Is 3" large enough for a downspout? Should it be the same size as the gutter?

Is 3" large enough for a downspout? should it be the same size as the gutter?
Three inches should be good.

Downspouts are not the same size as the gutter. 3" is the norm for most buildings but you'd need to go larger if this where a barn or commercial building.

Is 3" large enough for a downspout? should it be the same size as the gutter?
Sorry about the earlier post don't know what I saw but the word "gutter"... lol

A 2" X 3" spout is normal in most areas,a 3" X 4" spout is used for high water areas and light commercial applications.

Is 3" large enough for a downspout? should it be the same size as the gutter?

Hal, I would recommend using nothing but 3x4 downspouts especially if you have a lot of trees around your home or building that you are installing gutters and D/S. They tend not to get plugged up at the downspout area as easily as smaller D/S. The company that I work for installs a lot of Gutters every yr. and we don't install any thing now but large D/S and Gutters.

Hope this helps

Is 3" large enough for a downspout? should it be the same size as the gutter?
In the northern climates a 2x3 Downspout can handle 600 square feet of roof drainage area. Down South they require 3x4 and use 6" Gutter and larger. California uses only 1x2 downspouts. So it is really about how roof is being drained. How much rain your location gets (ie what part of the country) If you tell me that I can help you with exact downspout requirements. Source National Rain Gutter Contractor Association. Nrgca.org

Depends on avg. rainfall for your location, size of roof area being drained, spacing between downspouts, and total number of downspouts. This website (http://northclad.com/gutter-sizing-calculator/) has a calculator that lets you put in the variables then see your options.