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.
A note on names. This page is a portable AC size calculator, and it doubles as a portable AC BTU calculator, a portable air conditioner calculator or a portable air conditioner room size calculator. It is also a portable air conditioner size calculator, a portable air conditioner BTU calculator and a portable AC unit BTU calculator. For what size portable AC unit do I need, or how big of a portable AC do I need, the tool at the top gives one answer in SACC. The portable air conditioner BTU chart further down shows the same result as a table. That table is a portable AC BTU chart, a portable air conditioner sizing chart or a portable air conditioner room size chart. It lists the portable AC unit sizes sold with the portable AC room size each one covers.
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.
A common worry is that the second hose blows outdoor air, with its pollen and smells, into the room. It does not. That air passes over the hot coil and goes straight back out, and never mixes with the air you breathe. It is the single-hose unit that draws unfiltered outdoor air indoors, through every gap around doors and windows.
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, and 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. |
10000 BTU Portable Air Conditioner Room Size
The chart above reads in SACC. Most boxes still shout the larger ASHRAE number, so here is the room size for the box ratings people ask about. In 10000 BTU sq ft terms, a 10,000 BTU portable air conditioner covers about 265 sq ft as a single-hose unit and about 325 sq ft as a dual-hose one. That is far less than the 400 to 450 sq ft often printed beside it.
The other common sizes follow the same pattern. An 8,000 BTU box covers about 210 sq ft single hose and 255 dual hose. A 12,000 BTU box covers about 320 and 390 sq ft. A 14,000 BTU box, the size many people buy for a living room, covers about 375 and 460 sq ft. If the listing gives a SACC figure, use that with the chart and skip this conversion. The full table is in the SACC vs ASHRAE BTU guide.
Portable AC vs Window AC: Which Is Better?
For cooling a room, the window unit is better. It delivers all of its rated capacity, uses less electricity for the same cooling, and keeps its noisy parts outside. The portable AC wins on one thing only, and it is a big one: it can go where a window unit cannot. So the portable vs window AC question is really two questions. Which cools better, and which can you actually install? On portable air conditioner vs window unit, the window unit wins the cooling half, and the same is true of portable air conditioner vs window air conditioner or window unit vs portable AC. The difference between portable AC and window AC units comes down to the seven rows below.
| What You Compare | Window AC | Portable AC |
|---|---|---|
| Cooling from a 10,000 BTU box | About 10,000 BTU | About 6,300 BTU single hose, 7,700 dual hose |
| Room a 10,000 BTU box covers | 410 to 470 sq ft | About 265 sq ft single hose, 325 dual hose |
| Power for 8,000 BTU of real cooling | About 680 watts | About 800 watts |
| Where the compressor sits | Outside the glass | Inside the room |
| Window it needs | A double-hung sash, in most cases | Any window or wall port a hose can reach |
| Can the window still close? | No, not while it is installed | Yes, once the hose panel is lifted out |
| Floor space | None | A corner near the window |
The window figures come from our window AC size calculator and the portable figures from the calculator on this page, so both columns use one method. People also call a portable a floor AC, a standing AC, a stand up air conditioner or a freestanding unit. So floor AC vs window AC, standing AC vs window AC and stand up AC vs window AC are this same comparison under other names.
Portable AC vs Window AC Efficiency and Electricity Use
Are window air conditioners more efficient than portable ones? Yes, and the reason is where the machine sits. A window unit keeps its hot side outdoors. A portable keeps the whole machine in the room, so the compressor and the exhaust hose give heat back to the air you are paying to cool. A single-hose model also blows room air outside, and warm air leaks in under doors to replace it.
Which uses more electricity, a portable AC or a window AC? The portable. On portable AC vs window AC electricity consumption, our figures show a portable needs about 18% more power than a window unit to deliver the same cooling. At the 8,000 BTU level that is about 800 watts against 680. For 10,000 BTU it is about 1,000 watts against 845, and for 12,000 BTU about 1,200 against 1,015. At $0.17 per kWh the 8,000 BTU pair costs about 14 cents and 12 cents for each hour the compressor runs.
A dual hose portable AC vs window AC is a closer contest, because the second hose stops the unit pulling warm air into the room. It still delivers about 77% of its box rating where a window unit delivers all of it. Tip: for the same room, a portable has to be one or two box sizes larger than a window unit, and it will still cost more to run. For exact watts and amps at any size, use the AC wattage calculator.
Portable AC or Window AC: Noise, Water and Daily Use
Are portable air conditioners louder than window units? In most homes, yes. Owners who have had both tend to report the same three things. The portable is louder, because the compressor is in the room and not hanging outside. One owner wrote that he sleeps with ear plugs beside his. The hose gets hot, and several people ended up wrapping it in insulation to stop it warming the room. And a portable collects water inside its cabinet, so in a humid climate it either drains through a line or has to be emptied by hand.
The window unit has its own costs. It blocks the window for the season, it lets in more street noise because the sash is never fully shut, and it has to be lifted in and out. We do not print decibel numbers here because they differ by model and we have no measured set to quote. Compare the two spec sheets if noise is what decides it for you.
Should I Get a Window AC or Portable AC?
Are window AC units better than portable ones? For cooling, yes, so get the window unit if your window can take one and your lease allows it. You will buy a smaller size, pay less to run it and get a colder room. Is a portable AC better than a window AC in any case? It is, in four. Get the portable if the window slides sideways or cranks outward, if the building bans window units, if you need to close and lock the window at night, or if you want to move the cooling from one room to another. The list of cases where a portable is the right pick, higher up this page, covers the rest. Whether you frame it as portable AC versus window AC, portable AC unit vs window AC unit or portable AC units vs window units, the window decides.
Tip: if a window unit fits, buy the window unit. If it does not, buy a dual-hose portable sized by its SACC rating, not by the number on the front of the box.
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 neighboring 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, then price it with the mini split cost 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. Tip: if it has a compressor, it needs somewhere to put heat, and no marketing gets around that.
Window AC Unit With No Window
This one gets its own answer, and it is a short one. 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.