BTU Calculator Lite - AC play online

This application is a must for any plumber, builder or home DIY enthusiast, in fact anyone who wants to find out what radiator or AC BTU's are required for a particular room size.


Whether you have existing radiators (or Fan Coil Units - FCU) and want to check that they are the correct size or if you are adding a new radiator (FCU) to a room - this is the application for you.


BTU Calculator Features

Basic Calculations

Advanced Calculations

Electricity consumption and cost (monthly and annual) for your system

Location based climate data

AC or Heating Calculations for temperature increase/ decrease

Room volume

Room use

Double glazing plastic/ metal/ wooden frame windows

Single glazing metal/ wooden frame windows

Insulated/ uninsulated walls

Room position


The annual simulation of the required system will give you a detailed electricity consumption and cost during winter months.


Choose the right size of heat pump, AC or any other thermal source.


Do not undersize or oversize your system. Make an informed decision and choose the correct design/ power.


Design your new home or check your existing one, and be prepared before you receive any offer from the companies or plumbers.


The simple yet intuitive interface allows you the choice of measurements in feet or meters, Celsius or Fahrenheit degrees.


This calculator has the added benefit of showing you the BTU required and also the kW required.


Please note that some of the app features are available only in the premium version.


Thank you for using our app!