Calculation method
How we calculate the amount of rainwater you can collect – formulas, data sources and assumptions.
Location-based precipitation data
RainTact retrieves historical precipitation data from Open-Meteo for the location the user enters. The calculation is based on precipitation data over a longer historical period.
Our own calculation engine
RainTact's own backend calculator processes the precipitation data together with roof area, roof material and the other calculation parameters.
Roof material and runoff
Different roof materials have different runoff rates. RainTact therefore takes the selected roof material into account in the calculation.
Month-by-month analysis
The calculation is made month by month across the historical period and compiled into a clear monthly and annual result.
Historical basis
RainTact uses historical precipitation data over a longer period of time as the basis for the calculation.
Report results
The result is compiled into annual results, monthly results, charts, tables and comparisons in the rainwater report.