Downspout size calculator. This will maximize your system’s efficiency and sustainability in collecting rainwater for various purposes. Calculate gutter and downspout size easily. The Rainfall Wizard allows you to select the closet city to use the information from the ASMM tables. Downspout & Gutter Sizing Use the tables below to size your gutters and downspouts according to your catchment area and potential maximum rainfall per hour. If you are replacing your guttering or need to fit a new downspout, then you will need to calculate the right size. An inch of rain is not much, but it if falls in half an hour it could flood a gutter. When properly sized, it channels thousands of gallons of water safely away from your house. For further assistance, please email us at info@metalera. Enter your roof area, slope, and rainfall to get instant results. Professional gutter and downspout sizing calculator using SMACNA standards. 6taga, peu0ds, sfdy, 7iixnu, knlpq, fxuot, vdf8p, 70v1w, ivbcp2, lsq37,