Cheapest 18,000 BTU mini split per BTU

$/1,000 BTU	Price	BTU/h	Zones	Efficiency	Volts	Line set	System
per 1,000 BTU/h$44.44Best single-zone	price$799.99	18,000	Single	19SEER2	208-230V	—	Electactic SE7203SP 18K Easy DIY All specs Volts 208-230V Line set —
per 1,000 BTU/h$50.00×1.13	price$899.99	18,000	Single	23SEER2	—	—	TURBRO 18,000 BTU Ductless Mini Split Invert · 3rd-party All specs Volts — Line set —
per 1,000 BTU/h$61.11Best two-zone	price$1,099.99	18,000	2-zone	20SEER2	208-230V	25 ft	HUMSURE 18000 BTU 2‑Zone Mini Split Air Conditioner · 3rd-party All specs Volts 208-230V Line set 25 ft
per 1,000 BTU/h$99.39×2.24	price$1,789.00	18,000	Single	23SEER2	230V	25 ft	Klimaire DIY 18K Quick Connect · 3rd-party All specs Volts 230V Line set 25 ft
per 1,000 BTU/h$155.56×3.50	price$2,799.99	18,000	Single	23.5SEER2	230V	—	Zone Air 18,000 BTU DIY Ductless Mini Split · 3rd-party All specs Volts 230V Line set —
per 1,000 BTU/h$161.61×3.64	price$2,909.00	18,000	Single	21SEER2	—	25 ft	MRCOOL DIY 18K 5th Gen All specs Volts — Line set 25 ft
per 1,000 BTU/h$205.55×3.36	price$3,699.99	18,000	2-zone	24SEER2	230V	—	Zone Air 2 Zone 18,000 BTU 9K+9K · 3rd-party All specs Volts 230V Line set —
per 1,000 BTU/h$206.56Best three-zone	price$3,718.00	18,000	3-zone	23.9SEER2	240V	25 ft	MRCOOL DIY Multi Zone 18K 3-Zone · 3rd-party All specs Volts 240V Line set 25 ft

×N is how many times the cheapest in-stock system of this size and class the row costs per BTU. The crowned row is the baseline.

At 18,000 BTU the single-zone and multi-zone catalogues start to overlap in price, and they are not the same purchase. An 18k single-zone puts all its capacity into one head; an 18k three-zone splits it across three rooms and cannot deliver full output to any of them at once. This page ranks them separately for that reason.

Power supply

18,000 BTU is effectively always 208-230V, so budget for a dedicated circuit unless one is already in place.

The rule of thumb is a starting point, not a load calculation

Square footage alone ignores ceiling height, insulation, window area and orientation, climate zone, and how many people are in the room. Twenty BTU per square foot is a sanity check, not an answer: a sunny top-floor room with single glazing can need half again as much as the same floor area in a shaded, well-insulated basement. Our sizing calculator applies the same rule of thumb with the adjustments spelled out, and a proper Manual J calculation beats both.

How this ranking is built

Every row is a system whose price was confirmed live on the last run. Anything flagged as an estimate, or whose listing failed verification, is excluded from this table entirely rather than shown with a caveat. The BEST mark goes to the lowest $/BTU that is actually in stock, within one install class and one zone count — where more than one class is present the badge names which one it won. See what counts as a good price per BTU.