A window air conditioner is a seasonal appliance you install in a sash, usually to cool one room, with a relatively low upfront cost. A ductless mini-split is a fixed split system with an outdoor unit and one or more indoor heads. Most mini-splits sold today are heat pumps, so they heat as well as cool. They are generally quieter and more efficient, and they require a proper electrical circuit, a refrigerant-rated install, and usually a permit.
Do not compare a SEER2 mini-split with a window unit’s older EER or CEER as if the numbers were the same scale without checking the test method. The right comparison for operating cost is seasonal electricity use at your rates, not a headline efficiency number.
Sizing is a separate trap: window-unit “BTU by square foot” charts and mini-split manufacturer rules of thumb (often 20–25 Btu/ft² as a starting point) are not ACCA Manual J. See the sizing question. This site does not pick brands and does not invent typical install prices here, because we do not have a tight, dated national pair of sources comparable to the Angi/Fixr panel ranges.
This is not a permit calculation, a utility approval, or a substitute for a licensed electrician, HVAC contractor, or the authority having jurisdiction. Panel Headroom is an independent educational site. It is not a utility, a certification body, or a contractor. Electrical and generator work that is done incorrectly can cause fire, shock, or carbon monoxide poisoning. Use the adopted electrical code and manufacturer instructions; pull permits where required.