bulb to a 2,000-watt space heater — has a running cost that depends on three things: how many watts it draws, how many hours per day you run it, and what your utility charges per kilowatt-hour (kWh). A kilowatt-hour is the standard unit on your electricity bill: one kWh is consumed when a 1,000-watt device runs for one hour. This calculator converts device wattage and usage into kWh, then multiplies by your rate to show daily, monthly, and annual costs. It is useful for understanding which appliances drive your electric bill, comparing the cost of running different devices, identifying energy-hungry equipment worth replacing, and estimating the electricity cost of a new appliance before buying it. The US national average electricity rate is around $0.13/kWh, but rates vary widely by state — from $0.09/kWh in Louisiana to over $0.30/kWh in Hawaii and parts of California.

How It Works

The formula converts watts to kilowatt-hours, then multiplies by the electricity rate. Step 1 — Daily kWh = (watts ÷ 1000) × hours per day. Dividing by 1,000 converts watts to kilowatts; multiplying by hours gives kilowatt-hours. Step 2 — Daily cost = daily kWh × rate per kWh. Step 3 — Monthly cost = daily cost × days per month. Step 4 — Annual cost = daily cost × 365. As a worked example: a 100-watt light bulb running 8 hours a day at $0.13/kWh. Daily kWh = (100 ÷ 1000) × 8 = 0.8 kWh. Daily cost = 0.8 × $0.13 = $0.104. Monthly cost (30 days) = $3.12. Annual cost = $37.96. The monthly calculation uses your specified days-per-month input, while the annual figure always uses 365 days for consistency.

Examples

LED Light Bulb
A 10-watt LED bulb running 5 hours a day at the US average rate.
Result: Daily: $0.0065. Monthly: $0.20. Annual: $2.37.
Space Heater
A 1,500-watt electric space heater running 6 hours a day for a winter month.
Result: Daily: $1.17. Monthly: $35.10. Annual: $427.35.
Gaming PC
A 350-watt gaming PC running 4 hours a day at a higher electricity rate.
Result: Daily: $0.252. Monthly: $7.56. Annual: $91.98.

Frequently Asked Questions

How do I find the wattage of a device?
Check the label on the device itself — appliances, electronics, and power supplies typically list wattage on a sticker or plate on the back or bottom. It may be listed as 'W' (watts) or as amps and volts, in which case you can calculate watts as amps × volts. For devices with variable power draw (like laptops or refrigerators), the label shows maximum wattage. Actual running wattage is typically lower and can be measured precisely with a plug-in power meter like the Kill-A-Watt.
What is the average US electricity rate?
The US national average is approximately $0.13–$0.16 per kWh as of 2024, but rates vary significantly by state and utility. Louisiana, Oklahoma, and other energy-producing states tend to have rates below $0.11/kWh, while Hawaii ($0.30+), California ($0.25+), and Connecticut ($0.25+) have some of the highest rates. Check your electricity bill for the exact rate — it is usually listed as the 'energy charge' in cents per kWh.
Which household appliances use the most electricity?
The biggest electricity consumers in a typical US home are: central air conditioning (3,000–5,000W), electric water heaters (4,000–5,500W), electric clothes dryers (4,000–6,000W), and electric ranges (6,000–10,000W when in use). Space heaters (1,500W) and refrigerators (150–400W running average) are also significant contributors. Small electronics like phone chargers (5–20W) and LED bulbs (8–15W) have a negligible individual impact despite running continuously.
How do I reduce my electricity bill most effectively?
Focus on high-wattage devices that run many hours: water heaters, HVAC systems, and dryers. Switching to a heat pump water heater can cut water heating costs by 60–70%. Smart thermostats reduce HVAC runtime. Replacing old appliances with Energy Star models typically cuts their electricity use by 20–50%. For lighting, the switch to LED has already happened for most households — an LED uses 75% less power than the incandescent it replaces.

Related Calculators

finance💰

EV vs Gas

Compare the annual cost of driving an electric vehicle vs a gas car. Enter your miles, gas price, and electricity rate to see your real yearly savings.

Calculate →
finance💰

Solar Savings

Estimate how much money solar panels could save you on electricity bills.

Calculate →