Before you even start shopping, measure your room's length and width to find its square footage. This number will guide your choice.

• Under 5,000 BTUs: Perfect for small, personal spaces like a home office or a small bedroom, typically up to 150 sq. ft.
• 5,000 to 8,000 BTUs: This is the sweet spot for most standard bedrooms and living rooms, covering areas from 150 to 350 sq. ft.
• 8,001 to 12,000 BTUs: Step up to this range for larger master bedrooms, big living rooms, or small open-plan areas, generally from 350 to 550 sq. ft.
• 12,001 to 18,000 BTUs: Ideal for cooling large, open-concept spaces or multiple connected rooms, covering up to 1,000 sq. ft.
• Over 18,000 BTUs: This is heavy-duty cooling power, best suited for very large open areas, workshops, or even entire floors of a smaller home.

Always start by calculating your square footage. If the room is very sunny or has high ceilings, consider choosing a unit at the higher end of the recommended BTU range.

Don't just guess—grab a tape measure. You need to know your window's width and the height of its opening before you click "buy."

• Window Width: This refers to the width of your window's opening. Most AC units are designed for standard double-hung windows and come with accordion side panels to fill gaps. Common ranges are Under 20 Inches, 20 to 26 Inches, and 27 to 36 Inches.
• Minimum Window Height: This is the vertical space needed to slide the unit into the window. Ensure your window can open tall enough to accommodate the unit's height.
• Installation Kit Included: A good unit will come with everything you need: side panels, insulation foam, screws, and sometimes a support bracket. This ensures a secure and well-sealed installation without an extra trip to the hardware store.

Measure twice, buy once. Verifying your window dimensions and ensuring a complete installation kit is included will make the setup process smooth and effective.

Consider how you want to manage your comfort. Smart features are no longer a gimmick and provide real-world benefits, especially for those on the go.

• Remote: The standard for most modern units. A basic infrared remote lets you adjust temperature, fan speed, and modes from anywhere in the room.
• Wifi & Mobile App: A WiFi-enabled AC connects to your home network, allowing you to control it via a Mobile App on your smartphone. You can turn it on before you get home, set schedules, and monitor energy usage from anywhere.
• Voice Control: The ultimate hands-free convenience. Units with this feature can sync with smart home assistants like Amazon Alexa or Google Assistant, allowing you to change settings with a simple voice command.

While a remote is essential, WiFi and app control provide a major upgrade in convenience and energy management. It allows you to run the AC only when you need it, saving money without sacrificing comfort.

A cheaper, inefficient unit can cost you more in the long run through higher electricity bills. Investing in efficiency pays off every month.

• Efficiency: Look for the ENERGY STAR label. A unit that Meets Energy Star standards is certified by the EPA to be more energy-efficient than models that are Not Certified. Models that Exceeds Energy Star are the best of the best, offering maximum savings.
• Refrigerant: The chemical that cools the air matters. Avoid old units with R-22, which is harmful to the ozone layer. The longtime standard was R-410a. The new, better option is R-32, which is more efficient and has a much lower global warming potential. Other eco-friendly options like R-290 are also excellent.

At a minimum, choose an Energy Star certified model. For the refrigerant, look for units using R-32, as it represents the modern standard for efficiency and environmental responsibility.