Sizing Guide

These numbers are a starting point, not a load calculation. They get you to the right shelf; a tech with a Manual J load calculation gets you to the right unit.

Voltage first

Pick voltage before BTU. A mini split has to match the circuit you have or the one you will run.

• 115V units run on a dedicated 115V circuit. Most are 9k to 12k BTU. It is the simpler electrical job, but still usually a dedicated circuit, not a shared outlet. Check the spec sheet and local code.
• 208–230V units need a dedicated two-pole breaker and a disconnect at the condenser. Most 12k units and nearly all 18k and 24k units are 208–230V. They do not plug into a wall outlet.

If you do not know what circuit you can add, ask an electrician before you order. Then pick BTU by room.

BTU by room size

Measure the room: length times width in feet. If it opens into another space with no door, add that space.

Adjust up when

• Ceilings are over 8 ft.
• The room faces west or south with large windows.
• Insulation is poor, or the room sits over a garage or under a roof with no attic.
• It is a kitchen. Ovens and cooktops add heat.
• You are in Florida or on the Gulf Coast. Humidity is a load too, and a unit that runs longer pulls more of it out.
• Several people or a lot of equipment use the room at once.

If one of these applies, aim for the top of the range. If 2 or more apply, go up a size.

Do not oversize by habit

Bigger is not safer. An oversized unit cools the air fast and shuts off before it pulls the humidity out. The room feels cold and damp. Pick the size that fits the room and its loads, not the biggest one on the page.

When to call a tech

Call a tech before you buy if any of these apply:

• You want to condition a whole floor or several rooms with one system.
• The space is a converted garage, sunroom, or addition with unknown insulation.
• Heating matters as much as cooling. Heat output drops as the outdoor temperature drops, and HSPF2 alone will not tell you what a unit does at 5°F.
• You are not sure what circuit you have.

A Manual J load calculation takes the guesswork out. It is the right answer for a whole floor.

Reading the spec sheet

SEER2 is cooling efficiency. HSPF2 is heating efficiency. Higher is better, and both are on each product page. Rated BTU is measured at standard test conditions; real output moves with outdoor temperature and line set length.

To compare units, see all mini splits. For circuit and disconnect requirements, see the Installation page.