Air Conditioner Running Cost Calculator
Air conditioning can dominate summer bills. Enter your AC’s cooling capacity, efficiency, runtime, and electricity rate to estimate what it costs to run.
Quick answerA 12,000 BTU/h air conditioner rated EER 10 draws about 1,200 W at full load. At $0.17/kWh, that is about $0.20 per hour, $1.63 for 8 hours, $48.96 per 30 days, or $195.84 across 120 cooling days. Thermostat cycling and inverter operation can lower the average, so use the duty-cycle field or a measured kWh reading for a closer estimate.
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Cooling capacity ÷ EER; compare with the product label or a compatible meter.
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How it works
Full-load power (watts) = BTU/h ÷ EER. Average power = full-load power × duty cycle ÷ 100. Cost per switched-on hour = average power ÷ 1,000 × electricity rate. Daily cost = hourly cost × hours switched on; the 30-day and seasonal figures multiply that daily estimate by 30 and by your cooling days. A higher EER means less full-load power for the same cooling capacity.
AC running cost by common cooling capacity
These full-load examples use EER 12 and an electricity rate of $0.17/kWh. They are formula examples, not measured values for a specific air conditioner.
| Cooling capacity | Calculated full-load power | Cost per full-load hour |
|---|---|---|
| 5,000 BTU/h | 417 W | $0.07 |
| 8,000 BTU/h | 667 W | $0.11 |
| 10,000 BTU/h | 833 W | $0.14 |
| 12,000 BTU/h | 1,000 W | $0.17 |
| 18,000 BTU/h | 1,500 W | $0.26 |
| 24,000 BTU/h | 2,000 W | $0.34 |
Actual average demand can be lower when a thermostat cycles the compressor or an inverter unit modulates its output. Enter your own rate and duty cycle above.
Worked example: a 12,000 BTU air conditioner
With a 12,000 BTU/h cooling capacity and EER 10, calculated full-load power is 12,000 ÷ 10 = 1,200 W. At $0.17/kWh, one full-load hour costs 1.2 kW × $0.17 = $0.204. Eight hours per day costs about $1.63; 30 equal days cost $48.96; and 120 cooling days cost $195.84.
If the compressor averages a 60% duty cycle during those eight switched-on hours, the calculator reduces average power to 720 W and the seasonal estimate to about $117.50. That percentage is an assumption unless you measure the unit over representative hot and mild days.
EER, CEER, SEER, and SEER2 are not interchangeable inputs
EER compares the average cooling rate with the average electrical input at a defined rating condition. CEER is the metric commonly shown for room air conditioners and also accounts for certain standby or off-mode energy. SEER and SEER2 describe seasonal performance under standardized test procedures for central systems.
This calculator uses the simple BTU/h ÷ efficiency relationship, so an EER or CEER figure is the closest fit. Do not paste a SEER or SEER2 number into the EER field and treat the result as exact. For a central or variable-speed system, its published annual kWh, installer performance data, utility interval data, or a properly installed energy monitor can provide a better cost basis.
Why the real bill may differ from the estimate
Outdoor temperature, humidity, thermostat setting, insulation, air leakage, shade, filter condition, duct losses, equipment sizing, and installation quality all affect runtime and power. A nameplate can show rated or maximum input rather than the average across a day.
For a compatible 120 V plug-in room air conditioner, a plug-in energy meter can measure accumulated kWh without opening an electrical panel. Do not use a plug-in meter on a hard-wired, 240 V, or higher-current system. Central and mini-split equipment should be assessed using its own documentation, utility data, or qualified electrical/HVAC help.
Sources used for assumptions: ENERGY STAR — room air conditioner efficiency criteria and CEER tables; U.S. Department of Energy — definitions of EER and seasonal efficiency metrics; U.S. Department of Energy — central air conditioner selection, installation, and operating guidance.
Frequently asked questions
How much does an air conditioner cost to run per hour?
Divide BTU/h by EER to estimate watts, divide by 1,000, then multiply by your electricity rate and duty-cycle fraction. A 12,000 BTU/h unit at EER 10 costs about $0.20 per full-load hour at $0.17/kWh.
How much does a 12,000 BTU air conditioner cost per month?
At EER 10, $0.17/kWh, 8 hours per day, and 100% duty cycle, the estimate is $48.96 per 30 days. A 60% average duty cycle would reduce the same arithmetic estimate to about $29.38.
What duty cycle should I enter?
Use 100% for a conservative full-load estimate. If you know the compressor runs about half the time while the unit is switched on, use 50%. Inverter systems vary output rather than simply switching fully on and off, so measured kWh is more reliable.
Can I use SEER or SEER2 in the EER field?
No, not for an exact result. EER/CEER and SEER/SEER2 come from different rating approaches. Use EER or CEER for this simple full-load calculation, or use published annual kWh or measured energy for a central system.
What is a good EER or CEER?
Higher is more efficient, but the applicable threshold depends on capacity and product type. ENERGY STAR room-air-conditioner criteria use capacity-specific CEER values, so compare the exact model with the current certification criteria rather than relying on one universal cutoff.
How can I lower AC running costs?
Avoid cooling empty rooms, use sensible thermostat schedules, shade sun-facing windows, seal leaks, keep filters clean, and maintain the equipment. Correct sizing and installation also matter; oversized or poorly installed central systems can lose efficiency.
How many BTU are in one ton of cooling?
12,000 BTU/h equals 1 ton of cooling capacity, so 24,000 BTU/h is 2 tons. Tons describe cooling capacity, not the unit’s electrical power draw.
Can I measure my AC with a plug-in energy meter?
Only if it is a compatible plug-in appliance within the meter’s voltage and current ratings. Do not use one on hard-wired, 240 V, or central equipment. Use manufacturer guidance and qualified help when electrical access is required.
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