Mini Split Sizing

What size mini split do you need?

Pick your space — we’ll match the BTU. As a rule, a mini split needs about 20 BTU per square foot.

What are you cooling?

Room size 600 sq ft
1003,000 sq ft
Fine-tune for ceilings, sun & kitchen
18,000BTU 1.5 ton Best fit for a ~600 sq ft living room Covers up to 1,000 sq ft Shop 18K BTU →
Mini split size guide

6,000 BTU mini split · Up to 250 sq ft

A 6,000 BTU mini split is a 0.5-ton system for small rooms up to about 250 sq ft — a bedroom, home office, nursery, or compact den. It's the most efficient choice when you only need to cool or heat one small space without oversizing.

Shop 6K BTU mini splits →
See the full mini split size chart
Recommended mini split BTU by room square footage
Room sizeBTUTonTypical use
Up to 250 sq ft 6,000 0.5 Small bedroom, office
250–400 sq ft 9,000 0.75 Master bedroom, hotel room
400–550 sq ft 12,000 1 Studio, large bedroom, den
550–1,000 sq ft 18,000 1.5 Open living room, small apartment
1,000–1,200 sq ft 19,000 1.58 Large room or 2-zone system
1,200–1,500 sq ft 24,000 2 Large living space, garage
1,500–1,600 sq ft 28,000 2.33 Large space or multi-zone
1,600–1,700 sq ft 30,000 2.5 Great room, open floor plan
1,700–1,800 sq ft 36,000 3 Large open floor, small retail
1,800–2,100 sq ft 42,000 3.5 Multi-zone / light commercial
2,100–2,400 sq ft 48,000 4 Showroom, gym, commercial
2,400–2,700 sq ft 55,000 4.58 Large multi-zone / commercial
2,700–3,000 sq ft 60,000 5 Warehouse, open office

Based on the ~20 BTU/sq ft guideline (U.S. Dept. of Energy / ENERGY STAR). For odd layouts, an ACCA Manual J calculation is recommended.

Sizing CalculatorWhat Size Mini Split Do You Need?

Choosing the correct capacity is the most critical step in buying a ductless system. Our comprehensive mini split sizing guide removes the guesswork. As a general industry rule, a mini split requires about 20 BTU per square foot of living space. Whether you are wondering what size mini split do I need for a 300 sq ft bedroom or a massive 2,000 sq ft commercial layout, our accurate ductless ac sizing chart will help you find the exact match. Avoid the pitfalls of short-cycling and energy waste by matching your square footage to the perfect BTU output today.

Listen to Guide
🧮 20 BTU per Sq. Ft. Rule

Mini Split Sizing Guide & Chart

Selecting the exact capacity for your ductless system guarantees comfort, prevents humidity buildup, and maximizes your energy savings. If you are asking what size mini split do I need, the fundamental rule is 20 BTU per square foot. Review our comprehensive mini split square footage chart below to map your room dimensions to the precise HVAC tonnage required.

  • 📏 Accurate Square Footage
  • ⚖️ BTU to Ton Conversions
  • ☀️ Sun & Insulation Factors

Crucial Modifiers: Fine-Tuning Your BTU

The chart above provides your baseline. However, your specific environment requires you to adjust the capacity up or down based on these four crucial real-world variables:

  • Sunlight Exposure
    If the room is heavily shaded all day, reduce capacity by 10%. If the room has massive windows facing direct afternoon sun, increase capacity by 10% to 20%.
  • Kitchen Heat
    Kitchens generate massive amounts of ambient heat from ovens and stoves. If the mini split is installed in or adjacent to a kitchen, add 4,000 BTU to your baseline.
  • High Ceilings
    Calculations assume an 8-foot ceiling. If your room features vaulted or 10+ foot ceilings, you are cooling a larger volume of air. Increase your BTU size by at least 20%.
  • Poor Insulation (Garages)
    Uninsulated spaces like garages, sheds, or sunrooms suffer from extreme temperature bleed. Always size up by at least 30% to 50% compared to interior rooms.

FAQ: Mini Split Sizing & Capacity

🧮 How many BTUs do I need per square foot? ›
The standard HVAC rule of thumb is 20 BTUs per square foot for a room with standard 8-foot ceilings and average insulation. For example, a 500 square foot room multiplied by 20 equals 10,000 BTU, which means you should purchase a 12,000 BTU (1-Ton) unit.
⚠️ What happens if I buy a mini split that is too large? ›
Oversizing a mini split leads to a problem called "short-cycling." The oversized compressor will cool the air in the room so rapidly that it reaches the target temperature and shuts off before it has a chance to run air across the coils long enough to extract humidity. This leaves your room feeling cold but uncomfortably clammy and damp.
⚖️ What is the difference between BTUs and Tons? ›
They measure the exact same thing (cooling/heating capacity). 1 Ton is equal to 12,000 BTU/hr. So, an 18,000 BTU unit is 1.5 Tons, and a 24,000 BTU unit is 2 Tons. "Tonnage" is simply an older HVAC shorthand terminology.
🔄 How do I size a Multi-Zone system? ›
First, calculate the individual BTU requirement for each room receiving an indoor unit. Then, add those numbers together. The outdoor condenser you select must have a maximum capacity equal to or slightly larger than the total required BTU of the indoor units combined.