There are 8 main types of air conditioners available in 2026: window units, portable ACs, ductless mini splits, central air systems, through-the-wall units, PTACs, evaporative coolers, and hybrid/dual-fuel systems. The right type for you depends on your cooling area, budget, installation constraints, and whether you rent or own.
This guide breaks down every AC type with hard specs, real costs, and honest pros and cons so you can make the right decision for your situation.
Quick Comparison: All AC Types at a Glance
| AC Type | Cooling Capacity | Upfront Cost | Annual Running Cost | Efficiency (Rating) | Noise Level | Installation |
|---|---|---|---|---|---|---|
| Window AC | 5,000–25,000 BTU | $150–$700 | $30–$180 | CEER 10–15+ | 38–56 dB | DIY (30 min) |
| Portable AC | 6,000–14,000 BTU | $250–$700 | $50–$220 | CEER 8–11 | 48–58 dB | DIY (10 min) |
| Ductless Mini Split | 9,000–48,000 BTU | $1,500–$5,000 | $40–$150 | SEER2 15–42 | 19–45 dB | Professional |
| Central Air (Split) | 18,000–60,000 BTU | $3,500–$12,000 | $200–$600 | SEER2 14–26 | 55–75 dB (outdoor) | Professional |
| Through-the-Wall | 8,000–14,000 BTU | $400–$800 | $40–$140 | CEER 10–13 | 42–54 dB | Professional |
| PTAC | 7,000–15,000 BTU | $600–$1,200 | $60–$180 | EER 9–13 | 45–55 dB | Professional |
| Evaporative Cooler | N/A (CFM rated) | $100–$3,000 | $15–$60 | N/A | 40–65 dB | DIY or Pro |
| Hybrid/Dual-Fuel | 18,000–60,000 BTU | $5,000–$15,000 | $150–$500 | SEER2 16–22 | 55–75 dB (outdoor) | Professional |
1. Window Air Conditioners
Window ACs are self-contained cooling units that install in a standard double-hung window. They remain the most popular single-room cooling solution in the U.S., with over 10 million units sold annually.
How They Work
A single unit contains both the evaporator (indoor cooling) and condenser (outdoor heat rejection) sections. The indoor fan circulates room air over the cold evaporator coil, while the outdoor fan exhausts absorbed heat through the condenser coil. A compressor — either fixed-speed or inverter — pumps refrigerant between the two coil sets.
Specs and Performance
| Specification | Range |
|---|---|
| Cooling Capacity | 5,000–25,000 BTU |
| Efficiency (CEER) | 10.0–15.5 |
| Noise Level | 38–56 dB |
| Weight | 36–130+ lbs |
| Power | 120V or 230V (above 15,000 BTU) |
| Typical Lifespan | 8–12 years |
| Coverage Area | 150–1,500 sq ft |
Subcategories
Window ACs now come in several form factors: standard, U-shaped/saddle, low-profile/ClearView, and casement/vertical. U-shaped designs like the Midea U wrap around the window sash, leaving it partially open. Low-profile designs like the GE Profile ClearView block 80% less window space.
Pros
- Lowest upfront cost of any AC type ($150–$700)
- DIY installation in 20–45 minutes
- Widest range of BTU options
- Self-contained — no professional installation needed
- Easy to remove seasonally
Cons
- Blocks all or part of the window
- Can be heavy (larger units 80+ lbs)
- Noisier than mini splits
- Single-room cooling only
- HOA restrictions in some communities
Best For
Renters, budget-conscious homeowners, single-room cooling, and seasonal use in climates with 3–5 month cooling seasons.
Real-World Example: Sarah rents a 1-bedroom apartment in Boston. She bought a Midea 8,000 BTU U-Shaped unit for $330. It cools her 250 sq ft bedroom at 42 dB — quiet enough for sleeping. Her summer electricity increase averages $35/month for 4 months ($140 total). Total first-year cost: $470.
2. Portable Air Conditioners
Portable ACs sit on the floor and exhaust heat through a hose connected to a window adapter kit. They're the most convenient option when window ACs aren't possible, but they're significantly less efficient.
How They Work
Single-hose models pull room air across the evaporator, then exhaust warm air and moisture through the hose. This creates negative pressure in the room, pulling in warm outside air through gaps around doors and windows. Dual-hose models use a second hose to draw outdoor air over the condenser, avoiding the negative pressure problem.
Specs and Performance
| Specification | Range |
|---|---|
| Cooling Capacity | 6,000–14,000 BTU (DOE-adjusted) |
| Efficiency (CEER) | 8.0–11.0 |
| Noise Level | 48–58 dB |
| Weight | 50–80 lbs |
| Power | 120V (all models) |
| Typical Lifespan | 5–8 years |
| Coverage Area | 150–500 sq ft |
BTU ratings on portable ACs are confusing. Before 2017, manufacturers used "ASHRAE" BTU ratings that overstated real-world capacity. The DOE now requires "SACC" (Seasonally Adjusted Cooling Capacity) ratings that reflect actual performance. A portable AC marketed as "14,000 BTU (ASHRAE)" may only deliver 8,000–10,000 BTU (SACC/DOE). Always use the DOE/SACC number for comparison.
Pros
- No permanent installation — move between rooms
- Works with casement, sliding, and other non-standard windows
- No exterior visibility (good for HOA compliance)
- Setup takes 10 minutes
Cons
- 20–30% less efficient than window ACs at the same BTU
- Noisier (compressor is fully inside the room)
- Takes up 2–4 sq ft of floor space
- Exhaust hose limits placement (must reach a window)
- Water collection tank requires periodic emptying (some models)
- Single-hose models create negative pressure
Best For
Situations where window ACs are impossible — server rooms, windowless rooms with access to an adjacent window, casement windows (though casement window ACs now exist), or when HOA rules prohibit visible exterior units.
Real-World Example: Mike lives in a San Francisco condo with HOA rules banning window units. His 300 sq ft home office has a sliding window. He bought a dual-hose Whynter 12,000 BTU (SACC) portable for $480. It keeps the room at 74°F during summer, but runs louder (52 dB) than a comparable window unit and costs about $15/month more in electricity.
3. Ductless Mini Split Air Conditioners
Mini splits are two-part systems: a slim indoor unit (wall-mounted, ceiling cassette, or floor console) connected by refrigerant lines to an outdoor condenser/compressor. They're the most efficient single-zone cooling option available.
How They Work
The outdoor unit houses the compressor and condenser coil. Refrigerant flows through insulated copper lines (typically 15–50 ft) to the indoor unit, which contains the evaporator and fan. Most modern mini splits use inverter compressors that continuously adjust speed, maintaining precise temperature control within ±0.5°F.
Specs and Performance
| Specification | Range |
|---|---|
| Cooling Capacity | 9,000–48,000 BTU |
| Efficiency (SEER2) | 15–42 |
| Noise Level | 19–45 dB (indoor), 48–60 dB (outdoor) |
| Power | 120V or 230V |
| Typical Lifespan | 15–20 years |
| Coverage Area | 200–1,500+ sq ft |
Pros
- Best efficiency of any AC type (SEER2 up to 42)
- Whisper-quiet indoor operation (19–25 dB on low)
- Heating and cooling in one system (heat pump)
- No window blockage or ductwork needed
- Multi-zone capability (1 outdoor unit + up to 5 indoor units)
- Individual room temperature control
Cons
- High upfront cost ($1,500–$5,000 per zone installed)
- Requires professional installation
- Indoor unit visible on wall
- Refrigerant lines must penetrate exterior wall
- Annual professional maintenance recommended ($100–$200)
Best For
Homeowners looking for permanent, efficient cooling/heating. Homes without ductwork. Room additions, garages, or attics. Multi-zone applications where you want individual room control.
Real-World Example: The Johnsons converted their garage into a home office in Portland, OR. A Mitsubishi 12,000 BTU mini split installed for $3,200 provides both cooling (summer) and heating (winter). At SEER2 33, their combined annual cooling+heating cost is about $180 — less than a window AC and space heater combined. Noise at the desk: 22 dB (inaudible).
4. Central Air Conditioning (Split Systems)
Central AC uses an outdoor condenser/compressor unit connected to an indoor evaporator coil (usually in the furnace or air handler), distributing cooled air through ductwork to every room.
How They Work
The outdoor unit compresses and condenses refrigerant, sending it to the indoor evaporator coil where it absorbs heat from air flowing through the duct system. A blower fan in the air handler pushes this cooled air through supply ducts to each room, while return ducts bring warm air back to the evaporator.
Specs and Performance
| Specification | Range |
|---|---|
| Cooling Capacity | 18,000–60,000 BTU (1.5–5 tons) |
| Efficiency (SEER2) | 14.3–26+ |
| Noise Level | 55–75 dB (outdoor unit) |
| Power | 230V / 208V |
| Typical Lifespan | 15–20 years |
| Coverage Area | Whole house |
Cost Breakdown
| Component | Cost Range |
|---|---|
| Outdoor unit (condenser) | $1,500–$5,000 |
| Indoor coil + installation | $800–$2,500 |
| Total with existing ducts | $3,500–$7,500 |
| Total with new ductwork | $7,000–$15,000 |
Pros
- Cools the entire home evenly
- Out of sight (hidden ductwork, outdoor unit in yard)
- Most efficient for whole-home cooling
- Increases home value
- Pairs with furnace for year-round HVAC
Cons
- Highest upfront cost ($3,500–$15,000)
- Requires professional installation
- Ductwork needed (expensive to add: $3,000–$7,000)
- Duct losses reduce efficiency 20–30% if poorly sealed
- Cools entire home even if you only use 1–2 rooms
- Annual maintenance required
Best For
Homeowners with existing ductwork who want whole-home cooling. New construction. Homes where consistent temperature throughout is important.
Real-World Example: The Garcia family in Dallas, TX upgraded their 20-year-old central AC (SEER 10) to a new Carrier Infinity (SEER2 22) for $6,800 installed. Their summer electricity bill dropped from $380/month to $220/month — saving $640 per cooling season. The unit will pay for itself in energy savings within 6 years.
5. Through-the-Wall Air Conditioners
Through-the-wall (TTW) units are similar to window ACs but install in a permanent wall sleeve cut into an exterior wall. They don't occupy a window.
How They Work
Functionally identical to window ACs — same vapor-compression cycle, same component layout. The difference is the mounting: a metal sleeve (chassis) is permanently installed in the wall, and the AC unit slides into it. This allows easy removal for maintenance or replacement without disturbing the wall opening.
Specs and Performance
| Specification | Range |
|---|---|
| Cooling Capacity | 8,000–14,000 BTU |
| Efficiency (CEER) | 10.0–13.0 |
| Noise Level | 42–54 dB |
| Weight | 55–100 lbs |
| Power | 120V or 230V |
| Typical Lifespan | 10–15 years |
| Wall Sleeve Cost | $50–$120 (separate purchase) |
Pros
- Doesn't block any window
- Permanent, clean installation
- Easy unit replacement (slide out old, slide in new)
- Lower noise than window ACs (better insulation)
- More stable than window-mounted units
Cons
- Requires cutting a hole in an exterior wall
- Professional installation recommended
- Limited BTU range compared to window ACs
- Higher upfront cost (unit + sleeve + installation)
- Not suitable for renters
Best For
Rooms without suitable windows, permanent installations in owned homes, buildings where window units are prohibited, hotels, and commercial spaces.
6. PTAC (Packaged Terminal Air Conditioners)
PTACs are the commercial-grade through-the-wall units you see in hotels, hospitals, and assisted living facilities. They typically include both cooling and heating (electric or heat pump).
How They Work
Same principle as through-the-wall units but built to heavier commercial specifications. PTACs install in a standardized wall sleeve (42" wide is the industry standard) and include both a cooling mode and a heating mode — either electric resistance heating or a heat pump that reverses the refrigeration cycle.
Specs and Performance
| Specification | Range |
|---|---|
| Cooling Capacity | 7,000–15,000 BTU |
| Heating Capacity | 7,000–15,000 BTU |
| Efficiency (EER) | 9.0–13.0 |
| Noise Level | 45–55 dB |
| Power | 208V/230V |
| Typical Lifespan | 7–10 years (commercial), 10–15 years (residential) |
Pros
- Heating and cooling in one unit
- Standardized wall sleeve (easy replacement across brands)
- Individual room control
- No ductwork required
- Commercial-grade durability
Cons
- Noisier than residential options
- Less efficient than mini splits
- Industrial appearance
- Requires 208/230V power
- Higher cost than comparable window ACs
Best For
Hotels, motels, senior living facilities, hospitals, condos with existing PTAC sleeves, and commercial spaces needing individual room control.
7. Evaporative Coolers (Swamp Coolers)
Evaporative coolers work on a completely different principle than all other AC types. Instead of refrigerant, they use water evaporation to cool air.
How They Work
Hot, dry air passes through water-saturated pads. As water evaporates, it absorbs heat from the air, lowering the air temperature by 15–40°F. A fan then blows this cooled, humidified air into the space. Unlike refrigeration-based ACs, evaporative coolers add moisture to the air.
Specs and Performance
| Specification | Range |
|---|---|
| Cooling Capacity | Rated in CFM, not BTU |
| Airflow | 2,000–7,500 CFM |
| Temperature Drop | 15–40°F (depends on humidity) |
| Water Usage | 3–15 gallons/hour |
| Power Draw | 100–500 watts |
| Noise Level | 40–65 dB |
The Critical Limitation: Humidity
Evaporative coolers only work effectively when relative humidity is below 50%. In humid climates (Southeast U.S., Gulf Coast, most of the East Coast), they're virtually useless. They're designed for arid climates: the desert Southwest, mountain West, and parts of the Great Plains.
| Outdoor Humidity | Cooling Effectiveness | Best Regions |
|---|---|---|
| Below 20% | Excellent (30–40°F drop) | Arizona, Nevada, New Mexico |
| 20–40% | Good (20–30°F drop) | Colorado, Utah, parts of California |
| 40–50% | Fair (10–20°F drop) | Marginal — borderline effective |
| Above 50% | Poor to useless | Not recommended |
Pros
- 75–80% less electricity than refrigerant-based ACs
- Very low upfront cost (portable: $100–$500)
- Adds moisture in dry climates (beneficial)
- No refrigerants (zero GWP environmental impact)
- Fresh air ventilation (windows stay open)
Cons
- Only works in dry climates (below 50% humidity)
- Adds humidity (problematic in moderate climates)
- Requires continuous water supply
- Higher maintenance (pad replacement, mineral deposits)
- Less precise temperature control
- Requires open windows/doors for airflow
Best For
Dry climates with humidity consistently below 40%. Southwest U.S. homeowners. Outdoor cooling (patios, garages). Workshops and warehouses.
8. Hybrid / Dual-Fuel Systems
Hybrid systems combine an electric heat pump with a gas furnace, automatically switching between the two based on outdoor temperature. They're the most efficient option for year-round comfort in cold climates.
How They Work
Above a set "balance point" temperature (typically 30–40°F), the system operates as an electric heat pump — the most efficient heating method available. Below that temperature, it switches to a gas furnace, which is more cost-effective than a heat pump in extreme cold. The system automatically chooses whichever fuel source is cheaper at any given temperature.
Specs and Performance
| Specification | Range |
|---|---|
| Cooling Capacity | 18,000–60,000 BTU |
| Heating Capacity | 40,000–120,000 BTU (gas furnace) |
| Cooling Efficiency (SEER2) | 16–22 |
| Heating Efficiency (HSPF2) | 8–12 |
| Gas Efficiency (AFUE) | 80–98% |
| Typical Lifespan | 15–20 years |
Pros
- Most efficient year-round system for cold climates
- Automatic fuel switching optimizes cost
- Both cooling and heating
- Can qualify for federal tax credits (heat pump incentives)
- Lower operating cost than all-gas or all-electric systems
Cons
- Highest upfront cost ($5,000–$15,000 installed)
- Requires both gas and electric infrastructure
- Complex system with more potential failure points
- Requires professional installation and maintenance
Best For
Homeowners in cold climates (Northeast, Midwest, Mountain West) with existing gas lines who want year-round efficiency and comfort.
How to Choose the Right Type for Your Situation
Decision Matrix: Find Your Best AC Type
| Your Situation | Best AC Type | Why |
|---|---|---|
| Renter, single room, budget | Window AC | Lowest cost, no permanent install |
| Renter, HOA bans window units | Portable AC | No exterior visibility |
| Homeowner, no ducts, 1–3 rooms | Ductless Mini Split | Best efficiency, quiet, heating+cooling |
| Homeowner, existing ducts | Central AC | Whole-home cooling, best value with ducts |
| No suitable window in room | Through-the-Wall | Permanent, doesn't use a window |
| Hotel/commercial, room-by-room | PTAC | Standardized, heating+cooling, individual control |
| Dry climate (under 40% humidity) | Evaporative Cooler | 75% less electricity, adds beneficial humidity |
| Cold climate, year-round needs | Hybrid/Dual-Fuel | Auto-switches fuel for lowest operating cost |
Cost-Per-BTU Comparison
When comparing upfront cost across types, cost-per-BTU puts them on equal footing:
| AC Type | Cost/BTU Range | Example (12,000 BTU) |
|---|---|---|
| Window AC | $0.02–$0.04/BTU | $240–$480 |
| Portable AC | $0.03–$0.06/BTU | $360–$720 |
| Through-the-Wall | $0.04–$0.06/BTU | $480–$720 |
| PTAC | $0.05–$0.08/BTU | $600–$960 |
| Ductless Mini Split | $0.13–$0.35/BTU | $1,560–$4,200 |
| Central AC | $0.19–$0.40/BTU | Whole-home only |
Efficiency Comparison (Normalized)
Different AC types use different efficiency metrics, making direct comparison tricky. Here's an approximate conversion to common ground (annual operating cost for 12,000 BTU equivalent):
| AC Type | Efficiency Metric | Typical Value | Approx. Annual Cost* |
|---|---|---|---|
| Mini Split | SEER2 22 | 22 | $55 |
| Central AC | SEER2 17 | 17 | $70 |
| Window AC (Inverter) | CEER 14 | 14 | $85 |
| Window AC (Standard) | CEER 11 | 11 | $110 |
| Through-the-Wall | CEER 11.5 | 11.5 | $105 |
| PTAC | EER 10.5 | 10.5 | $115 |
| Portable AC | CEER 9 | 9 | $135 |
| Evaporative Cooler | N/A | N/A | $20–$35 |
At $0.168/kWh, 8 hrs/day, 125 days/year.
Key Takeaways
- Window ACs offer the best value for single-room cooling — lowest cost per BTU and easy DIY installation.
- Portable ACs are the least efficient type. Only buy one if you genuinely can't use a window unit.
- Mini splits are the most efficient AC type available. The higher upfront cost pays back in 4–8 years through energy savings.
- Central AC makes sense only if you have existing ductwork or are cooling 4+ rooms.
- Evaporative coolers are the cheapest to run by far, but only work in dry climates below 40% humidity.
- For renters: Window AC is almost always the answer. It's cheap, effective, and comes with you when you move.
- For homeowners: Mini split if you want the best long-term value. Central AC if you already have ducts.