Cooling · Montana
How Much Does It Cost to Run a Window Air Conditioner in Montana?
The short answer
A typical 900W window air conditioner costs about $0.13 per hour to run in Montana, or $32.83 a month at 8 hours a day.
Montana’s average residential rate was 15.0¢ per kWh in July 2026 (EIA), 18% below the US average.
Source: U.S. EIA, July 2026 data · Updated
Window Air Conditioner cost by daily use in Montana
| Daily use | kWh/month | Per day | Per month | Per year |
|---|---|---|---|---|
| 1 hour/day | 27.4 | $0.13 | $4.10 | $49.24 |
| 2 hours/day | 54.8 | $0.27 | $8.21 | $98.48 |
| 4 hours/day | 109.5 | $0.54 | $16.42 | $197 |
| 8 hours/day | 219.0 | $1.08 | $32.83 | $394 |
| 12 hours/day | 328.5 | $1.62 | $49.25 | $591 |
| 24 hours/day | 657.1 | $3.24 | $98.50 | $1,182 |
Montana vs other states
At typical use, a window air conditioner costs $394 a year in Montana — $868 less than in Hawaii and $59.66 more than in Louisiana.
Montana has the 14th-cheapest residential electricity of the 50 states and DC. electricity prices in Montana · all states ranked
Electricity price trend in Montana
15.0¢/kWh in July 2026 — ▲ +5.0% from a year earlier.
How to lower the cost of running a window air conditioner
Window air conditioners cool a single room and are far cheaper to run than central AC when you only need one or two rooms cool. Wattage scales with capacity: small 5,000 BTU units draw around 450–500W, a 10,000 BTU unit around 900W, and large 15,000+ BTU units 1,300–1,500W. ENERGY STAR models with inverter compressors can use 20–35% less. The compressor cycles with the thermostat, so enter the hours it actually runs.
- Pick the right size — an oversized unit cycles constantly and dehumidifies poorly.
- Seal the gaps around the unit with foam strips to keep hot air out.
- Clean the washable filter every two weeks in peak season.
- Summers in Montana are relatively mild, so cooling costs are concentrated in a few hot weeks each year.
Questions
Frequently asked questions
How much does it cost to run a window air conditioner for 24 hours in Montana?
Running a 900W window air conditioner for 24 hours uses about 21.6 kWh, which costs about $3.24 at Montana’s average rate of 15.0¢/kWh.
How many kWh does a window air conditioner use per month?
At 8 hours a day, a typical window air conditioner uses about 219 kWh a month. In Montana that costs $32.83.
Is it expensive to run a window air conditioner in Montana?
Montana has the 14th-cheapest residential electricity of the 50 states and DC at 15.0¢/kWh — cheaper than most. Running a window air conditioner here costs about $394 a year at typical use, compared with $481 at the national average rate.
What is the electricity rate in Montana right now?
The average residential electricity rate in Montana was 15.0¢ per kWh in July 2026, according to the latest EIA data — up 5.0% from a year earlier.
Is a window AC cheaper to run than central air?
For cooling one or two rooms, yes. A 900W window unit uses about a quarter of the power of a typical 3,500W central system.
Window Air Conditioner costs in nearby states
Other appliances in Montana
Cheapest and priciest states
Comparisons
Sources & method
- Electricity rates: U.S. Energy Information Administration, Electric Power Monthly — average residential retail price, July 2026 (latest available). Retrieved .
- CO₂: EIA State Electricity Profiles, 2024 emissions rate of in-state power generation.
- Default usage for window air conditioner: 8 hours a day. Typical power 900W.
- Formulas, duty cycles and limitations: methodology. Data download: open data (CC BY 4.0).