This setup: $0.38/hr to run · 2,189 kWh/season
Monthly Cost
$93
/mo
during the cooling season · $0.38/hr
Seasonal Cost
$372
per year
Cost Per Hour
$0.38
2.25 kW draw
Monthly Energy
547
kWh/mo
Seasonal Energy
2,189
kWh/yr
973 runtime hours per cooling season
How we calculated this
= 2.25 kW
= $0.38/hr
547 kWh × $0.17/kWh = $93/mo
2.25 kW × 973 hrs = 2,189 kWh
2,189 kWh × $0.17/kWh = $372/yr
Estimates only. Real cost depends on actual runtime, duct losses, humidity, and rate tiers. SEER is a seasonal average, so hourly draw varies with outdoor temperature. Treat this as a planning figure.
Reference
Typical Monthly Cost by Size & SEER
Average monthly running cost during the cooling season, assuming 8 hours of compressor runtime a day at $0.17/kWh. Your numbers move with your runtime and local rate, so use the calculator above.
| System Size | SEER 14 | SEER 16 | SEER 20 |
|---|---|---|---|
| 2 ton | $71 | $62 | $50 |
| 3 ton | $106 | $93 | $74 |
| 4 ton | $142 | $124 | $99 |
| 5 ton | $177 | $155 | $124 |
Learn
Understanding AC Running Costs
What drives your AC's running cost
Three things set the bill: how much power the unit draws, how long it runs, and what you pay per kilowatt-hour. Power draw comes straight from the system's size and efficiency: a bigger or less efficient unit pulls more watts for every hour it runs. Runtime is set by your climate, insulation, and thermostat habits. The rate is whatever your utility charges. Change any one and the cost moves with it.
The formula
Start with power draw: kW = tons × 12,000 BTU/hr ÷ SEER ÷ 1,000. A 3-ton SEER 16 unit is 3 × 12,000 ÷ 16 ÷ 1,000 = 2.25 kW. Multiply by your rate for cost per hour (2.25 × $0.17 = $0.38), by daily runtime for the daily cost, and by the days in your cooling season for the seasonal total. SEER is a seasonal average rather than an instantaneous reading, so treat the result as a solid estimate, not a meter reading.
Why SEER and runtime matter most
SEER sits in the denominator, so efficiency scales the whole bill: a SEER 20 unit costs about 35% less per hour than a SEER 13 unit of the same size. Runtime is the other big lever. The same air conditioner can cost three to four times as much over a season in Phoenix as in Seattle, because it runs both more months of the year and more hours per day. Tonnage matters too, but an oversized unit doesn't save money; it short-cycles, runs less efficiently, and dehumidifies poorly.
Cutting the cost without replacing the unit
Before spending on new equipment, claw back runtime. A programmable or smart thermostat that eases the setpoint up a few degrees while you're out trims hours directly. Clean filters monthly and keep the outdoor coil clear so the compressor isn't fighting restricted airflow. Seal and insulate ducts that run through a hot attic, where losses can top 20%. Shade the condenser and block afternoon sun on west-facing glass. Each one shaves runtime, and runtime is what you pay for.
When an upgrade pays off
If your unit is low-SEER, runs long hours, and you pay a high rate, a high-efficiency replacement can pay for itself well within its lifespan. If you cool only a few weeks a year or pay a low rate, the energy savings rarely cover the upcharge before the unit wears out. Run your own numbers; the upgrade math hinges on the same runtime and rate figures you entered above.
FAQ
Common Questions About AC Operating Cost
How much does it cost to run an AC per hour?
A 3-ton, SEER 16 central AC draws about 2.25 kW. At a typical rate of $0.17/kWh that works out to roughly $0.38 per hour of runtime. A less efficient SEER 13 unit of the same size runs about $0.47/hr; a high-efficiency SEER 20 unit drops to about $0.31/hr. Multiply by how many hours a day the compressor actually runs, not how long the thermostat is set.
How do you calculate AC running cost?
Power draw in kilowatts is tons × 12,000 BTU/hr ÷ SEER ÷ 1,000. Multiply that by your electricity rate for the cost per hour, then by daily runtime and the number of days to get the monthly and seasonal totals. A 3-ton SEER 16 unit running 8 hours a day at $0.17/kWh comes out to roughly $93 a month during the cooling season. The calculator above does the whole chain live.
Does a higher SEER lower my running cost?
Yes. Running cost is inversely proportional to SEER, so a higher rating means a smaller bill for the same cooling. SEER 13 → 16 trims energy use about 19%; SEER 13 → 20 about 35%. Whether that upgrade is worth the upfront cost depends on your runtime and rate. The SEER Savings Calculator works out the annual savings and payback period.
Why is my AC bill so high?
The big drivers are an oversized or low-efficiency unit, long runtimes in a hot climate, and a high electricity rate. On top of that, dirty filters and coils, leaky ducts in an unconditioned attic, and a very low thermostat setpoint all push runtime up, and cost follows. Right-sizing matters: an oversized unit short-cycles and an undersized one never shuts off, and both waste energy. The AC Size Calculator checks whether yours is matched to the space.
How many hours a day does an AC run?
A correctly sized unit runs roughly 8–12 hours a day on a typical summer day, cycling on and off rather than running flat out. On a design-day heat wave it can approach 16 hours. The number that matters for cost is actual compressor runtime, not how long the system is switched on; the thermostat satisfies and the compressor rests between cycles.
Related Tools
SEER Savings Calculator
See annual savings and payback when you upgrade to a higher-SEER unit.
↳ SEER 13 → 18 · 3 tons · hot → ~$330/yr saved
AC Size Calculator
Check your unit is sized right. An oversized AC wastes money every hour.
↳ 1,500 sq ft · moderate → ~2.5 ton
BTU Calculator
Size a window, portable, or mini-split AC for a single room.
↳ 300 sq ft · hot & humid · sunny → ~12,500 BTU