# Diameter of the rain gutter - how to choose correctly

Depending on the size of the roof and the shape of the gutter, the right size must be calculated so that the water is reliably kept away from the facade. There are a few basic rules to help you find the right diameter.

## Measure the size of the roof

The size of the roof can be used to find the right diameter for the rain gutter. If the roof size is just on the border between two sizes in the following list, you should definitely choose the next larger gutter.

• Also Read - 4 Important Measurements for the Rain Gutter
• Also Read - Every Rain Gutter Needs a Downpipe
• Also Read - What Diameter For The Downpipe?

If you install two downpipes and drain the water at both ends, for example, you only need to consider half the roof area in the calculation.

### Roof sizes for semicircular rain gutter

• Up to 25 square meters of roof area with a diameter of 70 millimeters
• Up to 50 square meters of roof area 100 millimeters in diameter
• Up to 100 square meters of roof area 125 millimeters in diameter
• Up to 160 square meters of roof area 150 millimeters in diameter

### Calculate the size of the box-shaped rain gutter

The ten centimeter wide box-shaped gutter is not available in every building materials store. Either you take the next larger rain gutter, or you use another drain. So all the water can be absorbed.

• Up to 25 square meters of roof area with a diameter of 70 millimeters
• Up to 50 square meters of roof area 85 millimeters in diameter
• up to 100 square meters of roof area 100 millimeters in diameter
• Up to 160 square meters roof area 120 millimeters in diameter

## Corresponding drop pipes for the rain channels

• Up to 25 square meters roof surface 60 mm diameter
• Up to 50 square meters roof surface 80 mm diameter
• Up to 100 square meters roof surface 100 mm diameter
• Up to 160 square meters roof surface 100/120 mm diameter
Tips & tricks As you can see, the larger roof surfaces require a smaller diameter in the gutter when a box-shaped gutter is used. Therefore, the box-shaped gutter can fit better in certain cases.

Wherever a huge semicircular gutter ruined the look, as with a low house with a large roof surface or a so-called single roof house, a box-shaped rain trench should be used.