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Mini Split Calculator · Free Tool

Mini Split
Size Calculator

Find the right BTU ductless mini split for your room. Single-zone and multi-zone sizing with climate, insulation, and sun exposure factors.

How to Size a Ductless Mini Split

Mini splits come in standard sizes: 9K, 12K, 18K, 24K, 36K, and 48K BTU. The right size depends on room area, climate, insulation, and sun exposure. As a starting point, most rooms need 20-30 BTU per square foot.

Single Zone vs Multi-Zone

Single-zone serves one room with one outdoor and one indoor unit. Multi-zone connects 2-5 indoor units to one outdoor condenser for independent control in each room.

Common Mini Split Issues

If your mini split blows warm air, check the run capacitor, clean filters, and verify the outdoor unit isn't blocked. See our Fujitsu, Mitsubishi, Daikin, and LG error code guides.

Frequently Asked Questions

What size mini split for 500 sq ft?
A 500 sq ft room needs 12,000-18,000 BTU. In hot climates with full sun, go with 18K. In moderate climates with good insulation, 12K may suffice.
Can a mini split heat and cool?
Yes, most modern mini splits are heat pumps providing both heating and cooling efficiently down to about 5-15°F.
How many mini splits for my house?
Plan one indoor unit per room. A 1,500 sq ft home typically needs 3-4 units on a multi-zone system.

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