★★★★★
Average rating on the App Store. Apple doesn't publish how many ratings each star has.
Where this app stands in Ireland, updated 17 Oct 2026
Top free
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Top paid · All apps and games
#77 –
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Improved performance and updated user interface
Heatloss helps plumbers, heating engineers, and installers estimate the heat output required for each room in a building. Calculate fabric and ventilation heat loss using room dimensions, component areas, U-values, internal temperatures, external temperatures, and air-change rates. Each room’s result is shown in both Watts and BTU, helping you choose a radiator with an appropriate heat output. The app keeps track of every room in the project and provides a running total for the whole building, giving a clear estimate of the overall heat output required from the heating system or boiler. Features • Calculate room-by-room heat loss • Include fabric and ventilation losses • Track multiple rooms in one building • View totals in Watts and BTU • Use room temperature and air-change reference data • Estimate the total heating output required for the property