
To size a swamp cooler for your home, you'll need to consider the square footage of the space you want to cool. This will determine the size of the cooler you'll need.
A general rule of thumb is to use 20-30 BTUs per square foot of living space. For example, if your home is 1,000 square feet, you'll need a cooler that can handle 20,000-30,000 BTUs.
To calculate the total BTUs needed, multiply the square footage by the BTUs per square foot. In this case, 1,000 square feet x 25 BTUs per square foot equals 25,000 BTUs.
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Understanding Swamp Cooler Capacity
Swamp cooler capacity is crucial to determine the right size for your cooling needs.
Air flow is one of the three main considerations for swamp cooler sizing, along with the cooling capacity of the evaporation and cabinet size. This includes blade size and tank size.
To estimate the necessary tank size, consider the water tank's capacity, which will define how long a cooler can work before needing a refill. For example, the Evapolar models work up to 9 hours on one tank refill.
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The cooling capacity of a swamp cooler is measured in BTUs, but it's essential to use it as an estimate, not an exact number. You can use the chart to get a general starting point for swamp cooler sizing, but keep in mind that these numbers will vary by manufacturer and the actual conditions of your area.
Here's a chart to help you estimate the cooling capacity needed for different areas:
Calculating Cooling Needs
Calculating cooling needs is a crucial step in sizing a swamp cooler. The usual formula to calculate the swamp cooler size is by multiplying the square feet needed to be cooled by the ceiling height in feet, then dividing by two.
To get an estimate of the cooling capacity needed, you can use the airflow and BTUs method. Air flow is a key consideration, as it affects how well the cooler can circulate air and remove heat from the space. The chart below shows the suggested BTUs per hour for different area sizes.
Manufacturers often use a shorthand to refer to the sizes of their units, with a 12,000 BTU unit being called a "1-ton" unit, and a 24,000 BTU unit being called a "2-ton" unit.
Calculations
Calculations are a crucial part of determining your cooling needs. To calculate the CFM (cubic feet per minute) of the cooler you need, divide the square footage of the area you want to cool by two. This will provide you with the total CFM required.
The size of the area to be cooled is a key factor in determining the CFM needed. For example, if you're cooling a 100-150 square foot area, you'll need a cooler with a CFM of around 5,000.
The chart below shows the recommended CFM and BTU ratings for different area sizes:
Keep in mind that these are general estimates and the actual CFM and BTU requirements may vary depending on the specific conditions of your area.
The usual formula to calculate the swamp cooler size is square feet needed to be cooled multiplied by ceiling height (in feet), divided by two. This will give you the desired CFM.
Here's an interesting read: Swamp Cooler Cfm
Humidity
Humidity plays a crucial role in determining the efficiency of your cooling device. Swamp coolers work best in dry climates because they use evaporation for cooling.
Humidity levels in the room you need to cool will define the final efficiency of your device. The more humid the environment, the less effective your cooling solution will be.
Dry climates are ideal for swamp coolers, which can struggle in humid environments where the air is already saturated with moisture.
Consider reading: Swamp Coolers in Humid Climates
Choosing the Right Size
Choosing the right size swamp cooler is crucial to its effectiveness. You'll need to consider the area you want to cool and the airflow it can handle.
Look at the cooler's CFM (Cubic Feet per Minute) or CMM (Cubic Meters per Minute) rating to gauge its airflow. This number measures the amount of air a swamp cooler can move per minute.
Use half the airflow for the area you want to cool as a starting point. For example, if you're cooling a 10' x 10' x 10' tent, you'll need a cooler with at least 500 CFM.
The more enclosed an area is, the less airflow you'll need. However, if the area is more open, you'll need additional airflow to compensate.
A unit with more airflow won't increase the evaporative cooling effect, but it will increase the amount of breeze you'll feel.
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The Space

To determine the right size of your evaporative cooler, you need to consider the size of the space you need to cool. The height of the ceiling is also a crucial factor, as specific formulas apply to the sizing of evaporative coolers.
The size of the space can vary greatly, but it's essential to know the exact dimensions to pick the correct swamp cooler size. This will ensure that your cooler can effectively cool the area without wasting energy or resources.
If you have a large space to cool, you'll need a larger swamp cooler. These units have fan blades that can start at 16 inches in diameter and go up to 48 inches or more. They're designed to move thousands of cubic feet per minute, making them perfect for cooling large areas.
The cabinet size of larger swamp coolers can be substantial, with some units requiring a space of over 3 feet square and deep. However, they're still energy-efficient, using very little electricity – often less than 10 amps at 115 volts.
If this caught your attention, see: Are Swamp Coolers Energy Efficient
Choosing the Right One

Choosing the right size evaporative cooler is crucial to ensure it meets your cooling needs. The cooling power of a portable evaporative cooler is measured in CFMs (cubic feet per minute).
You need to consider the square footage of the space you want to cool and its ceiling height to determine the required CFM. For example, if you're trying to cool a 500 square foot room with 10-foot ceilings, you'll need a cooler with at least 2,500 CFM.
A good rule of thumb is to use half the airflow for the area you want to cool as a starting point. This is because swamp coolers have the additional cooling power of evaporation. For instance, if you're holding an outdoor event in a tent that's 10′ wide x10′ long x10′ high (1,000 cubic feet), you'll need a cooler with at least 500 CFM.
More open areas require more airflow, but the basic formula can be used as a starting point. A unit with more airflow won't increase the evaporative cooling effect, but it will increase the amount of breeze you'll feel, which can be up to 8º cooler than still air.
Here's an interesting read: Swamp Cooler Dew Point

Consider the humidity level in the room, as evaporative coolers work best in drier climates. The efficiency of the device will be determined by the humidity level, so choose a cooler that suits your climate.
Smaller swamp coolers, best used for "spot cooling" or "small area cooling", use fan blades smaller than 16 inches / 40 cm and have cabinets that are sleeker than larger-sized units. They range from as little as 250 CFM all the way up to 3,800 CFM.
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Cabinet
A well-chosen cabinet can make all the difference in a room's functionality and style.
Standard cabinet sizes are typically 24, 30, or 36 inches wide, making it easy to find a size that fits your space.
If you're looking for a more unique look, consider a custom cabinet that can be tailored to your specific needs.
The depth of a cabinet is also an important consideration, as it can affect the overall look and feel of your room.
Considering Your Options
So you're trying to size a swamp cooler, huh? First, you need to consider the square footage of the area you want to cool. A general rule of thumb is to calculate the square footage by multiplying the length and width of the space.
The amount of cooling needed also depends on the climate and location of your home. If you live in a hot and dry area, you'll need a larger swamp cooler to handle the heat. In areas with high humidity, a smaller cooler may be sufficient.
The type of roofing on your home can also impact the sizing of your swamp cooler. A darker-colored roof can absorb more heat, requiring a larger cooler to compensate. A lighter-colored roof, on the other hand, can stay cooler and may only need a smaller cooler.
Recommended read: Swamp Cooler Roof
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