How Much Electricity Does an AC Use? Cost Breakdown by Type (2026)

Window AC Electricity Usage by BTU Size

Window air conditioners are the most common single-room cooling solution. Their electricity consumption depends on two factors: BTU capacity (the amount of cooling they deliver) and EER (Energy Efficiency Ratio — the cooling output per watt of electricity consumed). The formula is simple:

Modern window ACs carry EER ratings of 10–12 for standard models and up to 15 for premium ENERGY STAR models. The DOE minimum for window units is 10.3 EER for units under 8,000 BTU. Here is the complete breakdown at a 10 EER baseline:

Real-world consumption is lower than these maximums because window ACs cycle on and off rather than running continuously at full capacity. An AC running at 70% duty cycle (typical in moderate climates) uses 30% less electricity than the maximums shown. In a hot Southern climate with 95°F+ outdoor temperatures, duty cycles can approach 90–100% during peak afternoon hours. Use our Appliance Cost Calculator to model duty cycle and local electricity rates for your specific unit.

Window ACs size by room square footage: 5,000 BTU handles 100–150 sq ft; 8,000 BTU handles 200–300 sq ft; 12,000 BTU handles 400–550 sq ft. Oversizing — a common mistake — increases electricity use without improving comfort, because oversized units cycle rapidly and fail to dehumidify properly.

Central AC Electricity Usage by Tonnage

Central air conditioning is rated in tons: 1 ton = 12,000 BTU/hour of cooling capacity. A 2,000 sq ft home typically requires a 2.5–3.5 ton system depending on climate, insulation, window area, and ceiling height. The electricity consumption depends heavily on SEER2 rating (see Section 5). Here is the breakdown for the most common unit sizes at both minimum-standard and high-efficiency ratings:

The kWh/hour figures above are calculated as BTU ÷ (SEER2 × 1,000). Note that central ACs rarely run at 100% duty cycle except during heat waves. In a temperate climate with an average summer temperature around 80°F, a properly-sized central AC may run at 50–70% duty cycle, reducing actual monthly consumption by 30–50% below these figures. In Phoenix, Arizona or Miami, Florida during July, duty cycles approach 90%+ during afternoon hours.

Duct losses are a hidden cost that these figures do not fully capture. The EIA estimates that duct losses in typical homes waste 20–30% of the cooled air before it reaches living spaces. A central AC running on 14 SEER2 with 25% duct losses effectively delivers only about 10.5 SEER2 of useful cooling to the rooms. Mini-splits eliminate this waste entirely. Calculate what your central AC actually costs with our Electricity Cost Calculator.

Portable AC: The Most Expensive Option

Portable air conditioners are popular because they require no installation — you just wheel them in, stick the exhaust hose out a window, and plug them in. They are also, per BTU of cooling delivered, the most expensive type to run. Here is why, and by how much.

A portable AC exhausts warm air through a hose — but that warm air has to come from somewhere. As the unit exhaust warm air out the window, it creates negative pressure in the room, which draws unconditioned (warm, humid) air in through door gaps, window cracks, and other building penetrations. The AC then has to cool that infiltration air on top of the intended load. This “infiltration penalty” can reduce effective efficiency by 30–50% compared to the unit’s rated specifications.

A comparison of typical units at the same BTU capacity (8,000 BTU):

The DOE introduced the SACC (Seasonally Adjusted Cooling Capacity) standard in 2017 to account for the infiltration penalty in portable AC ratings. An older portable AC rated at 12,000 BTU under the old standard may carry only 6,000–7,000 BTU SACC. Always compare SACC ratings when evaluating portable units. Dual-hose models (one hose for exhaust, one for intake) reduce — but do not eliminate — the infiltration problem.

If you have any window that can accommodate a window unit, use a window AC. The electricity cost difference over a summer (3 months) for an 8,000 BTU application is approximately $40–$80 in favor of the window unit. Over five years, that is $200–$400 in unnecessary electricity costs.

Mini-Splits: The Efficiency Leader

Ductless mini-split systems are the most efficient way to cool and heat your home. They consist of an outdoor compressor unit connected to one or more indoor air handlers via refrigerant lines — no ducts required. Their electricity efficiency advantage comes from two sources: elimination of duct losses and variable-speed (inverter) compressor technology.

Duct loss elimination: Central AC systems lose 20–30% of their cooled air through duct leakage, conduction through duct walls, and poor distribution. A 3-ton central AC at 14 SEER2 effectively delivers only about 10–11 SEER2 of useful cooling to the rooms due to these losses. A mini-split with direct indoor air handlers delivers close to its rated efficiency.

Inverter compressor technology: Standard central AC systems use single-speed or two-speed compressors that cycle fully on and fully off. Inverter-driven mini-split compressors modulate their output speed continuously to match the exact cooling load. At 60% load, the compressor runs at 60% speed rather than cycling on and off. This reduces electricity consumption and eliminates the temperature swings associated with on/off cycling.

The best-in-class mini-splits from Mitsubishi, Daikin, and Fujitsu reach SEER2 ratings of 24–28+, which represents 60–70% less electricity consumed per BTU compared to a minimum-standard central AC at 14 SEER2. Over a 3-month cooling season in a hot climate, the difference between a 14 SEER2 central system and a 24 SEER2 mini-split for a 2,000 sq ft home is approximately $450–$600 in electricity costs.

Mini-splits also function as heat pumps in winter, providing highly efficient heating alongside cooling. This dual functionality — especially in climate zones 2–5 — makes them a strong candidate for whole-home electrification. Explore how mini-splits fit into a complete home energy strategy with our Home Electrification Planner.

SEER2 Explained: How It Affects Your Electric Bill

SEER2 — Seasonal Energy Efficiency Ratio 2 — replaced the original SEER standard on January 1, 2023. The “2” denotes a new DOE test procedure (M1) that increases external static pressure by five times to better simulate real-world ductwork resistance. This means SEER2 ratings are typically 4–7% lower than the old SEER ratings for identical equipment. A unit rated 15 SEER would score approximately 14.3 SEER2.

The DOE mandated new minimum standards effective January 1, 2023: 13.4 SEER2 for the North; 14.3 SEER2 for the Southeast and Southwest for units under 45,000 BTU; 13.8 SEER2 for units 45,000 BTU and above in those regions; and 14.3 SEER2 for heat pumps nationally.

Annual hours assume 750 cooling hours — representative of a moderate climate like Dallas, TX or Atlanta, GA. Hot climates like Miami or Phoenix may see 1,400–1,800 annual cooling hours, multiplying the cost differential between SEER2 ratings proportionally. The savings from upgrading from 14 SEER2 to 21 SEER2 in a hot climate with 1,500 annual cooling hours: approximately $259/year for a 3-ton system at national average electricity rates.

Higher SEER2 systems cost more upfront — typically $300–$1,200 more for a 3-ton central unit at 18–21 SEER2 vs. 14 SEER2. At $150–$260/year in operating savings, the payback on the efficiency premium is 2–5 years. After payback, the savings continue for the remaining 12–15 years of the system’s life. Calculate total cost of ownership for any AC upgrade with our Appliance Cost Calculator.

Monthly AC Cost by State and Region

Your monthly AC bill depends on two independent variables that vary dramatically by location: electricity rate and cooling hours. A homeowner in Louisiana pays $0.124/kWh (among the cheapest in the U.S.) but may run their AC 2,000+ hours per summer. A homeowner in Hawaii pays $0.42/kWh but may only need light cooling. Here is the monthly cost for a 3-ton, 14 SEER2 central AC running 10 hours/day:

Electricity rate data from Electric Choice and EIA (March 2026). These are the monthly costs at peak summer usage. In states like Florida, Texas, and Louisiana, AC runs 8–12 hours/day for 4–6 months of the year, meaning annual cooling costs of $950–$2,800 depending on system size and efficiency.

High electricity rate states like California and New England have the strongest financial case for upgrading to high-efficiency systems, since every percentage point of efficiency improvement translates to larger dollar savings at $0.28–$0.30/kWh vs $0.12/kWh. Calculate your specific state cost with our Solar Savings calculator — solar can offset AC electricity costs significantly in sunny states.

Full AC Type Comparison

Here is a consolidated comparison of all AC types across the metrics that matter for purchasing decisions:

How to Reduce AC Electricity Use

The DOE data and independent studies point to a consistent set of high-impact strategies. Here they are ranked by typical electricity savings:

On the structural side: adding attic insulation is among the highest-ROI improvements for reducing AC load. A properly insulated attic (R-38 to R-60 depending on climate zone) can reduce cooling load by 10–15%. Sealing duct leaks can recover 20–30% of the cooled air currently lost before it reaches your living spaces. Learn more in our Complete Home Insulation Guide.

Frequently Asked Questions