HVAC BTU Calculator
Find out exactly how many BTUs and AC Tons you need to perfectly heat or cool your room.
Understanding BTUs & Tonnage
BTU (British Thermal Unit) is a standard measure of energy. In HVAC, it measures how much heat an air conditioner can remove from a room per hour.
Tonnage doesn't mean how much the AC unit weighs! It refers to the cooling capacity. Long ago, people cooled buildings with blocks of ice. 1 "Ton" of AC capacity is equal to the amount of heat required to melt 1 ton of ice in 24 hours (which is exactly 12,000 BTUs).
Warning: Do not buy an oversized AC unit "just in case." An oversized unit will cool the room too fast and shut off before it has a chance to remove humidity from the air, leaving the room feeling cold but damp and clammy.