What Size Air Conditioner Do I Need For 200 Square Feet?

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Generally, you need a 6,000 BTU air conditioner for a 200 square-foot room. A few experts recommend slightly less, perhaps 5,000 BTUs. However, for optimal comfort, we believe you should purchase a 6,000 BTU unit.

The most important thing you need to understand is that this is a round-off figure. Different applications have different air conditioning needs. Even two similar-size rooms sometimes require different air conditioner capacities.

If you want to find the most accurate AC for your 200 square-foot room, the only solution is to do the calculation manually.

Two Ways to Calculate Your BTU Requirements

You can either use online calculators or the manual approach to calculate the amount of BTUs required for your application.

Using Online Calculators

Online BTU calculators are special software programs designed to help homeowners quickly determine how many British Thermal Units (BTUs) need an air conditioning project. A key benefit of online calculators is that your job is half done. All that’s required of you is to input figures, and the calculator will perform the calculations in the background and display a result on the screen.

Two critical inputs required from you are the size of the application (200 square feet) and your location.

Typically, larger rooms require more air conditioning BTUs. The calculator program may also ask for the location of the room within the house. That’s because rooms on upper floors typically require more air conditioning. The top-most floor particularly can be scorching hot given the proximity to the ceiling. However, if you have an attic fan installed, you may not need air conditioning as the fans help exhaust heat.

The purpose of the room may also come into play. Why? Because some rooms are inherently warmer given their use. For instance, the kitchen tends to be hotter because of all the cooking. Congested rooms, such as the garage, may also feel hotter. Meanwhile, bedrooms are generally cooler even in the hottest months because they have more space for air circulation.

Finally, your geographic location matters a lot. Houses in temperate climates are generally hotter, requiring more cooling effort than those in the cooler northern climates. For instance, on a scorching hot day in July, temperatures in the south can reach 100˚F. However, the hottest days rarely exceed 70˚F in the north.

You’ll need to come prepared with the above information if you intend to use an online calculator to determine the most appropriate AC size for your room.

Through Manual Calculation

An even better way to determine what size air conditioner you need for a 200 square-foot area is to do the math personally – without BTU calculators. Proceed as follows;

Determine the area of the room

Are you sure that the room is 200 square feet? If not, then begin by reaching for your tape measure to calculate the area afresh. Most rooms are either square or rectangular, so it should be easy to determine the area. Measure the length and width and multiply the two to determine the area of the room.

Multiply the area by 20

Experts recommend adding 20 BTUs per square foot for optimal air conditioning. Therefore, you can easily determine how many BTUs you need for a given application by multiplying the area (in square feet) by 20. For 200 square feet, it comes to 4,000 BTU. That’s the amount of BTUs you need for a 200 square-foot area.

Adjust for ceiling height

Go back and measure the height of your ceiling, i.e., the distance from the floor to the ceiling. The 20 BTUs per square foot recommendation is meant for standard ceiling heights, i.e., 8.0 feet. Is your ceiling height 8.0 feet? If not, adjust you need to adjust the final BTU value by 20% for every foot. Reduce it by 10% per foot for shorter ceilings and increase by 10% per foot for higher ceilings.

Adjust for occupancy 

You only need 4,000 BTUs per square foot if the room hosts a single occupant most of the time. However, if it will host more people, add 600 BTUs for every extra person. For instance, if it’s a bedroom for two kids, you need to add 600 BTUs. If it’s an entertainment center for four people, you need to add 600 BTUs for each of the three extra occupants, i.e., 1,800 BTUs in total. So, you’ll need at least 5,800 BTUs.

Adjust for sunlight exposure 

Some rooms are directly exposed to sunlight. As a result, these rooms become even hotter in the summer. Meanwhile, rooms in heavily shaded areas may remain relatively cool even in sweltering hot seasons. For this reason, you want to add 10% to the BTU value for sunlight-exposed areas and deduct 10% from the BTU figure for heavily shaded areas. 

Is it a kitchen?

Since kitchens can get pretty hot, you’re advised to add 4,000 BTUs to the final AC capacity. So, if you’ve determined that you need a 4,000 BTU AC, add 4,000 BTUs to make it 8,000 BTUs.

Other Key Considerations

Ceiling height, occupancy, exposure to sunlight, and application type, i.e., room use, are usually the first four factors you want to consider when trying to find the right AC size for your application. However, they aren’t the only factors. The following are also important;

  • Type of AC

Air conditioners come in five main categories – central air systems, ductless mini-split systems, window AC units, through-the-wall units, and portable air conditioners. First off, you don’t need a central air system for a 200 square-foot area. So that leaves you with the latter four. Of these four, ductless mini-split systems and window air conditioners are the best options, unless you want a portable AC.

  • Air Conditioner Efficiency 

The efficiency rating of an air conditioner directly affects the amount of cool air you’ll get in the room. So, for example, if you have two 8,000 BTU air conditioners, one rated 16 SEER and the other 25 SEER, the 25 SEER unit will bring more cool air into the room, assuming an equal electricity supply. That’s because lower-efficiency air conditioners produce less cool air for every watt of electricity consumed.

  • Heat pump option 

Some air conditioners are designed with built-in heat pumps that provide supplementary heating during winter. The heat pump component is important because it can be confusing when assessing AC BTU sizes. Though most heat pumps have the same rating for heating and cooling modes, others have varied ratings for the two functions. For example, the heat pump may be rated 8,000 BTU when the AC is 6,000 BTUs or vice versa. Don’t be confused.

  • Multi-zone mini split options 

Multi-zone mini-split systems are designed to serve at least two rooms, with some serving up to eight rooms at a go. But the BTU ratings can be confusing because the indoor air handlers often have different ratings from the outdoor compressor unit and even among themselves. Remember to focus only on the air handler. Therefore, for a 200 square room, you want to pick an air handler rated around 6,000 BTUs, even if the outdoor compressor is larger.

Tips to Get More from Your AC

Air conditioners can be costly to run. Even a small, 6,000 BTU air conditioner can cost over $70 to run per month during the cooling season. The following energy-saving tips can help reduce your power bill;

  • Set your thermostat high: For air conditioners, the lower you go, the higher your energy bills. Ideally, you want to set the thermostat around 78˚F. But feel free to go higher if you can. Even 80˚F is still cool enough.
  • Keep the sun out: We’ve mentioned sunlight exposure as a factor when determining the right AC size. If you can keep the sun out, you can reduce your energy consumption even further. Keeping the doors and windows closed would be an excellent first step.
  • Invest in insulation: A poorly insulated room quickly leaks the cool air while providing entry points for the hot air from outside. Proper insulation can help resolve the problem. If possible, invite an HVAC professional at the onset of the cooling season to assess your insulation quality and offer advice.
  • Keep the air filters clean: Most people don’t think about it, but dirty filters can also impact AC energy consumption. Why? Because dirty filters restrict airflow. They force the AC to work harder and run longer. Clean your AC filters at least once every 30 days to prevent this problem.
  • Use ceiling and attic fans: Fans help circulate air throughout the house, which means the AC no longer needs to pump cool air throughout the house. Moreover, fans can be set to remove stale air outside the house allowing. The standard fan also creates a breeze that leaves occupants feeling cooler, effectively reducing the need for air conditioning.


Generally speaking, you need a 6,000 BTU air conditioner for a 200 square-foot area. However, the actual figure can be lower or higher depending on your geographic location, the number of people who regularly use the room, and sunlight exposure, among other factors.

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