Write an article based on this "Measure the area you need the air conditioner to cool. Find an A/C unit with the recommended BTU rating for your space. Get an A/C unit with a higher BTU rating if your space receives a lot of sunlight."
Use a tape measure to measure the width and length of the indoor space you want to cool. Then multiply the width by the length. Different air conditioners have different cooling capacities, so you’ll need this information to select one that has the correct cooling capacity for the size of the space you want to cool. If there’s no wall or door separating the space you want to cool from an adjoining room, add the area of the adjoining room to your calculation because the air conditioner will have to cool that space as well. The cooling capacities of all air conditioners are measured in BTUs (British thermal units) per hour. By looking at a unit’s BTUs, you can know the area it is capable of adequately cooling. The higher a unit’s BTU, the larger the area it can cool. The label or online description of a specific air conditioner will typically state what area the unit is capable of cooling.  An air conditioner with a cooling capacity of 5,000 BTUs, for example, can cool rooms that are between 100–150 square feet (9.3–13.9 m2) in area. You’ll need an air conditioner with a cooling capacity of 6,000 BTUs to cool a room that’s 150–250 square feet (14–23 m2) in area. For a comprehensive guide to what BTU rating most closely matches the size of your room, visit https://www.energystar.gov/products/heating_cooling/air_conditioning_room?qt-consumers_product_tab=3#qt-consumers_product_tab. Aside from the size of the space you want to cool, the amount of sunlight it receives and other factors will also determine the BTU rating you’ll want to choose. Go with a unit with 10 percent higher capacity if your room receives a lot of direct sunlight.  Buy a unit with 10 percent less capacity if the room you’ll be cooling is heavily shaded. Add another 4,000 BTU if you’ll be using the air conditioner to cool your kitchen. If more than 2 people will be regularly spending time in the room, increase the capacity of the air conditioner you buy by 600 BTUs per person.