BTU Calculator

Use it when your task matches one of these common needs: Estimate a window or room air conditioner size. Adjust for sunny or shaded rooms. It works best when you already know the measurements, amounts, units, or options the page asks for.

In plain language: The calculator starts with a room-size BTU table, adjusts for ceiling height, sunlight, extra people, and kitchen heat, then rounds to a practical BTU amount. The examples on the page are there so you can compare your inputs with a worked example before copying the answer.

Room square feet: the floor area of the room you want to cool. Ceiling height: the room height. Taller rooms have more air volume than a normal 8-foot room. Sunlight: whether the room is normally shaded, average, or sunny. Kitchen heat load: extra cooling demand from cooking appliances and kitchen heat.

Read the headline answer, then check the smaller lines beside it. For everyday tools, those lines usually show the distance, time, cost, units, or setting that made the answer change.

This is a room AC shopping estimate, not a full HVAC load calculation. Insulation, climate, windows, ducts, and humidity matter. Also check the unit, scale, mode, and result limit because small input changes can change the answer.

An oversized room air conditioner can cool the air quickly but cycle off before removing enough humidity. That can make the room feel cold and clammy instead of comfortable.

No. The calculator runs in your browser tab. Your recent answers stay only on the page while you use it, and they are not sent to a server.