What Size Portable Air Conditioner Do I Need?
To figure out what size portable air conditioner you need, you first have to calculate your room's cooling load in BTU, and then match that load to a portable AC's DOE / SACC BTU rating. Unlike traditional window units, you should never just match your room size to the large ASHRAE BTU number printed on the box, or you may end up with an undersized unit.
Why Portable AC Sizing Is Different
Window AC and split AC ratings are easier for shoppers to compare directly. However, portable ACs lose efficiency because the entire unit, including its heat-generating components, sits inside the room. Furthermore, many single-hose models create negative pressure, pulling warm air back into the room from gaps around doors or windows.
That is why portable buyers should care more about SACC (Seasonally Adjusted Cooling Capacity) than big ASHRAE numbers. SACC is used by the DOE to represent a portable air conditioner's true capacity.
How This Portable AC Calculator Works
Like our main AC room size calculator, this tool starts with your room's square footage and ceiling height. It then adjusts the cooling load based on your local climate, sun exposure, insulation, number of occupants, and appliance heat.
The difference lies in the final recommendation: instead of matching the room to old-style portable ASHRAE BTU numbers, we match it to DOE / SACC BTU, which is a more realistic real-world shopping guide.
DOE / SACC vs ASHRAE BTU: What's the Difference?
Many portable air conditioners still show a large ASHRAE BTU number on the box, but that is not the best number for real-world sizing. For instance, a portable model once listed at 14,000 BTU under the older ASHRAE rating may now carry a 10,000 BTU DOE rating. That lower DOE/SACC number is not a weaker machine; it is simply a more realistic representation of how much cooling the unit actually delivers in practice. Always shop by SACC first! For the full story - what each test measures, why ratings dropped by half, and a conversion table for common sizes - read our SACC vs ASHRAE BTU guide.
Single-Hose vs Dual-Hose Portable ACs
If you must buy a portable air conditioner, a dual-hose design is often the safer choice for demanding rooms. Single-hose units can create negative pressure by exhausting indoor air outside, which allows warm air to leak back in through gaps and doors. Dual-hose systems reduce that problem by using separate intake and exhaust paths. If your room is very hot, sunny, or poorly insulated, our calculator will actively recommend a dual-hose unit.
When a Portable AC Is a Good Choice
- You live in an apartment or HOA with strict window restrictions.
- You have casement, slider, or unusually shaped windows.
- You need temporary cooling for a few weeks a year.
- You are renting and cannot install a permanent split system.
- You only need to cool a single room like a home office.
When a Portable AC May Not Be the Best Choice
Portable ACs are often the fallback option when a window unit or mini-split is not possible. If you are cooling an RV or camper rather than a room, those take a dedicated rooftop unit instead — our RV air conditioner size calculator sizes those. If a window unit is actually an option for your room, our window AC size calculator will size one, and at the same BTU number it will usually cool better than a portable for the reasons above. If a ductless unit is actually an option for your room, our ductless mini split calculator will size one properly. However, they may not be ideal if:
- The room is very large or has an open floor plan.
- The room gets heavy afternoon sun or is on the top floor.
- The house is leaky or poorly insulated.
- The climate is very hot and humid.
- You want the quietest and most efficient cooling possible.
How to Read Your Portable AC Result
When you use the calculator above, focus on the Recommended Portable AC Size (DOE/SACC BTU). We also provide a rough Ton Equivalent for reference, and estimated ASHRAE numbers if you are looking at a box that only lists ASHRAE. Pay attention to the "Preferred Type" field to see if a dual-hose unit is strongly recommended for your specific conditions.
Portable AC Buying Tips
- Always check SACC first: Look for the Seasonally Adjusted Cooling Capacity in the fine print.
- Seal the window kit: Use weather stripping to ensure no warm air leaks in around the exhaust hose panel.
- Keep hoses short and straight: Exhaust hoses radiate heat. Keeping them short and untangled improves efficiency.
- Close curtains and blinds: Sun exposure adds massive heat load; block it before it enters.
- Consider inverter models: If your budget allows, inverter portables are generally quieter and more efficient.
Portable AC Size Chart: Room Coverage by DOE / SACC BTU
Note: These are rough baseline portable AC estimates under standard conditions and should not be used as the final recommendation. Use the calculator above for climate, ceiling height, insulation, sun exposure, occupants, and appliance heat.
| DOE / SACC (BTU) | Room Coverage | Typical Room |
|---|---|---|
| 5,000 BTU | Up to 210 sq ft | Bedroom, home office, nursery |
| 6,000 BTU | 215 – 250 sq ft | Large bedroom, small studio |
| 7,000 BTU | 255 – 295 sq ft | Studio, small living room |
| 8,000 BTU | 300 – 340 sq ft | Living room, open kitchen-diner |
| 9,000 BTU | 345 – 380 sq ft | Open living area |
| 10,000 BTU | 385 – 425 sq ft | Large open living area |
| 12,000 BTU | 430 – 510 sq ft | Whole small floor, open plan |
| Over 12,000 BTU | Over 510 sq ft | No single portable is made this large. See window AC sizing or mini split sizing. |
Portable AC With No Window: What Actually Works
This is the most common reason people end up on a portable air conditioner in the first place, and it comes with a misunderstanding worth clearing up immediately. A portable air conditioner is not a no-window air conditioner. It still has to put heat somewhere, and that somewhere is outside the room.
Every single-hose unit works by pulling room air across a hot condenser and blowing that heat out through the exhaust. Remove the exhaust path and the unit becomes a heater with a fan on it, because the compressor generates more heat than the cold side removes. Running one unvented in a sealed room makes the room warmer, not cooler.
So the real question is not whether you can cool a room with no window. It is where the hose can go.
AC for a Room With No Windows: The Five Real Options
- Vent through a drop ceiling. Common in offices and basements. The hose goes above the tiles into the return plenum. Works, and it is often the least disruptive route.
- Vent through an interior door or wall. Pushing hot air into an adjoining space cools the small room at the expense of the larger one. Acceptable when the neighbouring space is a hallway or garage, poor when it is the room you also occupy.
- Vent through a dryer vent or wall port. A permanent 5 or 6 inch wall penetration works well and looks tidier than a hose in a window. It needs drilling, which rules it out for many renters.
- Ductless mini split. The proper answer. It needs only a three-inch hole for the line set rather than a window, which is precisely why it exists. Size one with our mini split size calculator.
- Accept that it is not air conditioning. An evaporative cooler or a fan moves air and can help in dry climates. Neither removes heat from a sealed room, and no product does without an exhaust path.
Portable AC Without a Window Vent: The Products That Claim to Do It
Two categories market themselves at this problem and neither is quite what it appears.
Evaporative coolers, often sold as portable air conditioners, add moisture to the air and lower its temperature by evaporation. They need no exhaust because they remove no heat. In a dry climate they genuinely help; in a humid one they make a warm room into a damp warm room.
Ventless or hoseless portable air conditioners are almost always evaporative coolers under a different name. If a listing promises real refrigerant cooling with no exhaust of any kind, the physics does not support it. The rule: if it has a compressor, it needs somewhere to put heat, and no marketing gets around that.
Window AC Unit With No Window
Worth answering separately because people search it, and the answer is shorter. A window unit needs to straddle the boundary between inside and outside, with its condenser in open air. Mounted indoors it dumps its own heat straight back into the room. The only variant that works without a window is a through-the-wall sleeve, which is a different product designed for a permanent wall opening, and installing one means cutting the wall.