Mini-Split for Bonus Rooms & Garages: What Size Do You Need?

If your bonus room or garage feels like an oven in summer and an icebox in winter, a mini-split system may be the perfect comfort solution. These versatile systems provide targeted air conditioning and heating without the need for extensive ductwork. For homeowners exploring ductless mini split installation in Fort Worth, choosing the right size is critical to getting efficient, consistent comfort year-round.

Why Mini-Splits Are Perfect for Hard-to-Condition Spaces

Bonus rooms and garages are notorious for temperature fluctuations because they’re often separate from the home’s main HVAC system. A ductless mini-split solves this by offering precise, zone-based control. Unlike window units or space heaters, mini-splits are quiet, energy-efficient, and designed to handle both cooling and heating with ease.

The right-sized unit ensures your space reaches the desired temperature quickly and maintains it efficiently. If the unit is too small, it will struggle to keep up. Too large, and it will short-cycle—wasting energy and wearing out faster.

How to Determine the Right Size Mini-Split

Sizing depends on your room’s square footage, insulation, ceiling height, and sun exposure. While a professional load calculation provides the most accurate answer, here’s a general idea of BTU ranges:

• 9,000 BTU: Up to 400 sq. ft. (small garage or bonus room)
• 12,000 BTU: 400–550 sq. ft. (average bonus room or two-car garage)
• 18,000 BTU: 600–1,000 sq. ft. (large converted spaces or workshops)

Other factors that influence sizing include:

• Ceiling height (taller rooms require more capacity)
• Insulation quality (poor insulation demands a stronger system)
• Window size and orientation (south-facing rooms may need extra cooling)

When in doubt, consult Fort Worth’s air conditioning pros to avoid under- or oversizing your system.

Multi-Zone vs. Single-Zone Mini-Splits

If your bonus room or garage is the only area you need to heat or cool, a single-zone system is usually sufficient. However, if you plan to condition multiple spaces—like a garage, office, and upstairs game room—a multi-zone system might be the better investment. It connects several indoor units to one outdoor condenser, allowing independent temperature control in each area. 

Homeowners often weigh the cost to install a mini split in DFW when comparing single- and multi-zone systems. While multi-zone units cost more upfront, they can be more economical in the long term if you’re upgrading comfort throughout your home.

Professional HVAC Services You Can Trust  

At Texas Air Doctors, we specialize in air conditioning, heating, and comprehensive HVAC services designed for Fort Worth’s unique climate. Whether you’re retrofitting a garage, finishing a bonus room, or upgrading your home’s comfort, our experts can help you choose the right mini-split size and handle the installation from start to finish.

Ready to transform your space? Contact Texas Air Doctors today to schedule your ductless mini split installation in Fort Worth and experience the comfort and efficiency you’ve been missing.