Single Stage vs Two Stage Air Conditioner – In-depth Comparison 2021

| Last Updated: May 3, 2021

So, it’s time to invest in a new air conditioner for your home. Maybe your current air conditioner is showing signs of disrepair and you have been searching for the best replacement. If so, you have probably come across single-stage air conditioners and two-stage air conditioners.

If you have never thought about air conditioners before, you will probably have quite a few questions about these like what the differences are between them and the pros and cons of both. 

There is no need to worry about these questions anymore as we have put together this article to help you understand the differences, similarities, benefits, and negatives of single-stage and two-stage air conditioners. We are going to answer all of your burning questions on these air conditioners so you can make a confident final decision on which one you want. 

In a hurry to get a new air conditioner? Let’s have a look at these two types of air conditioners right away!

Differences Between a Single-Stage and Two-Stage Air Conditioner

Both systems accomplish the same task, so what's the difference?


There are a few differences between the single-stage and two-stage air conditioners but the main difference is the type of compressor each uses. The compressor is a component of the air conditioner that compresses the refrigerant. 

Single-stage air conditioner compressors work at only one level of operation. This cools your home considerably on full blast. 

On the other hand, two-stage conditioner compressors work at two levels of operations. One is for those humid and hot summer days which is like the full blast of a single-stage air conditioner and the other operates lower for milder days when you don’t require too much cooling.

Two-stage air conditioners typically run on the lowest setting until the temperature rises outside and you require more cooling. At this point, it starts to run on a high setting to keep you cool and comfortable.


Two-stage air conditioners are generally more expensive than single-stage models. The main reason for this price difference is the internal components within both cooling systems.

As we have discussed, the fact that two-stage air conditioners contain a compressor that runs at two speeds means it is more versatile and useful in different climates.


On the whole, air conditioners have one job and that is to adjust your home’s temperature by a few degrees. Single-stage air conditioners turn on at 100% and then cool your home for a few minutes before shutting off again. As soon as the temperature falls below the thermostat setting which you set, this cycle is repeated once again.

Short cycles such as these are not the most beneficial to your system’s efficiency. Going on and off repeatedly isn’t the best way of cooling your home for long periods. It’s like turning off a car’s engine every time you stop and start it again as soon as you have to move. This isn’t only inefficient but it’s also a waste of time and money.

Fortunately, there is no such problem with the two-stage air conditioning system. These can run smoothly and achieve your cooling requirements around 80% of the time because of their lower settings and limited starts and stops.

Instead of running at 100% for short periods of time, these models cool your home at slower speeds for longer periods.

It’s hard to fathom but although two-stage air conditioners run for longer, they will save you money on your energy costs over time.

Nonetheless, you can alter the settings if required by running a two-stage air conditioner at 100% capacity for those sweltering, hot summer days.


Air conditioners are made to make you feel more comfortable in your home or whatever space you are in. Because two-stage air conditioners run more efficiently and for longer periods, this helps your home’s temperature become more comfortable. This happens because the air conditioning fan will be running more, therefore circulating air throughout your home for a longer time. This helps rooms cool evenly and prevents most hot or cold spots around your home.

Variable Speeds

Although two-stage air conditioners offer increased efficiency and comfort, it is still possible to improve these aspects with a variable speed air handler. These fans operate similarly to two-stage air conditioners by moving at different speeds resulting in significant energy savings. Some air conditioners can also be quite noisy but the slower the fan rotates, the quieter your whole system will operate.

As we stated, two-stage air conditioners will set you back more money at first but over time, they will help you save money on energy bills and make up the difference of the initial cost in a short amount of time.


You should consider the size of each air conditioning unit. Single-stage air conditioners are typically much smaller than two-stage ACs. If you live in a home with a smaller floor plan, you may be better off getting a single-stage air conditioner as the two-stage models can take up a lot more space. Also, single-stage air conditioners generally have fewer interior components and electrics so repair bills could be a little lower if anything goes wrong. They may not be as energy-efficient but if you won’t be using one every day, a single-stage air conditioner could be more than enough for you and your needs.


Installation costs can vary depending on who you hire or if you install the AC yourself. Nonetheless, it is highly recommended that you hire a contractor to install a single-stage or two-stage air conditioner. These will give you a wide range of AC prices as well as which ones have the best warranty. As with any appliance, air conditioners can become faulty so a warranty is important. Without a warranty, you could be facing large bills to fix the AC or even buy a new system. A warranty will leave you safe in the knowledge that if anything does go wrong, you are covered.

What is Best to Choose?

This is the main question most people ask when thinking about air conditioners. Which is better? The air conditioner for hot, humid summer days or the AC built for milder climates? There are a few factors to consider here.

If you want to choose an air conditioner for hot days, you need to think about when it isn’t that hot such as the nighttime.

As temperatures cool during the evening and night, your home will also cool off. Meanwhile, the air conditioning unit will not run long enough to remove all the humidity. This means that you will have to lower the thermostat quite often just to feel comfortable in your own home. 

On those hot days, your unit will be the ideal size and run at the right times to cool and dehumidify efficiently. On the other hand, on milder days, the unit will turn on and very quickly discover it isn’t needed and will turn off again leaving your home muggy and uncomfortable.

Ideally, it should be possible to have one air conditioner that works well on very hot days as well as milder days. Of course, these would cost a fortune and be very difficult to maintain. Thankfully, there is a machine that is powerful enough to work on hot summer days and then power down on milder days. This is, of course, the two-stage air conditioning system.

Standard air conditioners are all single-stage units so always work at full blast or full power. Two-stage systems have several power settings to provide you with the perfect amount of cooling, no matter what the temperature is outside. 

As we have discussed, two-stage air conditioning units work on high for hot summer days and low for milder days. You get greater control over your home’s humidity while using much lower levels of energy. You will always benefit from even temperatures throughout your entire home.

It is important to choose the right air conditioner for your needs and the temperature you experience most.

Choosing an inferior air conditioning unit will increase your energy bills and leave you feeling uncomfortable in your own home.

The two major factors you need to consider are:

  • Your budget
  • Where you live and its climate

Think about what you can afford today. If you have a tighter budget at the moment, a single-stage AC is the better option as its initial costs are somewhat less. However, you can get financing for two-stage air conditioners if you are dead set on what these have to offer.

Where you live is important as areas with high humidity will benefit most from two-stage air conditioners. 

In Summary

Finding a good quality air conditioner can be the difference between uncomfortable humid months and comfortable, cool days. Air conditioners help your home feel cool and inviting throughout long hot days and nights.

As we have seen, two-stage air conditioners will save you money in the long run. Milder climates will benefit from these units as they run at a slower rate, leaving your whole home with an even temperature. Single-stage air conditioners will cost less at first but the fact that they go on and off frequently will leave you out of pocket over time.

You must find an AC unit that lowers your energy bills and keeps your home at a comfortable temperature. With this in mind, the two-stage air conditioning unit is the best choice.

My name is Bob Wells and I am a retired HVAC tech from Washington state. I am currently retired and no longer do much with HVAC, however, I feel like I have a lot of knowledge in the subject and I wanted to create a website where I could talk about what I've learned and help upcoming HVAC techs. Find more info about me and HVAC Training 101.