Sizing guide
Mini split sizing calculator
Mini splits are sized in BTUs per hour. Undersize and it runs flat-out on hot days; oversize and it short-cycles. Use the calculator, then sanity-check against the chart below — or let our experts confirm it free.
Recommended size
12,000BTU
Shop 12,000 BTU systemsMultiple rooms? Use the system builder
Estimates assume typical construction and climate. Not a substitute for a Manual J load calculation — our team verifies sizing on request, free.
Quick reference chart
| Room size | Recommended capacity |
|---|---|
| Up to ~250 sq ft | 6,000–9,000 BTU |
| 250–400 sq ft | 9,000 BTU |
| 400–550 sq ft | 12,000 BTU |
| 550–800 sq ft | 18,000 BTU |
| 800–1,100 sq ft | 24,000 BTU |
| 1,100–1,500 sq ft | 36,000 BTU |
| 1,500+ sq ft / open plan | 48,000 BTU |
How sizing works
The base rule is 20–30 BTU per square foot of living space. From there, real rooms adjust the number:
- Ceilings over 8 ft add ~10% per extra foot of height.
- Strong sun adds ~10%; heavy shade subtracts ~10%.
- Kitchens add ~4,000 BTU for appliance heat.
- Poor insulation (garages, sunrooms, older homes) adds 10–20%.
- Cold-climate heating as the primary heat source? Size for the heating load — ask us about Hyper Heat models.