Sliding windows, including sash, vertical, and casement styles, are fantastic for letting in natural light and fresh air. But when summer heat hits, they can be a real headache for traditional window air conditioner installations. Standard AC units are typically designed for double-hung windows, leaving you scrambling for a solution. Don’t sweat it! There are fantastic options out there, including specialized units and clever kits that make cooling your space with sliding windows a breeze.

Finding the best window air conditioner for sliding windows means looking for units designed specifically for these window types or portable ACs that come with suitable window kits. We’ve done the digging to bring you our top 10 picks, ensuring you can enjoy a perfectly chilled home, no matter your window style.

Let’s dive into the options and help you beat the heat!

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Our Top Picks for the Best Window Air Conditioner for Sliding Windows

1. Midea 8,000 BTU Smart Inverter Air Conditioner Window Unit

This Midea unit isn’t just an air conditioner; it’s a multi-season comfort system designed to keep your home comfortable year-round. Boasting an impressive 8,000 BTUs, it’s perfect for larger rooms up to 350 sq. ft. What really makes it stand out is its smart inverter technology, which not only provides powerful cooling but also significant energy savings. Plus, it doubles as a heater for those cooler days, making it a truly versatile choice.

• Key Features:

  • 8,000 BTU cooling and supplemental heating (works >41°F outside)
  • SmartHome App, Alexa, and Google Assistant voice control
  • Energy Star certified with variable-speed inverter technology (up to 35% energy savings)
  • Ultra-low noise performance (as low as 45 dBA)
  • 5 Modes (Heat, Auto, Cool, Dry, Fan), 3 speeds, 24-hr Timer, ECO mode
  • Fits double-hung windows 24″ to 38.5″ wide (14.5″ vertical opening)

• Pros:

  • Excellent energy efficiency with inverter technology
  • Quiet operation, great for bedrooms or offices
  • Smart features for convenient control
  • Year-round usability with heating function
  • Easy-to-clean washable filter

• Cons:

  • Heating function is limited to temperatures above 41°F
  • Installation requires a specific window opening type

• User Impressions: Users rave about its whisper-quiet operation and the significant savings on their energy bills thanks to the inverter technology. The smart controls are a huge hit, allowing them to adjust settings from anywhere, while the heating function adds unexpected value for shoulder seasons.
  See it on Amazon here

2. Keystone 8,000 BTU Slider Window Air Conditioner and Dehumidifier

Specifically engineered for your non-traditional windows, this Keystone 8,000 BTU unit is a dream come true for homes with sliding or casement windows. It offers robust cooling for rooms up to 350 sq. ft. and includes a built-in dehumidifier to tackle muggy conditions. Its design focus on accommodating slider windows makes installation much smoother than trying to adapt a standard unit.

• Key Features:

  • 8,000 BTU cooling capacity for up to 350 sq. ft.
  • Designed to fit standard sliding and casement windows
  • 3 cooling modes, 3 fan speeds, 4-way adjustable air louvers
  • Built-in dehumidification system (removes 0.9 liters/hour)
  • Programmable timer, ‘Energy Saver’ and ‘Sleep’ modes
  • Removable chassis for window or through-wall installation
  • Minimum window height: 21.3″; width: 15.5″ to 16.3″

• Pros:

  • Ideal fit for sliding and casement windows
  • Effective dehumidification in addition to cooling
  • Energy-saving modes to reduce electricity costs
  • Flexible installation options
  • Directable airflow for personalized comfort

• Cons:

  • May require specific window dimensions for a perfect fit
  • Lacks smart home integration found in newer models

• User Impressions: Customers love how easily this unit installs into their sliding windows, a common pain point for many. They appreciate its powerful cooling and the added benefit of dehumidification, making their rooms feel much more comfortable even on humid days. The energy-saver mode is frequently praised.
  See it on Amazon here

3. Midea 8,000 BTU U Shaped Smart Inverter Window Air Conditioner

The Midea U-Shaped AC isn’t just a gimmick; its unique design allows your window to close almost completely, effectively blocking outdoor noise and improving security. This 8,000 BTU unit is incredibly quiet, running as low as 32 dBA, making it 10x quieter than many traditional units. Coupled with its smart inverter technology, it’s an Energy Star certified powerhouse that offers fantastic cooling and energy savings for rooms up to 350 sq. ft.

• Key Features:

  • Unique U-shape design allows window to block noise and open for fresh air
  • Ultra-low noise performance (as low as 32 dBA)
  • Over 37% energy savings with advanced DC Inverter technology (Energy Star certified)
  • Wi-Fi enabled for SmartHome app control, Alexa, and Google Assistant
  • Anti-theft mechanism when window is closed
  • Robust, quick-snap bracket installation
  • Fits single or double-hung windows with width 22″-36″, min. height 13.75″

• Pros:

  • Exceptional quietness, ideal for bedrooms
  • Significant energy efficiency and cost savings
  • Smart control options for ultimate convenience
  • Allows window opening for natural light/air when AC is off
  • Enhanced security with window lock feature

• Cons:

  • Installation is specific to double-hung windows, not casement or true sliders (though the window closes over it)
  • Higher initial cost due to advanced technology

• User Impressions: This unit receives overwhelming praise for its unbelievably quiet operation, transforming noisy window AC experiences. Users are thrilled with the energy savings and the convenience of smart controls. The ability to close the window almost completely and still enjoy natural light or air is a game-changer for many.
  See it on Amazon here

4. Soleus Air Sliding Window Kit, Reinforced Aluminum

While not an air conditioner itself, this Soleus Air Sliding Window Kit is a crucial accessory for anyone with a Soleus Air Exclusive Hybrid “Saddle” Air Conditioner looking to install it in a horizontal sliding window. It’s designed for seamless integration, offering a high-quality, adjustable solution that maintains your view and energy efficiency. If you have the compatible AC unit, this kit is what you need for a tidy and effective setup.

• Key Features:

  • Adjustable to fit horizontal gliding windows (23.5″ to 43″ height)
  • Easy, tool-free installation (no drilling required)
  • High-quality plexiglass maintains outside view and natural light
  • Reinforced aluminum frame with included screws for secure locking
  • Energy-efficient foam insulation for a tight seal
  • Includes a window lock for added security

• Pros:

  • Specifically designed for compatible Soleus Air Hybrid ACs
  • Tool-free installation, very user-friendly
  • Preserves your window view and natural light
  • Excellent sealing for improved energy efficiency
  • Adds security with an included window lock

• Cons:

  • Only compatible with Soleus Air Exclusive Hybrid “Saddle” Air Conditioners
  • It’s a kit, not a standalone AC unit

• User Impressions: Owners of compatible Soleus Air ACs commend this kit for its perfect fit and ease of installation in sliding windows. They appreciate how it maintains the aesthetic appeal of their window while providing excellent insulation, preventing hot air from seeping in around the AC. The included lock is a welcome bonus for security.
  See it on Amazon here

5. Perfect Aire 10,000 BTU Slider Air Conditioner Window A/C

When you need serious cooling power for your sliding windows, the Perfect Aire 10,000 BTU Slider Air Conditioner steps up. This unit is built to cool larger spaces, ranging from 400-450 sq. ft., making it ideal for living rooms or open-plan areas with horizontal sliding or crank-out casement windows. Its ‘Follow Me’ remote ensures the temperature you set is the temperature you feel, wherever you are in the room.

• Key Features:

  • 10,000 BTU cooling capacity for 400-450 sq. ft.
  • Adjustable temperature settings (62°F – 86°F)
  • Expandable window mounting kit for horizontal sliding/casement windows
  • Fits window width 15½”/16¼” (min./max.) and height 21¼”/39½” (min./max.)
  • 3-speeds in cool and fan modes
  • Full function remote control with ‘Follow Me’ portable thermostat technology
  • Front-mounted, tilt-out air filter for easy cleaning

• Pros:

  • High cooling capacity for larger rooms
  • Designed specifically for sliding and casement windows
  • ‘Follow Me’ remote ensures precise temperature control
  • Easy-to-access and clean air filter
  • Flexible temperature and fan settings

• Cons:

  • May be noisier than inverter-based units
  • No smart home connectivity

• User Impressions: Users with larger rooms and sliding windows are very satisfied with this unit’s cooling power and its perfect fit. The ‘Follow Me’ remote is frequently highlighted as a favorite feature, providing accurate temperature readings right where they are. Installation is noted as straightforward for compatible windows.
  See it on Amazon here

6. Amazon Basics 5000-BTU Small Window Air Conditioner

For smaller spaces up to 150 sq. ft., like bedrooms or home offices, the Amazon Basics 5000-BTU Small Window Air Conditioner offers efficient and reliable cooling. While it’s a standard window unit, its compact size and included mounting kit make it adaptable for certain sliding window setups where a vertical kit or careful installation is planned. It’s a no-frills, effective option for personal comfort.

• Key Features:

  • 5000 BTU cooling capacity for rooms up to 150 sq. ft.
  • Two-in-one functionality: cooling and fan-only modes
  • Easy-access, washable filter for dust and allergen capture
  • 7 precise temperature settings, 2-speed cooling/fan modes
  • 2-way air direction control
  • Low noise level up to 56 dB
  • Fits standard windows 23″-36″ wide and minimum 13″ high (adaptable for vertical sliding)

• Pros:

  • Cost-effective solution for small rooms
  • Simple and straightforward operation
  • Easy to maintain with washable filter
  • Customizable comfort settings
  • Relatively quick installation for standard window sizes

• Cons:

  • Not specifically designed for sliding windows, may require extra sealing for a perfect fit
  • Basic features, no smart connectivity or advanced modes

• User Impressions: Customers appreciate the affordability and efficiency of this Amazon Basics unit for their small rooms. They find it provides ample cooling and is easy to operate. While not explicitly for sliding windows, those who’ve adapted it praise its compact size and cooling ability for its price point.
  See it on Amazon here

7. Portable Air Conditioner Window Kit (UNAOIWN)

If you’re already using a portable air conditioner or planning to get one, this UNAOIWN AC window vent kit is an essential accessory for securing the exhaust hose in vertical or horizontal sliding windows. It provides an adjustable, durable, and well-sealed solution to vent hot air out, ensuring your portable AC performs at its best. This kit is a versatile answer for many looking for the best window air conditioner for sliding windows if they choose a portable unit.

• Key Features:

  • Includes 4 plates, 5.9″ diameter duct coupler, filter, screw accessories (AC hose and unit not included)
  • Made of high-quality, anti-extrusion, anti-aging PVC
  • Suitable for most vertical and horizontal sliding windows
  • Adjustable length range: 17 inches or 27 inches to 65 inches (various plate combinations)
  • Excellent sealing performance with included 3.5M sealing strip
  • No tools required for easy installation

• Pros:

  • Highly versatile for both vertical and horizontal sliding windows
  • Durable PVC construction for multi-year use
  • Excellent sealing to prevent hot air intrusion and save energy
  • Easy, tool-free installation and disassembly
  • Compatible with most portable AC exhaust hoses (5.9″ diameter)

• Cons:

  • Does not include the AC unit or hose itself
  • Some manual adjustment and sealing strip application needed

• User Impressions: Users praise this kit for its adaptability to various sliding window sizes and its robust build quality. The included sealing strip is a huge plus, ensuring a tight seal that significantly improves their portable AC’s efficiency. They find it easy to install and a great value for extending their portable AC’s utility.
  See it on Amazon here

8. BLACK+DECKER Portable Air Conditioner, 10,000 BTU (6,300 SACC)

For those who prefer the flexibility of a portable unit that can be moved from room to room, the BLACK+DECKER 10,000 BTU Portable Air Conditioner is an excellent choice. It’s a three-in-one unit, offering cooling, dehumidifying, and fan functions for spaces up to 450 sq. ft. Its casters and side handles make mobility easy, and it comes with an installation kit suitable for various window types, including sliding ones.

• Key Features:

  • 10,000 BTU (6,300 BTU SACC) cooling capacity for rooms up to 450 sq. ft.
  • 3-in-1 unit: air conditioner, dehumidifier, and fan
  • Full function remote control with ‘FOLLOW ME’ portable thermostat
  • Top-mounted control panel with LED display
  • Easy mobility with casters and side handles
  • Includes an easy-to-install window kit (adaptable for sliding windows)

• Pros:

  • Versatile 3-in-1 functionality
  • Portable design for room-to-room cooling
  • ‘FOLLOW ME’ remote ensures accurate temperature
  • Good cooling capacity for medium to large rooms
  • Includes a basic window kit

• Cons:

  • Portable ACs are generally less energy-efficient than window units
  • Exhaust hose and window kit setup can be less aesthetically pleasing than dedicated window ACs

• User Impressions: Many users appreciate the convenience of being able to move this unit wherever cooling is needed most. The ‘FOLLOW ME’ remote is a consistent highlight for its ability to maintain comfort. While the window kit requires some effort for a sliding window, most find it manageable and effective.
  See it on Amazon here

9. BYOFI Portable Air Conditioner Window&Sliding Door Vent Kit

Another excellent option for portable AC users, the BYOFI Portable Air Conditioner Window & Sliding Door Vent Kit is highly adjustable and robust, designed to fit a wide range of vertical or horizontal sliding windows and even sliding doors. Its upgraded 4-in-1 coupler with a mesh filter is a thoughtful addition, preventing unwanted outdoor elements from entering your home.

• Key Features:

  • High-quality PVC construction, anti-aging and high-temperature resistant
  • Adjustable length range of 16.9″ – 90″ with 2-6 panels for versatility
  • Upgraded 4-in-1 coupler with mesh interface for 5.1″ or 5.9″ hoses (blocks pests/debris)
  • Value kit includes 6 panels, 5.9″ exhaust hose, coupler filter, rain cover, screws, manual, and sealing tape
  • Suitable for most vertical or horizontal sliding windows and sliding doors

• Pros:

  • Extremely wide adjustable range for various window/door sizes
  • Durable materials for long-term use
  • Innovative coupler with filter for improved air quality and pest control
  • Comprehensive kit with all necessary accessories, including sealing tape
  • Easy to install and disassemble

• Cons:

  • Installation can be fiddly to get a perfect seal without gaps
  • Hose is included, but it’s still a portable setup

• User Impressions: Users are impressed with the vast adjustability of this kit, making it compatible with even unusually sized sliding windows and doors. The mesh filter in the coupler is a standout feature for keeping bugs and debris out. The included sealing tape is often praised for helping achieve a tight, energy-efficient fit.
  See it on Amazon here

10. JEACENT Portable Air Conditioner Sliding Door AC Vent Kit

Rounding out our list, the JEACENT Portable Air Conditioner Sliding Door AC Vent Kit offers a patented, seamless design for effectively sealing your portable AC hose in sliding windows or doors. This kit focuses on a hassle-free installation and a 100% airtight seal, crucial for maximizing your portable AC’s efficiency and keeping your room cool for longer.

• Key Features:

  • Patented seamless design with exclusive bottom panel joint
  • Fits portable AC vent hoses with 5.1″ or 5.9″ external diameter
  • Max adjustable length of 90″ (universal for sliding doors or windows)
  • Easy installation: slot panels, slide to length, lock nuts
  • Sturdy and thicker PVC construction
  • Includes 6 panels, 6 lock-nuts, 1 universal adapter

• Pros:

  • Patented design for a truly seamless and airtight fit
  • Very wide adjustable range for various openings
  • Simple and quick installation process
  • Thicker PVC for enhanced durability and insulation
  • Effectively keeps hot air out, saving electricity

• Cons:

  • Does not include the portable AC hose or the unit itself
  • May not be suitable for very short window openings

• User Impressions: Customers love the JEACENT kit for its straightforward installation and how effectively it seals the window, preventing any hot air from sneaking back in. The sturdier PVC panels and the seamless design are frequently mentioned as improvements over other kits, leading to a more stable and energy-efficient setup.
  See it on Amazon here

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FAQ: Best Window Air Conditioner for Sliding Windows

Q1: Can I use a regular window air conditioner in a sliding window?
A: Generally, no. Regular window ACs are designed for double-hung windows, which open vertically, allowing the AC unit to sit horizontally. Sliding windows open horizontally, making it difficult to properly secure and seal a standard unit. You’ll need a specific sliding window AC unit or a portable AC with a suitable window kit.

Q2: What’s the main difference between a dedicated sliding window AC and a portable AC with a kit?
A: A dedicated sliding window AC (sometimes called a casement or sash AC) is a single unit designed to fit vertically into the sliding window opening. It’s usually more energy-efficient and quieter than a portable unit. A portable AC sits on the floor and uses a hose to vent hot air through a special window kit, offering more flexibility to move the unit but typically with less efficiency and higher noise levels.

Q3: How do I measure my sliding window for an air conditioner?
A: For a dedicated sliding window AC, you’ll need to measure the minimum and maximum vertical height of your window opening, as well as the width of the open sash. For a portable AC window kit, measure the vertical or horizontal length of the window opening where the kit will be installed to ensure the panels are adjustable to that range. Always check the product specifications carefully!

Q4: Are sliding window air conditioners energy efficient?
A: Many modern sliding window air conditioners, especially those with inverter technology (like some Midea U-shaped models), are very energy-efficient. They often carry an Energy Star rating, indicating they meet strict energy efficiency guidelines. Portable ACs, while convenient, are typically less energy-efficient than dedicated window units due to heat loss through the exhaust hose and less effective sealing.

Q5: What BTU size do I need for my room?
A: BTU (British Thermal Unit) determines the cooling capacity. Here’s a general guide:
– 150 sq. ft.: 5,000 BTU
– 250 sq. ft.: 6,000 BTU
– 300 sq. ft.: 7,000 BTU
– 350 sq. ft.: 8,000 BTU
– 400-450 sq. ft.: 10,000 BTU
Consider factors like high ceilings, direct sunlight, and heat-generating appliances, which might require slightly more BTUs.

Q6: How important is the dBA rating for an AC unit?
A: The dBA (decibels A-weighted) rating measures the noise level. A lower dBA means a quieter unit. This is extremely important if the AC is for a bedroom, office, or living area where noise can be disruptive. Units around 45-55 dBA are generally considered quiet, while inverter units can drop into the 30s dBA, which is whisper-quiet.

Q7: Do these units offer heating as well?
A: Yes, some advanced models, like the Midea 8,000 BTU Smart Inverter Air Conditioner Window Unit, offer both cooling and supplemental heating functions, making them multi-season appliances. This can be a great feature for transitional weather, but always check the operating temperature range for the heating function.