What Size Mini Split Do I Need?

A mini-split HVAC system, also known as a ductless system, is an energy-efficient way to heat and cool individual rooms or spaces. Unlike central air systems, mini-splits allow for precise temperature control, making them a popular choice for homeowners looking to improve comfort and efficiency.

How to Determine the Right Mini-Split Size

Mini-split systems are measured in British Thermal Units (BTUs), which indicate the system’s cooling or heating capacity. The correct BTU rating depends on various factors, including room size, insulation quality, climate, and window placement. The first thing you should do is use our mini split calculator!

1. Room Size & Layout 

A general rule of thumb is to allocate 20 BTUs per square foot.

For example:

• A 500 sq. ft. room requires approximately 10,000 BTUs.

However, other factors—such as ceiling height, room shape, and number of walls exposed to the outdoors—can impact this calculation.

2. Insulation & Sunlight Exposure 

• Well-insulated homes retain heat in winter and keep cool air in during summer, allowing for smaller BTU requirements.
• Poor insulation means more heat loss in winter and excessive heat gain in summer, requiring a larger mini-split system.
• Rooms with direct sunlight need extra cooling capacity, while shady rooms require less cooling power.

3. Climate Considerations 

Your local climate plays a crucial role in mini-split sizing:

• Hot climates: Require a larger unit for increased cooling capacity.
• Cold climates: Need stronger heating capacity, especially in areas where temperatures drop below freezing.
• Moderate climates: Can use a standard-sized unit without extra adjustments.

4. Number of Windows 

• More windows = More heat loss/gain → Requires a larger unit.
• Few or small windows → Allows for a smaller system.
• South-facing windows bring in more sunlight, requiring a stronger cooling capacity.

Mini-Split BTU Sizing Chart

Mini-Split Size Recommendations

Small Rooms (100-300 sq. ft.)

🏡 Ideal for: Bedrooms, offices, small studies.
Recommended BTU range: 5,000 – 7,000 BTUs.

Medium Rooms (400-700 sq. ft.)

🏡 Ideal for: Living rooms, kitchens, larger bedrooms.
Recommended BTU range: 8,000 – 14,000 BTUs.

Large Open Spaces (800-1,000+ sq. ft.)

🏡 Ideal for: Open-concept living areas, basements.
Recommended BTU range: 16,000 – 20,000+ BTUs.

Mini-Split BTU Sizing for Large Spaces

Mini-Split Sizing Tips ✅

1. Get a Professional Sizing Assessment 

HVAC professionals can accurately calculate your mini-split’s BTU needs based on insulation, ceiling height, and climate.

2. Don’t Oversize or Undersize 

⚠️ Oversized units cycle on/off too often, leading to inefficient energy use and excess humidity.
⚠️ Undersized units run constantly, raising energy costs and struggling to keep the room comfortable.

3. Proper Placement Matters 

✅ Mount indoor units high on a wall for better airflow.
✅ Keep the outdoor unit clear of obstructions for optimal efficiency.
✅ Avoid direct sunlight or drafts affecting the thermostat’s readings.

Need Help Choosing the Right Mini-Split?

At The Trade Table, we specialize in top-quality mini-split systems designed for maximum efficiency and comfort. Whether you're cooling a single room or heating an entire home, we have the perfect system for your needs.

🔥 Shop Mini-Splits Today: The Trade Table