Air Conditioner Running Cost Calculator
Work out what your AC costs to run per hour, day, month and cooling season. Enter the BTU size and SEER2, SEER or EER rating (or just the watts), your hours of use and electricity rate, then see how much a more efficient unit or a higher thermostat setting would save.
Last updated:
12,000 BTU/h = 1 ton. Optional in watts mode (used for efficiency and the upgrade comparison).
On the yellow EnergyGuide label or spec sheet.
From the nameplate, manual or a plug-in watt meter.
Share of those hours the compressor actually runs. 100% = always on; mild days are often 50–70%.
From your bill. US residential average was about $0.16–0.17/kWh in 2024 (EIA).
Set 0 to skip the season total.
Same rating type as above (EER when you entered watts). Leave empty to skip.
Leave empty to skip.
Rule of thumb used by many utilities: about 3% of cooling energy per °F (capped at 50%).
How to use the Air Conditioner Running Cost Calculator
- Choose how you know the unit: its BTU capacity and efficiency rating, or its power draw in watts.
- Enter the BTU and rating from the EnergyGuide label (SEER2 on new central and mini-split units, CEER on window units).
- Add your usage: hours per day, how much of that time the compressor runs, and days per month.
- Type your electricity rate per kWh from your utility bill.
- Press Calculate cost to see the cost per hour, day, month and season, then compare a higher-rated unit or a warmer thermostat setting.
How AC running cost is calculated
An efficiency rating tells you how many BTU of heat the unit removes for each watt-hour of electricity. Dividing the capacity by the rating gives the power draw:
- Watts = BTU/h ÷ rating (SEER2, SEER, EER or CEER)
- kWh per hour = watts ÷ 1,000 × compressor run time
- Cost per hour = kWh per hour × electricity rate
- Cost per month = cost per hour × hours per day × days
Example: a 12,000 BTU/h mini-split rated 20 SEER2 draws 12,000 ÷ 20 = 600 W. Running 10 hours a day with the compressor on 70% of the time, it uses 0.6 × 0.7 × 10 = 4.2 kWh a day. At $0.17/kWh that is about $0.71 a day, or $21.42 for a 30-day month.
SEER and SEER2 are seasonal averages, so they suit monthly estimates. EER is measured at a steady 95°F outdoors and gives a higher, worst-case hot-afternoon figure. If you can measure the unit with a plug-in watt meter (window and portable units), choose the watts option for the most accurate result.
Typical power draw by AC type
| Unit | Capacity | Typical rating | Approx. watts | Cost per hour at $0.17/kWh |
|---|---|---|---|---|
| Small window unit | 6,000 BTU/h | CEER 11 | 545 W | $0.09 |
| Medium window unit | 10,000 BTU/h | CEER 12 | 833 W | $0.14 |
| Portable AC | 8,000 BTU/h (SACC) | CEER 7–9 | 900–1,150 W | $0.15–0.19 |
| Ductless mini-split | 12,000 BTU/h | SEER2 20 | 600 W | $0.10 |
| Central air, 2 tons | 24,000 BTU/h | SEER2 14.3 | 1,678 W | $0.29 |
| Central air, 3 tons | 36,000 BTU/h | SEER2 14.3 | 2,517 W | $0.43 |
| Central air, 4 tons | 48,000 BTU/h | SEER2 14.3 | 3,357 W | $0.57 |
Figures are while the compressor runs; the blower fan of a central system adds a little more. Since January 2023 the US minimum for new central air conditioners is 13.4 SEER2 in northern states and 14.3 SEER2 (13.8 for systems of 45,000 BTU/h and larger) in the Southeast and Southwest.
Tips to lower your cooling bill
- Raise the setpoint. 78°F while home and higher while away is a common energy-saving target; a ceiling fan lets most people feel comfortable about 4°F warmer.
- Keep the coils and filter clean. A clogged filter or dirty condenser coil makes the compressor run longer for the same cooling.
- Size it right. An oversized unit short-cycles and dehumidifies poorly; an undersized one runs nonstop on hot days. Check with a BTU sizing calculator.
- Block the sun. Closing blinds on south and west windows in the afternoon cuts the heat the AC has to remove.
- Check your rate plan. On time-of-use plans, pre-cooling before the peak window and coasting through it can cut cost even if kWh stay the same.
Frequently asked questions
How much does it cost to run an air conditioner per hour?
Divide the BTU/h capacity by the efficiency rating to get watts, convert to kilowatts and multiply by your rate. A 12,000 BTU unit rated 14.3 SEER2 draws about 839 W, so at $0.17/kWh it costs about 14 cents per hour while the compressor runs. A 3-ton (36,000 BTU) central unit at SEER 14 draws about 2,570 W, roughly 44 cents an hour.
How do I calculate AC watts from BTU and SEER?
Watts = BTU per hour ÷ SEER. SEER is BTU of cooling per watt-hour of electricity over a season, so a 24,000 BTU/h system with SEER 16 uses about 24,000 ÷ 16 = 1,500 W on average. Use EER instead of SEER for a hot-day (95°F) peak estimate.
What is the difference between SEER, SEER2, EER and CEER?
SEER is a seasonal average efficiency. SEER2, used on US labels since January 2023, is tested with higher fan static pressure, so the same unit scores about 4–5% lower than its old SEER. EER (and EER2) measures efficiency at a steady 95°F outdoor temperature, so it is lower than SEER. CEER is the combined rating used for room (window) air conditioners and includes standby power.
How much can a higher SEER air conditioner save?
Energy use scales with 1 ÷ rating. Going from SEER 13 to SEER 18 cuts cooling electricity by 1 − 13/18, about 28%. If cooling costs you $150 a month in summer, that is roughly $42 a month. Whether the upgrade pays back depends on your climate, hours of use and the price difference.
Does raising the thermostat really save money?
Yes. A smaller gap between indoor and outdoor temperature means less heat to remove. Many utilities quote about 3% savings for each degree Fahrenheit you raise the setpoint, and the US Department of Energy says setting the thermostat higher while you are away can save up to 10% a year on cooling and heating. Treat these as estimates; actual savings depend on your home and climate.
Why is my real bill different from the estimate?
Air conditioners cycle on and off, so the compressor rarely runs every hour you are using it; use the run-time setting to account for that. Ratings are measured in lab conditions, and dirty filters, low refrigerant, leaky ducts or an undersized unit all raise real consumption. Rates with tiers, time-of-use pricing and fixed fees also change the true cost per kWh.
How many kWh does an air conditioner use per month?
Multiply kilowatts by hours of use and days. A 1,000 W window unit running 8 hours a day for 30 days uses 1 × 8 × 30 = 240 kWh a month. A 3-ton central system drawing about 3,000 W for 10 hours a day uses about 900 kWh a month.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.