Gutter Slope Calculator

How It Works

Gutters must slope toward downspouts to prevent standing water, which causes mosquito breeding, corrosion, and overflow. The standard slope is 1/2 inch of drop for every 10 feet of gutter run. For runs over 40 feet, consider placing the downspout at the center and sloping both halves toward it. Use a chalk line at the high point and measure down at the low point to set your slope. The gutter should sit about 1 inch below the roof edge. Too much slope makes the gutter visually obvious from the ground; too little causes pooling. In practice, snap a chalk line and hang hangers along it.