How much electricity does an air conditioner use per hour?

A typical 2-ton (24,000 BTU) central AC with 18 SEER uses about 1.33 kWh per hour of operation. A window unit at 8,000 BTU/12 SEER uses about 0.67 kWh per hour. Divide BTU/hr by SEER to get watts, then divide by 1,000 for kilowatts.

How many solar panels does it take to power an AC?

A 1.5 kW AC running 8 hours per day uses 12 kWh daily. With 400W panels and 4.5 peak sun hours, each panel produces about 1.5 kWh/day, so you'd need 8 panels to cover daytime AC use. Add battery storage for nighttime operation.

AC Cost Calculator

How much does your air conditioner cost to run? Enter BTU and SEER — get hourly, daily, and seasonal electricity costs.

Air conditioner details

AC cooling capacity?

BTU/hr

SEER rating?

Hours per day?

hrs/day

Electricity rate?

$/kWh

Cooling season length?

months/yr

Electricity draw: 1,333W (1.33 kW)

48.00/month • 320 kWh/month

Cost per hour$0.20/hr

Cost per day$1.60/day

Seasonal cost$192.00/yr

Solar to offset~7 panels

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How to Use This Calculator

Find your AC's BTU rating

Your air conditioner's cooling capacity is rated in BTU per hour (BTU/hr). You'll find this on the yellow EnergyGuide label, the unit's nameplate, or in the owner's manual. Window units typically range from 5,000 to 25,000 BTU/hr. Central AC systems are often described in "tons" — multiply tons × 12,000 to get BTU/hr (a 2-ton AC = 24,000 BTU/hr).

Enter the SEER rating

SEER (Seasonal Energy Efficiency Ratio) is your AC's efficiency rating — higher SEER = less electricity consumed. Minimum SEER for new central ACs since 2023 is 14-15 depending on region. Older units from 2005-2015 typically run 10-13 SEER. High-efficiency units reach 18-25 SEER. The EnergyGuide label shows your unit's SEER.

Set usage hours and cooling season

Enter the average hours per day your AC runs during cooling season (includes compressor on-time, not just thermostat calls). Then set your cooling season length in months — this varies dramatically by climate: 2-3 months in northern states, 5-8 months in Florida and Gulf Coast.

The Formula

Power draw (W) = BTU/hr ÷ SEER Power draw (kW) = Watts ÷ 1,000 kWh per hour = kW × 1 hour kWh per day = kW × hours per day kWh per month = kWh/day × 30 days Seasonal kWh = kWh/day × 30 × cooling months Cost = kWh × electricity rate ($/kWh)

The SEER formula works because SEER is defined as total BTU of cooling delivered per watt-hour of electricity over a cooling season. At any given operating point: watts = BTU/hr ÷ SEER. This is a simplification — actual efficiency varies with outdoor temperature — but it's the standard engineering approximation used by the Department of Energy.

The solar offset estimate uses 400W panels with 4.5 peak sun hours and 86% system efficiency to determine how many panels would cover your seasonal AC energy consumption.

Example

2-ton central AC — Atlanta, GA

An Atlanta homeowner runs a 2-ton (24,000 BTU/hr) central AC with an 18 SEER rating for 8 hours per day over a 5-month cooling season. Atlanta electricity costs about $0.13/kWh.

Cooling capacity24,000 BTU/hr (2 tons)

SEER rating18

Hours per day8 hrs

Electricity rate$0.13/kWh

Cooling season5 months

Result

Power draw1,333W (1.33 kW)

Daily energy use10.7 kWh/day

Monthly cost$41.60/month

Seasonal cost$208/year

Solar panels to offset~5 panels

Five 400W solar panels — just $1,000-1,500 worth of panels — would offset the annual cost of running this efficient AC. Upgrading from a 10 SEER to an 18 SEER unit reduces electricity consumption by 44%, saving over $165 per year in this example.

FAQ

How many solar panels does it take to run an air conditioner? ▼

A 1.5 kW AC unit running 8 hours per day uses 12 kWh/day. With 4.5 peak sun hours and 400W panels (at 86% efficiency), each panel produces about 1.5 kWh/day. You'd need 8 panels to run this AC from solar during daylight hours. To also run it at night from battery storage, you'd need additional battery capacity. Our Solar Panel Calculator can size a system for your whole home including AC.

What is the difference between SEER and EER? ▼

EER (Energy Efficiency Ratio) is a single-point efficiency rating measured at 95°F outdoor temperature, 80°F indoor dry bulb, and 50% humidity. SEER (Seasonal EER) is a more realistic measure that accounts for varying outdoor temperatures throughout the cooling season. SEER is generally 10-20% higher than EER for the same unit. SEER is the standard rating used in the US for comparing units and is the number on the EnergyGuide label.

Is a higher SEER AC worth the extra cost? ▼

Going from 14 SEER to 18 SEER reduces electricity consumption by 22% — significant if you use AC heavily. Going from 18 SEER to 22 SEER saves another 18%. The premium for a 22 SEER vs 16 SEER unit is typically $500-1,500. If you spend $400/year on AC, a 22 SEER unit might save $100/year over a 16 SEER, paying back the premium in 5-15 years. In hot climates (Florida, Texas, Arizona), higher SEER is almost always worth it. In cooler climates with short cooling seasons, the payback extends significantly.

Should I replace my AC with a heat pump? ▼

If you heat with gas or oil, a heat pump can provide both heating and cooling at significantly lower total energy cost. Modern heat pumps achieve COP (coefficient of performance) of 2-4x for heating — meaning they deliver 2-4 units of heat per unit of electricity, compared to a gas furnace's less-than-1x ratio. For cooling, heat pumps and dedicated ACs have similar SEER ratings. Use our Heat Pump Calculator to compare total annual costs.