StormCAD results are different when compared to the results from InRoads Storm and Sanitary
Some difference in results may be expected, even when using the Rational Method to solve for a system. First, be sure to check the headloss method for structures in your model, such as manholes and catch basins. InRoads uses the HEC-22 2nd Edition headloss method, but StormCAD as a number of different headloss methods available. If the headloss method is different, the overall results may be different as well.
In addition, calculations in StormCAD can be based on either EGL or HGL, which can be toggled in the calculation options. Adjusting this in StormCAD may yield results that are similar in InRoads.
How does StormCAD integrate with InRoads, PowerCivil and GEOPAK?