Electricity Cost Calculator

Understanding Your Electricity Costs

Electricity costs are determined by a simple formula: power consumption in watts multiplied by time in hours, divided by 1,000 to convert to kilowatt-hours (kWh), then multiplied by your rate per kWh. The formula is Cost = (Watts x Hours) / 1000 x Rate. While the math is straightforward, most people underestimate how much individual appliances contribute to their monthly bill because consumption happens invisibly across dozens of devices running at different times.

Heating and cooling appliances typically dominate household electricity costs. An air conditioner running at 1,500W for 8 hours a day costs roughly $1.92 per day at the US average rate of $0.16/kWh — that adds up to about $58 per month for a single unit. Space heaters consume similar wattage. Switching to energy-efficient models with higher SEER ratings or using programmable thermostats can reduce these costs by 20-30% without sacrificing comfort.

Appliances that run continuously, like refrigerators and freezers, accumulate significant costs despite relatively low wattage. A refrigerator uses around 150W but runs 24 hours a day, consuming 3.6 kWh daily. At typical US rates, that is about $0.58 per day or $17 per month. Newer Energy Star rated models can reduce this by 40% or more compared to older units. The compressor does not actually run continuously — it cycles on and off, so real consumption is often lower than the rated wattage suggests.

Standby power, sometimes called "vampire load", is the electricity devices consume when turned off but still plugged in. TVs, game consoles, phone chargers, and computers in sleep mode all draw small amounts of power continuously. While each device might use only 1-5 watts, a typical home has 20-40 devices on standby. This can add up to 5-10% of total household electricity consumption, or $50-100 per year. Smart power strips that cut power completely when devices are not in use can eliminate this waste.

This calculator also estimates CO2 emissions based on a global average of 0.42 kg of CO2 per kWh. Your actual emissions depend on how your electricity is generated. Households powered by renewable energy produce near-zero direct emissions, while those on coal-heavy grids produce significantly more. Understanding the carbon impact of your electricity use is the first step toward making more sustainable energy choices. All calculations run entirely in your browser — nothing is stored or transmitted.