29 Factors to Consider when Buying a Portable Air Conditioner

With so many features, functionality, and ratings, it can be quite overwhelming trying to figure out the best portable AC for your needs. What follows is a comprehensive guide explaining all the product attributes you will find in the portable AC technical specifications. 

1. How much power do you need from a portable ac?

Portable AC cooling performance is measured in British Thermal Units (BTUs). A BTU is a measure of how much energy it takes to heat water which doesn’t make a lot of sense for air conditioners. However, since air conditioners remove heat from the air and circulate cool air back into the room, the BTU measurement still works. Instead of measuring the amount of heat added to the air in your home, they measure how much heat is removed. Just like with heaters, the higher the BTU rating of an air conditioner, the more powerful it is.

As a rule of thumb, you will need at least 20 BTUs per square foot of living space you want to cool. For example, a 400 square foot room will need a portable air conditioner rated at a minimum of 8,000 BTUs. We recommend going with more power especially if you live in a part of a country with high humidity and if the outside temperatures are particularly high. Use our BTU calculator to calculate the right performance for your room size. 

There are two standards organizations that measure the BTU performance for air conditioners. The first is the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), a society that funds research into advancing heating, ventilation, air conditioning and refrigeration (HVAC&R) systems design and construction. The second is the United States Department of Energy (DOE). 

The DOE ratings are typically a lot lower than those measured by ASHRAE. We’re not sure why. From our testing, we recommend going somewhere in the middle as the ASHRAE ratings tend to be on the high side and the DOE ratings tend to be quite conservative. If a portable AC is rated at 10,000 BTUs by ASHRAE and 5,500 BTUs by the DOE, we would assume this model is capable of cooling a room measuring between 300 and 400 square foot room depending on humidity levels and ambient heat (room heat before cooling). 

2. What is the Energy Efficiency Ratio (EER)?

The efficiency of a portable air conditioner’s efficiency is measured by the energy efficiency ratio (EER). The EER is the ratio of the cooling capacity (in British thermal units [Btu] per hour) to the power input (in watts). If you plan to run a portable AC for long periods of time over a hot summer, you’ll want an ac unit with a high EER rating as your energy costs will skyrocket with an inefficient model. Obviously, more powerful portable ACs use more power so be careful to purchase one with the right BTU output for the square footage you want to cool. Buying one that is more powerful than your needs, will simply result in wasted energy and higher energy bills.  

For more information on Energy Efficiency Ratios, see this excellent article written by R. Scott Frazier, a professor at the University of Oklahoma: Understanding Energy Efficiency Measures for Heating and Cooling Systems

3. Are portable air conditioners safe to use? 

All electrical appliances can pose a threat of fire or electrocution. To ensure owners’ safety, there are standards boards that test the equipment to ensure compliance with safety standards. Portable air conditioners are certified by Intertek’s ETL certification program or through UL Standards. Check the manufacturer’s information to see if the portable AC you are considering has been approved by either ETL or UL.

4. Can I control the portable AC from an app on my phone? 

New smart home devices make it possible to control your home temperature via an app. Smart home thermostat solutions like Nest are extremely handy in helping reduce your energy bills. They also offer the convenience of turning on your air conditioner before you plan to be home so you return to a nice cool home. A few portable air conditioners now offer this option though it’s not yet common. We expect to see more on the market over the next year or two. 

5. What does CFM mean and why is this important? 

CFM stands for cubic feet per minute (also referred to as airflow). CFM is basically how much air a fan moves in one minute. CFM measurement is done when a fan is at its highest speed and factors in both the volume of air moved and the rate at which it moves. The higher the CFM rating, the more air a fan will move in a minute of time.

Most portable air conditioners are equipped with a powerful fan, powerful enough to circulate the cool air around a room. Some manufacturers provide the CFM rating, others don’t. You’ll want to check to see if the CFM rating is over 200 for an average sized room (approximately 400 square feet). 

6. Does the portable AC come with an installation kit?

Almost all portable air conditioners come packaged with an installation kit which consists of a window seal with a pre-fit opening into which you will insert the vent hose (or two hoses if you choose a dual-hose model). The window installation kits fit sliding windows but may not be compatible with casement windows, windows that open using a crank handle or certainly won’t work if you plan to vent the portable AC unit out the door. For casement-style windows, you may need to purchase a low-cost seal such as this one available on Amazon: Sunkong Window Seal for Mobile Air Conditioners. There are also option for door seals such as this one available on Amazon: Vodche Zipper Screen Door Seal for Portable Air Conditioner.

7. Will the installation kit fit my window?

Carefully measure the openings of any windows for which you plan to install the window installation kit. Manufacturers will provide the minimum and maximum window sizes for the ac unit installation kit. Some units will fit window openings as small as 19 inches while others will require a larger window opening.

8. Are portable air conditioners compatible with sliding windows?

Almost all portable ACs come with installation kits that are sliding window compatible but it’s worth checking to make sure.

9. Do portable air conditioners come with a remote control?

Almost all residential portable ACs come equipped with a remote control these days. However, it’s best to check to make sure as there may still be some models that don’t. You’ll appreciate the convenience of a remote control especially if you’re using the unit in your bedroom at night.

10. Are programmable timers standard on portable air conditioners?

Programmable timers are typically included as a standard feature in residential portable air conditioners. They are not usually present on commercial models.

11. How big are portable air conditioners?

Portable air conditioners come in various sizes with lower power models typically smaller in size than the more powerful ones. The portable ACs we’ve reviewed range in width from 15 to 20 inches, height from 29 to 34 inches, and depth from 14 to 19 inches.

12. How heavy is a portable air conditioner?

If you’re planning to move the portable AC from one room to another, you’ll want to pay attention to the unit’s weight. Some portable ACs can be very heavy and though most come equipped with rolling castors, if you have to lug it up stairs, you’ll want to know to know that that is possible. Most portable ACs weigh in at a back-breaking 60 lbs or more!

13. What is the difference between a single hose portable AC and a dual hose model?

Portable ACs can come with one or two air hoses. Single hose models draw air from inside the room, cool and recirculate some of the air, and expel warm air via the vent hose through the window. This can create a negative air pressure effect where the vacuum created in the room will suck warm air in from other areas, through gaps in doors, ceilings, etc. Dual hose portable AC units eliminate the negative pressure effect by drawing air in from outside with one hose, cooling it, and blowing the cool air into the room while also drawing warm air from the room and expelling it via the second hose. Dual hose models are more efficient but come at a higher price.

14. What does drain hose compatible mean?

Most portable air conditioners include an option to attach a permanent water drain hose to allow collected water to drain out to a floor drain. If this is a feasible option, it eliminates the needs to manually drain the water by emptying the water bucket or tray.

15. What is a self evaporating portable air conditioner?

A portable air conditioner draws in warm air from the room, compresses it, and blows cold compressed air back out. A byproduct of this process is water. Water is produced because the ac coils are at very low temperature and when air is cooled by the coils, the moisture in the air condenses. Standard portable air conditioners come with buckets or trays to catch the water and they need to be periodically emptied. If you live in a humid climate, you’ll find yourself emptying the bucket quite often.

Self evaporating portable AC units use technology to recycle the moisture to cool the ac coils making these models more efficient as well as reducing the manual effort required to drain the tray or bucket. Some models are partially self-evaporating and still require you to empty the tray or bucket and others are fully self-evaporating, meaning that you never have to manually drain them. Fully self-evaporating models exhaust the remaining moisture through the hose and out of the window.

16. What is an internal condensate pump?

Some portable air conditioners come with an option to add a condensate pump. Condensate pumps are used in conjunction with drain hoses, they help remove the water buildup from the ac unit. If you don’t have the option to drain the water through the drain hose to your plumbing system using gravitational force, you might need an internal condensate pump to expel the water through a window or up and out of a sink.

17. What is a full bucket indicator?

Full bucket indicators tell you when your portable air conditioner’s water bucket or tray is full and needs to be drained. When the bucket or tray is full, the full bucket indicator will automatically shut off the device to prevent water overflow which could damage the ac unit or your home. If you plan to run a portable air conditioner for long periods, including when you’re not at home, you’ll want to make sure you buy a model that has a full bucket indicator with the auto shutoff feature.

18. Do I need heat and fan only modes?

Most portable AC units include fan only mode which will keep the air circulating but not actively cooling the room. This is particularly useful if the AC unit has an integrated air filter as it will keep removing pollutants and allergens from the room even when the room is at your desired temperature. Some models also include a heat mode, turning the appliance in a dual-functioning heating and cooler appliance. If you plan to use the portable AC unit in a room that also gets cold in the winter months, this could prove to be a useful feature eliminating the need to purchase a separate space heater.

19. What is automatic mode on a portable air conditioner?

Automatic mode allows you to set a desired temperature and the ac unit will cool the room until the desired temperature is reached at which point it will automatically switch to fan only mode. This helps improve the overall energy efficiency and reduces the need to manually switch between cooling and fan only modes or turning the device on and off.

20. What is dehumidifier mode and do I need it?

All portable air conditioners remove moisture from the air as part of the cooling process. This is why you have to either drain water from the unit manually or via a drain hose unless you buy a fully-evaporating model. Most models also include a dehumidifier mode where the unit will work only as a dehumidifier, useful for people who live in humid climates when you might not need to cool the room but you want to reduce the humidity.

To use the device in dehumidifier only mode, you will have to disconnect the exhaust hose so the air returns to the room. Dehumidification capability is measured in moisture removal per hour (pints). If you need a dehumidifier, compare the capability of a portable air conditioner with that of a dedicated dehumidifier.

21. Do portable air conditioners include air filters?

All portable air conditioners include air filters to clean pollutants and allergens from the air before recirculating it back into the room. Look for models that have washable air filters to avoid the need to buy replacement air filters. Some models may also use high-efficiency particulate air (HEPA) filters that work well for removing allergens.

22. How loud are portable air conditioners?

Most modern portable air conditioners are fairly quiet with a maximum (at full power) noise level of under 60 decibels (dB). Running the AC unit at below full power will result in lower noise levels. Of the models we reviewed, the maximum noise range was between 49 dB and 59 dB. For a comparison of that means check this handy noise-level comparison chart provided by Yale University: Decibel Level Chart

23. What are the minimum and maximum thermostat settings?

All of the models we reviewed have a minimum thermostat setting of 61 degrees Fahrenheit with a maximum setting of 89 degrees Fahrenheit.

24. What is the operating temperature range of a portable air conditioner?

The operating temperature range is what the manufacturer claims to be the minimum and maximum temperatures at which the portable AC unit is effective. The lowest temperature range will depend on whether the unit can also be used as a heater. The highest temperature we have seen is 100 degrees Fahrenheit but this will also be impacted by humidity levels. We do not believe any portable air conditioner will be particularly effective if the room temperature is in the high 90s with high relative humidity.

25. What is automatic restart on a portable air conditioner?

If there’s a power outage, the auto restart function restarts the AC unit with the previous settings when electricity is restored.

26. What are adjustable louvers?

The louvers on a portable air conditioner are the slats on the air vent through which the cool air blows into the room. Adjustable louvers allow you to set the direction of the air flow.

27. What is automatic oscillation?

Automatic oscillation refers to the louvers. Turning on automatic oscillation will help improve air circulation and increase the effectiveness of cooling the room.

28. Why should I be concerned with the wattage, amperage, and voltage ratings when choosing a portable air conditioner?

All air conditioners take a lot of power to run, especially when run at their maximum cooling settings. High wattage AC units will obviously be more costly to run. You’ll also want to make sure that the AC unit doesn’t overload your home’s electric circuits which could happen if you’re running the portable AC at the same time as using other high-energy appliances. If you live somewhere that is prone to power outages and want to run the AC unit off a backup generator, you’ll need to check that your generator has sufficient power to run the unit. Portable AC units range in maximum wattage from 800 to 1600 (more for commercial portable ACs) with amperage ratings between 8 and 12 amps. Almost all residential models run off standard 120 volts.

29. How much does a portable air conditioner cost?

Portable air conditioners designed for home use cost between $400 and $800 depending mostly on power output and also features. Commercial portable ACs cost significantly more with some high-end models costing over $10,000.

Buying a portable air conditioner

Now that you’re armed with the information you need to make an informed buying decision, see our detailed buying guide to portable air conditioners here: 10 Best Portable ACs for Home Offices, Bedrooms, and Dorm Rooms.