Estimate how much your air conditioner adds to your electricity bill based on its power rating, daily runtime, and your local rate.
Your air conditioner's running cost depends on how much power it draws (in watts), how many hours a day you run it, and the price your utility charges per kilowatt-hour. Multiplying these together converts your AC's usage into a dollar figure you can compare against your utility bill.
Daily kWh = (Watts ÷ 1000) × Hours per Day
Daily Cost = Daily kWh × Electricity Rate
Monthly Cost = Daily Cost × Days Run per Month
Annual Cost = Monthly Cost × 12
Check your AC unit's nameplate or manual for its wattage (or convert from BTU by dividing by about 3.4). Enter how many hours a day you typically run it, your electricity rate from your utility bill, and how many days a month it runs.
A 1,500-watt window AC unit run 8 hours a day uses 12 kWh daily. At $0.16 per kWh, that's about $1.92 a day, roughly $57.60 a month if run every day, and around $691 a year if used year-round at that schedule.
It multiplies your AC's power draw (watts) by the hours you run it per day and your local electricity rate, converting watt-hours to kilowatt-hours (kWh) for billing.
Check the unit's nameplate/label or manual for its rated power in watts, or use the BTU rating: roughly divide BTU by 10 to estimate watts for a rough figure.
No, it estimates active cooling cost only. Standby/idle draw is usually small enough to ignore for a household running-cost estimate.