Which is Quieter: Portable or Window Air Conditioner?

When considering buying a window or portable air conditioner, which is quieter when running and what is the difference in noise levels produced by typical models of each type?

It is commonly believed that because of the way they are, portable coolers tend to make more noise than window units.

However, when comparing similarly powered portable air conditioner vs window air conditioner models, a surprising result became evident.

Let's take a look at each type of cooling appliance and see if commonly held views are correct, or if there are some surprises in store!

Portable Air Conditioner Noise Levels

The noise levels produced by most AC units is generally not too high as is often believed.

However, get the wrong unit and it can produce more than 60 decibels, making it difficult to sleep in a room with such a loud AC unit.

It is of course important to find a portable AC that is as quiet as possible to make it easier to sleep at night as well as not be disturbed during the day when you're at home.

A reasonable level should be around 55 decibels or less. This is often achieved at the lowest speed setting for many units, but generally, as more cooling power is required more noise is produced.

Which Portable AC Unit Parts Produce the Most Noise?

window ac vs portable acTwo primary generators of noise are present in portable air conditioners. These are:

  1. Airflow
  2. Compressor

A decibel meter reading portable air conditioner compressors can jump to over 70 dB. As you can see, high airflow will create a swirling sound as it travels through the AC unit.

There are more efficient dual hose, self evaporating portable AC units that produce better cooling for lower compressor overhead, resulting in slightly lower noise levels.

However, for quietest running, an AC should have both low airflow and a quiet compressor to ensure it is quiet enough to be unobtrusive when operating.

Let's look at four simple attributes of a quiet room AC conditioner:

Low Airflow, Colder Air Portable AC Units Generate Less Noise

The airflow through the portable AC creates a swirling sound. The portable air conditioning unit will get louder if it cools faster. This is because of the increased airflow.

Also, you know that larger 14,000 BTU portable AC units are louder than smaller 8,000 BTU units. It's because a 14,000 BTU unit must create more airflow. While there are many other factors, reducing HVAC unit airflow will reduce overall noise levels.

It is preferable to have low airflow. Airflow simply refers to air moving through an AC unit. The faster it is, the higher the decibels it will produce.

There are two types of portable air conditioners in terms of airflow:

An Example:

Two different portable AC units of 14,000 BTU each are used to set the room temperature at 72°F. The first unit will blow 68°F air and 400 CFM airflow. The second unit will blow 64°F air with 200 CFM airflow.

Cooling effect will remain the same (14,000 BTU); what about noise levels? Which portable air conditioner is quieter?

The second unit will be quieter in all cases due to the lower airflow.

In general, units with the lowest airflow produce quieter portable air conditioners.

The compressor is the second noise generator for portable AC units. It lowers the temperature of the output air.

Compressor Type

There are two types of compressors.

  1. Rotary compressor. This is the standard version that can be found in portable air conditioners
  2. Inverter compressor. This is the advanced version found in portable air conditioners with low noise levels

We won't get into the internal workings of compressors. This is the key difference between portable air conditioning devices and compressors.

Rotor compressors can make a lot of noise. Inverter compressors offer a low-noise upgrade.

A rotary compressor can be described as a turn-on-off compressor. Most fridges also have one. If you set your fridge to 35°F, the temperature will be between 32°F - 38°F.

The rotary compressor will activate (that produces that particular high-noise sound thump), and push the temperature down until it reaches 38°F. After this, it will then turn off.

The portable air conditioner's rotary compressor operates in the same manner. You set the temperature and the compressor kicks in from time to time, making a loud, high-pitched noise. This sound may wake you up if running overnight, so it is not ideal.

Inverter compressors, on the other hand, use a variable frequency drive with varying input voltages and frequencies to modulate compressor speed and adjust the cooling capacity more closely.


Fridge. If the temperature is 35°F, the inverter compressor will provide constant cooling power to maintain the temperature at 35°F. It will fluctuate between 34°F to 36°F, but it will do this very quietly.

An inverter compressor (silent), is better than a louder rotary compressor (louder).

Refer to Specification Sheet for Noise Levels

Each portable air conditioning appliance comes with its own specification sheet. However, not all specification sheets include noise levels.

If the noise levels can be measured, you can simply look at the decibels that this or that portable AC produces and rank them from the quietest to loudest.

Here are four common examples of how AC noise levels can be specified on a specification sheet found on the packaging of a portable AC unit:

  1. Noise levels: 51/55/59 dB (low/mid/high)
  2. Noise levels: 51 dB (low), 59 dB (high)
  3. Noise levels: 59 dB
  4. Noise levels not noted in specification sheet

The first example is what you want. Portable AC units come with three running speeds: Low, Medium, and High. A decibel measurement is required for each speed to be reliable.

Although the 2nd and 3rd examples don't give much insight into how quiet an AC unit can be, they do provide a reasonable guide.

The fourth example should be considered a red flag. If the noise levels of a portable air conditioner is not stated, the chances are either:

Portable air conditioner manufacturers that do not include noise levels (measured as dB) on their specification sheets should be avoided. This is a sign that you should be wary of portable ACs with spec sheets that omit this metric.

It is impossible to know how loud or quiet the unit is if it is not stated on the box or in the literature. The inference from this should be that these units are generally louder.

Size (BTU), EER Rating and Reliability

Portable air conditioners should be quiet, but they should also have a high-quality build to be considered the best or most effective portable AC unit. This is where cooling metrics are important.

The cooling effect is measured in British Thermal Units. You will need a larger portable air conditioner than you actually need. As we all know, louder units are more likely to be used due to greater airflow.

EPA recommends 20 BTU per square foot. This means that for 500 square feet of cooling space, a 10,000 BTU portable AC unit may be sufficient. To be safe, you can choose a 12,000 BTU unit.

However, it is best to not go above 15,000 BTU units as they will generate unnecessary decibels.

EER rating is the most important metric in choosing the quietest portable AC unit. EER is an acronym for Energy-Efficiency Ratio.

An AC unit with an EER rating above 8.5 will produce a lot of electricity savings over the long-term.

Window Air Conditioner Noise Levels

Air conditioners are a must-have appliance in your home, especially in summer when the temperature rises to uncomfortable levels.

You might need one around the clock to keep your home cool. It is possible to use the air conditioning while you sleep, but it would be a good idea to get one of these quiet window units.

These AC units are silent and have many other features that we've already discussed. There is more to AC units than you might think.

You need to take into account many things before purchasing one. Below is a buying guide for quiet window AC units. This guide will cover all the key factors that affect window air conditioning units for casement windows as well as other window configurations.

Cooling Capacity

It is important to ensure that your air conditioner can cool down properly before you buy it. AC units, even window models, all have cooling capacities.

This is simply a measurement of the AC unit's performance in BTU. Most models have a cooling capacity between 5000 BTU and 8000 BTU. However, some models can go up to 15000 BTU which should be sufficient for most users.

Noise Level

It is important to check the noise output rating of a particular window AC model you intend buying.

The rating is in dBA (decibels) and can from around 50 dBA to 60 dBA depending on which AC unit you choose. Typically, a more powerful unit (depending on its BTU rating) can run at a higher noise level than a more modestly powered unit.

The AC unit with a lower noise level (50 dBA) is generally the more quiet model, although this will depend on a number of factors as covered in the paragraphs above on portable AC units.

A low noise output is a great option if your AC needs to run while you sleep.

Area of Coverage

It is important to choose the AC unit that best suits the size of your space, as different rooms have different cooling capacities.

Although you can get an idea of the cooling capacity rating, it might not be the best option for all users.

You will find the coverage area rating for most AC units. This is simply the area that an AC unit can cool. There are different ratings for coverage, such as 200 or 350 square feet.

Larger rooms will benefit from a higher power rating, but may run at higher noise levels.

Energy Consumption

The air conditioner in your room runs on electricity just like other appliances. It is important to check the power consumption of your window AC conditioner.

This will ensure that your power bill doesn't increase excessively after you use an AC unit 24/7.

You can see the power consumption rating for most window ACs as 600 watts or 800-watts. A lower rating is more efficient.

You can also find ACs that are Energy Star certified, which generally have low power consumption.

Fan Power

Your air conditioner must provide a powerful enough cooling system for your needs and the size of the area it is intended to cool. The power rating of fans is also very important.

Fans with a good airflow are essential for proper cooling your room. You can find the fan motor power rating in HP, such as 1/3 HP or 1/2 HP depending upon which model you have.

A 1/2 HP rating is the best option in terms of fan power. You can also find the airflow rating on most air conditioners.

You can choose from 200 CFM or 300 CFM. A higher rating means better airflow.

Controls and Cooling Modes

An air conditioner is designed to cool your home. However, there are still cooling modes and controls that you can use.

These controls are very important to ensure you have control of your air conditioner.

You can change the fan speeds by using either 3 or 5, or a variable fan speed dial. You can also adjust the temperature of almost all AC units. This allows you adjust the temperature in your room to suit your needs.


There are many types of AC units available, each with different forms and features.

Window air conditioners are a popular choice because they offer low-cost performance and high quality.

Portable air conditioners are also popular because they offer portability, flexibility and a lot of choice in stores.

However, as to the question of which type is quieter when operating, the answer is inconclusive. Both types produce similar noise levels when units of similar power output were compared, with the quietest models producing as little as 49 dB and noisier units producing in excess of 60 dB.

The best way to know if the model you end up with will be quiet enough so as to not be a disturbance is to check the manufacturer's dB rating as a guide. The lower the dB rating, the quieter the unit is likely to be.

If this information is not available, chances are the unit will make more noise than you might prefer and should be avoided.

Posted: April 15, 2022

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