A 2-car garage (400–500 sq ft) typically needs an 18,000–24,000 BTU mini split for cooling and heating, costing $1,500–$4,000 installed depending on insulation level and brand choice. The best garage mini split is the MrCool DIY 4th Gen — its DIY installation saves $1,000–$2,500 in a space where premium noise levels and build quality matter less than in a bedroom or living room.
Garage BTU Sizing Guide
Garages have unique sizing challenges: they're often poorly insulated, have large door openings, contain heat-generating equipment, and experience massive temperature swings. Standard residential BTU calculations undersize for garages.
| Garage Type | Size (sq ft) | Insulated | Recommended BTU | Recommended Unit |
|---|---|---|---|---|
| 1-car | 200–300 | No | 12,000–15,000 | 12K or 15K |
| 1-car | 200–300 | Yes | 9,000–12,000 | 9K or 12K |
| 2-car | 400–500 | No | 18,000–24,000 | 18K or 24K |
| 2-car | 400–500 | Yes | 12,000–18,000 | 12K or 18K |
| 3-car | 600–800 | No | 24,000–36,000 | 24K or 36K |
| 3-car | 600–800 | Yes | 18,000–24,000 | 18K or 24K |
Worked Example: Uninsulated 2-Car Garage in Dallas, TX
- Garage: 450 sq ft, uninsulated walls, single-pane windows, 10-ft ceilings
- Base: 450 × 30 = 13,500 BTU
- Uninsulated: +30% → +4,050 BTU
- High ceilings: +25% → +3,375 BTU
- Hot climate: +15% → +2,025 BTU
- Adjusted: 22,950 BTU
- Recommended: 24,000 BTU unit
Worked Example: Insulated 1-Car Garage in Portland, OR
- Garage: 250 sq ft, insulated walls, 8-ft ceilings
- Base: 250 × 30 = 7,500 BTU
- Good insulation: no adjustment
- Mild climate: no adjustment
- Adjusted: 7,500 BTU
- Recommended: 9,000 BTU unit
Top Garage Mini Split Picks
| Rank | Model | BTU | SEER2 | Price | Why |
|---|---|---|---|---|---|
| 1 | MrCool DIY 4th Gen 18K | 18,000 | 20.0 | $1,300–$1,700 | Best value, DIY install |
| 2 | MrCool DIY 4th Gen 24K | 24,000 | 19.0 | $1,500–$2,000 | Large garages, DIY |
| 3 | Senville SENL-18CD | 18,000 | 18.0 | $800–$1,100 | Budget option |
| 4 | Senville SENL-24CD | 24,000 | 17.5 | $1,000–$1,400 | Budget large garage |
| 5 | Fujitsu RLS3 18K | 18,000 | 22.0 | $1,600–$2,000 | Premium, quiet |
Key Takeaways
Key Takeaway
- How to size and choose a mini split for your garage — BTU requirements by garage size, insulation factors, top picks, and installation tips
- Always verify specifications against the AHRI directory for independently certified performance data
- Consider the federal $2,000 tax credit and state rebates when calculating total cost