Quickly calculate a radiator's heat output at different water and air temperatures.

Select the radiator that fits, based on heat losses and water temperature. Don't undersize or oversize and ensure the best energy efficiency possible. 

Low water temperature (e.g. with heat pump as heat generator) can greatly increase energy efficiency and keep the cost down, but it still needs to provide enough heat to keep the room or the building warm. That's why larger radiators are needed in such cases. Find out exactly how large quickly using this app. Anywhere, anytime, fast and simple.

** Note: metric units only.

*** This app is totally free - no ads, no in-app purchases. No account needed, no log-ins, no user data needed nor collected. ***


A radiator's heat output is highly dependent on temperature of water entering and leaving the radiator. Nominal heat output of a radiator can be found in a catalogue or a technical brochure. The nominal heat output is valid only at the conditions specified in the catalogue. This application will calculate the heat output of the selected radiator at conditions specified by the user. This is useful for the selection of the right size of a radiator when designing a new heating system, as modern heating systems tend to use lower water temperatures than those specified in catalogues. The reason is simple: lower temperatures mean higher energy efficiency and lower cost. The application can also be used for calculating the cooling output of convectors and fan-coils at various conditions.

The application is available in English, French, German and Italian languages.

The application does not contain ads.