How Much Does It Cost to Run? Electricity Cost Calculator Guide
Ever wonder how much that space heater, gaming PC, or air conditioner is adding to your electric bill? Calculating electricity cost is surprisingly simple once you know the formula. This guide shows you how to figure out the running cost of any electrical device.
The Electricity Cost Formula
The cost to run any electrical appliance depends on three things:
- Wattage: How much power the device uses (found on the label or in the manual).
- Hours of use: How long you run it per day, week, or month.
- Electricity rate: How much your utility charges per kilowatt-hour (kWh). The U.S. average is approximately $0.16 per kWh, but rates vary from $0.10 to $0.40+ depending on your state.
The formula is:
Cost = (Watts × Hours of Use) / 1,000 × Rate per kWh
Worked Example
How much does it cost to run a 1,500-watt space heater for 8 hours a day at $0.16/kWh?
- Daily cost: (1,500 × 8) / 1,000 × $0.16 = $1.92 per day
- Monthly cost (30 days): $1.92 × 30 = $57.60 per month
- Annual cost: $1.92 × 365 = $700.80 per year
That single space heater costs over $700 a year to run. Understanding these numbers helps you make smarter decisions about which appliances to use and for how long.
Common Appliance Costs
Here are approximate monthly costs for common household appliances (based on typical usage at $0.16/kWh):
- Refrigerator (400W, 24/7): approximately $35/month
- Central air conditioning (3,500W, 8 hrs/day): approximately $135/month
- Electric dryer (5,000W, 5 loads/week, 1 hr each): approximately $16/month
- Desktop computer (300W, 8 hrs/day): approximately $12/month
- LED light bulb (10W, 8 hrs/day): approximately $0.38/month
- Gaming PC (500W, 4 hrs/day): approximately $10/month
- Electric water heater (4,500W, 3 hrs/day): approximately $65/month
How to Find Your Appliance Wattage
- Check the label or nameplate on the back or bottom of the device. It usually lists watts (W) or amps (A) and volts (V).
- If only amps and volts are listed: Watts = Amps × Volts. A device drawing 5 amps on a 120-volt outlet uses 600 watts.
- Use a plug-in electricity meter (like a Kill-A-Watt device) for the most accurate real-world measurement.
- Check the manufacturer's specifications online for the exact model.
Tips to Reduce Electricity Costs
- Switch to LED lighting: LEDs use 75% less energy than incandescent bulbs and last 25 times longer.
- Use smart power strips: They eliminate phantom power draw from devices in standby mode, which can account for 5% to 10% of your electric bill.
- Maintain your HVAC: Clean filters and regular maintenance keep heating and cooling systems running efficiently.
- Upgrade old appliances: An ENERGY STAR refrigerator uses up to 40% less energy than older models.
- Adjust thermostat settings: Every degree of thermostat setback saves roughly 1% to 3% on heating and cooling costs.
Calculate Your Electricity Costs
Use our electricity cost calculator to compute the energy consumption and cost of any electrical device, or explore all our physics calculators. Knowing which appliances consume the most power empowers you to reduce your electric bill without sacrificing comfort.
Small changes add up. By understanding the true cost of running your appliances, you can make informed decisions that save hundreds of dollars each year on your electricity bill.