Air Conditioning Running Cost Calculator

See what your air conditioner costs to run per hour, per day and per cooling season from its power draw, daily hours and your electricity price.

Air conditioning can be the biggest line on a summer bill. Enter your unit's power draw, how many hours a day it runs and how long your cooling season lasts to see the cost per hour, per day and across the whole season.

How the math works

Cost is power (kW) × hours × price, extended across a season. Divide watts by 1,000, multiply by daily hours and price for the daily cost, then by the number of days in your cooling season.

Worked example: a 1,000 W unit running 6 h/day uses 6 kWh a day, costing about $1.02/day at $0.17/kWh, or roughly $92 over a 90-day season.

If your unit only lists BTU, estimate watts by dividing BTU/h by the EER (typically 8–12). A rough guide is about 1 kW per 10,000 BTU on efficient units.

Assumptions and limits

This assumes a steady average power. Real air conditioners cycle on and off, and inverter models vary their draw, so once a room reaches temperature the average is lower than the nameplate. Insulation, outdoor temperature, humidity and thermostat setting all change the result. Raising the thermostat a few degrees and using fans is one of the biggest levers on this number.

When this calculator helps most

Use this before a heatwave to budget a realistic cooling-season cost, or to compare running an existing unit against buying a more efficient one — enter the same hours and season length for both and compare the two totals side by side. It's also the fastest way to answer "is it cheaper to run one unit all day in one room, or two units for a few hours each" once you have a rough wattage for each.

Mistakes that throw off the estimate

The biggest one is treating the unit's nameplate power as a constant draw for the whole session. Inverter units in particular pull much less once a room reaches its set temperature and the compressor throttles back, so a raw watts × hours calculation using peak power can overstate a full day's cost noticeably. If you know your unit cycles a lot (small room, well insulated, mild target temperature), treat the number here as a ceiling rather than a precise figure, and lean on the air conditioner running-cost page for a duty-cycle-adjusted typical figure instead.

Portable, split or central — why the type matters

The three common types of home air conditioning sit at very different points on this calculator, and it's worth knowing which one you're pricing. A portable unit is the least efficient per unit of cooling — it exhausts hot air through a hose but also pulls some already-cooled room air out with it, so it works harder for the same result. A split (wall-mounted) unit is meaningfully more efficient and is the typical case this calculator's defaults assume. A central or multi-split system covering a whole home draws far more in absolute watts, but often cools more space per watt than running several small portable units to do the same job — size the wattage entered to the specific unit or system you're actually pricing, not a generic "air conditioner" figure.

What it costs in practice

Cost of a 120-day cooling season by unit power and hours per day, at $0.17/kWh.

Your own price and habits change these — the calculator above uses your numbers.

Frequently asked questions