Gutter Flow Rate Calculator

Formula

To calculate the Gutter Flow Rate (\(FR\)):

\[ FR = \left(\frac{RI}{60}\right) \times \left(\frac{GA}{231}\right) \]

Where:

\(FR\) is the flow rate (gallons per minute)
\(RI\) is the rain intensity (inches per hour)
\(GA\) is the gutter area (square inches)

What is Gutter Flow Rate?

Gutter flow rate is the volume of water that can flow through a gutter system per unit of time, typically measured in gallons per minute (GPM). It is an important consideration in the design of gutter and downspout systems for buildings, as it affects the system’s ability to handle rainfall without overflowing. The flow rate is determined by the rain intensity and the cross-sectional area of the gutter.

Example Calculation 1

Let's assume the following values:

Rain Intensity (\(RI\)) = 2 inches per hour
Gutter Area (\(GA\)) = 100 square inches

Using the formula:

\[ FR = \left(\frac{2}{60}\right) \times \left(\frac{100}{231}\right) \approx 0.0145 \text{ gallons per minute} \]

The gutter flow rate is approximately 0.0145 gallons per minute.

Example Calculation 2

Let's assume the following values:

Rain Intensity (\(RI\)) = 3 inches per hour
Gutter Area (\(GA\)) = 150 square inches

Using the formula:

\[ FR = \left(\frac{3}{60}\right) \times \left(\frac{150}{231}\right) \approx 0.0325 \text{ gallons per minute} \]

The gutter flow rate is approximately 0.0325 gallons per minute.