Air conditioning costs between $20 and $245 per month, depending on your AC type, how many hours you run it, and your electricity rate. A window unit in a bedroom costs far less than central AC cooling a large home. But the single biggest variable most people overlook is the rate they pay per kilowatt-hour.
At the U.S. average rate of $0.17/kWh, a 2-ton central AC running 8 hours daily costs roughly $98 per month. That same AC costs $115 per month at Pennsylvania's higher rates — or $69 per month if you've shopped for a competitive supplier at 12¢/kWh. The rate multiplies across every hour of runtime.
AC cost by type
Different AC systems vary dramatically in power consumption. Here's what each type typically costs to run at $0.17/kWh:
| AC Type | Typical Size | Watts | Daily Cost (8 hr) | Monthly Cost |
|---|---|---|---|---|
| Window AC (small room) | 5,000 BTU | 500W | $0.68 | $20 |
| Window AC (large room) | 12,000 BTU | 1,200W | $1.63 | $49 |
| Portable AC | 10,000 BTU | 1,000W | $1.36 | $41 |
| Central AC (small home) | 2 tons | 2,400W | $3.26 | $98 |
| Central AC (large home) | 5 tons | 6,000W | $8.16 | $245 |
| Mini-split | varies | 700-1,500W | $0.95-$2.04 | $29-$61 |
The spread is significant. A household with a single window unit cooling one bedroom pays about $20/month. A household with central AC in a 3,000+ square foot home can easily exceed $200/month during peak summer.
What affects your AC's monthly cost
Six factors determine what you actually pay:
BTU capacity
Air conditioner size is measured in BTUs (British Thermal Units) or tons (1 ton = 12,000 BTU). Larger units use more electricity. A 5-ton system uses roughly 2.5 times the electricity of a 2-ton system when running.
Runtime hours
This is the most variable factor. An AC in Phoenix might run 12+ hours daily in July. An AC in Pittsburgh might run 4-6 hours. Double the runtime means double the cost.
Your electricity rate
This is where most people leave money on the table. At $0.17/kWh, 8 hours of central AC costs $3.26/day. At $0.12/kWh — achievable in deregulated states by shopping suppliers — that same usage costs $2.30/day. That's $29/month in savings from rate alone, with zero change in comfort.
Local climate
Hotter climates mean more runtime. Humid climates make AC work harder (removing moisture requires energy). A home in Houston runs AC more hours annually than a home in Philadelphia.
Home insulation
Poor insulation means conditioned air escapes and hot air enters. A well-insulated home might cycle AC 30-40% of the time. A poorly insulated home might run continuously. The insulation difference can double your AC costs in the same climate.
Thermostat setting
Each degree you lower your thermostat increases AC runtime by roughly 3%. Setting the thermostat at 72°F instead of 78°F can increase cooling costs by 18% or more.
Math example: Pennsylvania summer
Here's the calculation for a typical Pennsylvania household:
Setup:
- 2-ton central AC (2,400 watts)
- 8 hours daily runtime during a hot July
- 30 days
- Rate: $0.17/kWh (Pennsylvania average)
Calculation:
2,400W × 8 hours = 19,200 Wh = 19.2 kWh/day
19.2 kWh × 30 days = 576 kWh/month
576 kWh × $0.17 = $97.92/month
Now the same AC at a competitive supplier rate of $0.12/kWh:
576 kWh × $0.12 = $69.12/month
Savings from rate shopping: $28.80/month
That's $86/summer for a single rate change — with zero impact on comfort or usage.
State-by-state rate variation
Your electricity rate varies dramatically by state. The same AC running the same hours costs different amounts depending on where you live:
| State | Avg. Rate | Monthly AC Cost (2-ton, 8 hr/day) |
|---|---|---|
| Hawaii | $0.45/kWh | $259 |
| California | $0.32/kWh | $184 |
| Massachusetts | $0.29/kWh | $167 |
| Pennsylvania | $0.17/kWh | $98 |
| Texas | $0.15/kWh | $86 |
| Louisiana | $0.12/kWh | $69 |
Residents of high-rate states feel AC costs most acutely. But in deregulated states — Pennsylvania, Texas, Ohio, and others — you have the option to shop for a lower supply rate.
The biggest lever: rate shopping
Most advice about reducing AC costs focuses on usage: raise the thermostat, use fans, seal air leaks. These tips help, but they typically save 10-20% at best.
Rate shopping in deregulated states can save 20-30% with no change in usage.
Consider: if your AC is running 8 hours a day in summer, you can't realistically cut that to 4 hours without being uncomfortable. But you might pay $0.10/kWh instead of $0.14/kWh by switching suppliers.
In Pennsylvania, competitive suppliers currently offer rates as low as 9-10¢/kWh compared to utility default rates of 11-14¢/kWh. For a household using 576 kWh monthly on AC alone, that rate difference saves $17-23/month.
See what suppliers offer in your area at Pennsylvania electricity plans.
How to reduce your AC's electricity cost
Beyond rate shopping, these steps genuinely reduce AC costs:
Raise the thermostat
The Department of Energy recommends 78°F when home. Each degree above 72°F saves about 3% on cooling costs. Going from 72°F to 78°F can reduce AC costs by 18%.
Use ceiling fans
Fans allow you to raise the thermostat 4°F while maintaining comfort. A ceiling fan costs about 1¢/hour to run vs. 30-60¢/hour for central AC. The savings math is favorable.
Service your AC
A dirty filter restricts airflow and increases energy consumption by 5-15%. Annual professional service catches refrigerant issues and keeps the system efficient.
Block sun on windows
Direct sunlight through windows can add 10-20% to your cooling load. Blinds, curtains, and exterior shading reduce how hard your AC works.
Seal air leaks
Conditioned air escaping through gaps around windows, doors, and outlets means your AC runs longer. Basic weatherstripping and caulk are cheap and effective.
Consider a programmable thermostat
Letting the house warm up while you're away and cooling it before you return can reduce daily AC runtime by 1-2 hours.
PA-specific: what you can control
Pennsylvania's deregulated electricity market means you have options most Americans don't.
Your local utility — PECO, PPL, Duquesne Light, or one of the FirstEnergy companies — delivers electricity to your home. This cost is fixed and regulated. But the supply side — the electricity generation itself — is open to competition.
Pennsylvania's "Price to Compare" is the default rate you pay for supply if you don't choose a competitive supplier. As of June 2026, these rates range from 11-14¢/kWh depending on your utility. Competitive suppliers offer rates starting around 9-10¢/kWh.
For a household running AC heavily in summer, the difference between 14¢ and 10¢ is substantial: $23/month on 576 kWh of AC usage alone.
Switching takes 5 minutes. Your utility still handles delivery, billing, and outages. The only thing that changes is who supplies your electricity — and what you pay per kWh.
For step-by-step instructions, see our guide to switching suppliers in Pennsylvania.
FAQ
How much does it cost to run central AC for 24 hours?
At $0.17/kWh with a 2-ton (2,400W) system, running AC continuously for 24 hours costs about $9.79. Larger systems cost proportionally more: a 5-ton system running 24 hours costs roughly $24.48. These are unusual scenarios — most systems cycle on and off rather than running continuously — but useful for understanding the upper bound.
Is it cheaper to leave AC on all day or turn it off?
It's generally cheaper to turn AC off (or raise the thermostat significantly) when you're away, then cool the house when you return. Modern AC systems cool a warm house more efficiently than older wisdom suggested. However, if you're only away for 2-3 hours, the savings are minimal. Programming your thermostat to raise temperatures during work hours and cool before you return is the most efficient approach.
How can I tell what my AC is costing me each month?
Compare your summer electric bills to your spring or fall bills. The difference is mostly AC. For a more precise measurement, check your AC unit's wattage (on the label or in the manual), estimate your daily runtime, and multiply by your electricity rate. A smart meter or energy monitor can track usage in real-time.
Are smart thermostats actually worth it?
Smart thermostats typically reduce cooling costs by 8-15% compared to manual thermostats left at a constant setting. At 576 kWh/month of AC usage ($98/month), that's $8-15/month in savings. A smart thermostat costs $100-250. If it saves $10/month over a 5-month cooling season, it pays for itself in 2-5 years. The math is reasonable but not dramatic.
Does AC type or rate matter more for monthly cost?
Both matter, but they affect different parts of your cost. AC type determines your baseline consumption — you can't change a central AC system's power draw. Your electricity rate multiplies that consumption into dollars. In practice, you're unlikely to replace your AC system to save on monthly costs (the economics rarely work), but you can change your rate in minutes if you're in a deregulated state.