9K BTU up to 450sq ft (typically a small office)

12K BTU for 450 - 550sq ft (typically a small family room)

15K BTU for 550 - 750sq ft (typically a standard garage)

18K BTU for 750 - 1,000sq ft (typically a basement)

24K BTU for 1,000 - 1,250sq ft (typically a large basement)

30K BTU for 1,250 - 1,500sq ft (typically an small pole barn)

36K BTU for 1,500 - 1,750sq ft (typically a sunroom, or large living room)

42K BTU for 1,750 - 2,000sq ft (typically a studio apartment)

48K BTU for 2,000 - 2,500sq ft (typically a large workshop)