Cost to run central air conditioning per day and month

What central air conditioning costs

At 17 cents a kilowatt hour, central air conditioning costs 59.5 cents an hour while it is drawing power. 6 hours a day with 50 percent average draw is 10.50 kWh a day, $53.55 a month and $651.52 a year. Change any of those three numbers in the calculator and the answer moves with them, because there is nothing else in the sum.

The label figure is 3500 watts. That is what the device draws while it is working, not what it draws around the clock.

Hours of use a day	Energy a day	Cost a month	Cost a year
1 h	1.75 kWh	$8.93	$108.59
2 h	3.50 kWh	$17.85	$217.17
4 h	7.00 kWh	$35.70	$434.35
6 h	10.50 kWh	$53.55	$651.52
8 h	14.00 kWh	$71.40	$868.70

What changes the number

• The number is the outdoor condenser, which is the large load. The air handler inside adds 300 to 500 W while the fan runs.
• Efficiency is sold as SEER2. Going from a 14 SEER2 unit to a 16 SEER2 unit cuts running cost roughly 12 percent for the same cooling; the arithmetic is that simple and that small.
• In a hot climate the duty cycle sits near 100 percent in the afternoon and near zero at night, so a monthly average is more honest than one day's reading.

Find your own wattage

The rating plate on the outdoor unit gives the maximum circuit amps and the rated load amps. Rated load amps multiplied by 240 volts is close to the running draw.

What this does not include

It assumes the ducts are sealed and insulated. Leaky ducts in an attic can waste a fifth of the cooling before it reaches a room.

Check it against your own numbers

The [running cost calculator](../index.html?device=central-ac) opens with this device already selected and its wattage filled in. Replace the wattage with your own reading, set the hours you actually use, and the monthly and yearly figures update in place.

Related: [A 1,500 W space heater](../space-heater/index.html), [An electric blanket](../electric-blanket/index.html), [A dehumidifier](../dehumidifier/index.html).