Room size → BTU, tonnage & unit type
Short answer
A 1,200 sq ft space needs roughly 24,000 BTU (2 tons) of cooling and about a 50,000 BTU furnace in a temperate, average-insulation home. Size up for hot climates, poor insulation, high ceilings, or lots of sun.
Cooling needed
24,000 BTU
Tonnage
2 ton
Furnace (heating)
50,000 BTU
Unit type
Single-zone mini-split
For cooling, 1,200 sq ft at roughly 20 BTU per square foot works out to about 24,000 BTU (2 ton) in a temperate, average-insulation home. For heating, a furnace is sized by climate zone — around 50,000 BTU in a temperate climate, and more in a cold one (50–60 BTU/sq-ft up north).
These are whole-space estimates. Poor insulation, high ceilings, lots of glass, or an extreme climate all raise both numbers — run your home through the calculator to adjust them.
Real, widely available units in the 12,000 – 24,000 BTU class. Independent picks — we're not affiliated with any manufacturer or retailer and earn nothing from these links. Always match the unit's BTU to the size above.
Best overall
12k / 18k / 24k BTU
Ductless mini-split · heat pump · Cools + heats · strong all-rounder
A consistent independent favorite — efficient inverter heat pump that both cools in summer and heats in winter, at a mid-market price.
Find on AmazonBest value
12k / 18k / 24k BTU
Ductless mini-split · DIY · Pre-charged quick-connect · warranty holds on self-install
The only mainstream line with true pre-charged quick-connect line sets, so a homeowner can install it without a vacuum pump — and keep the full warranty.
Find on AmazonBudget pick
12k / 18k / 24k BTU
Ductless mini-split · Lowest entry price in the class
The budget way into a ductless heat pump. Field-charging and a licensed install get you the longer warranty.
Find on AmazonMini-splits mount permanently and need a small wall penetration; DIY kits are homeowner-installable, others want an HVAC tech.
About 24,000 BTU (2 tons) of cooling for 1,200 sq ft in a temperate, average-insulation home — more in a hot climate or with poor insulation.
Roughly a 50,000 BTU furnace in a temperate climate. Cold climates need 50–60 BTU/sq-ft, so the same home can need a larger furnace further north.
2 tons (24,000 BTU), since one ton equals 12,000 BTU. Confirm with a Manual J load calculation before a professional install.